docs: add v0.5.2 release notes

Add changelog entries for recent commits:
- Health package: Kubernetes health probes
- Logger package: runtime level control and fixes
- Database package: config file override support

CHANGELOG.md

@@ -0,0 +1,53 @@
+# Release Notes - v0.5.2
+
+## Health Package
+- **Kubernetes-native health probes** - Added dedicated handlers for liveness (`/healthz`), readiness (`/readyz`), and startup (`/startupz`) probes
+- **Flexible configuration options** - New `WithLivenessHandler`, `WithReadinessHandler`, `WithStartupHandler`, and `WithServiceName` options
+- **JSON response formats** - Structured probe responses with service identification
+- **Backward compatibility** - Maintains existing `/__health` and `/` endpoints
+
+## Logger Package
+- **Runtime log level control** - Independent level management for stderr and OTLP loggers via `SetLevel()` and `SetOTLPLevel()`
+- **Environment variable support** - Configure levels with `LOG_LEVEL` and `OTLP_LOG_LEVEL` env vars
+- **String parsing utility** - New `ParseLevel()` function for converting string levels to `slog.Level`
+- **Buffering exporter fix** - Resolved "unlock of unlocked mutex" panic in `bufferingExporter`
+- **Initialization redesign** - Eliminated race conditions in TLS/tracing setup retry logic
+
+## Database Package
+- **Configuration file override** - Added `DATABASE_CONFIG_FILE` environment variable to specify custom database configuration file paths
+- **Flexible path configuration** - Override default `["database.yaml", "/vault/secrets/database.yaml"]` search paths when needed
+
+# Release Notes - v0.5.1
+
+## Observability Enhancements
+
+### OTLP Metrics Support
+- **New `metrics/` package** - OpenTelemetry-native metrics with OTLP export support for structured metrics collection
+- **Centralized OTLP configuration** - Refactored configuration to `internal/tracerconfig/` to eliminate code duplication across tracing, logging, and metrics
+- **HTTP retry support** - Added consistent retry configuration for all HTTP OTLP exporters to improve reliability
+
+### Enhanced Logging
+- **Buffering exporter** - Added OTLP log buffering to queue logs until tracing configuration is available
+- **TLS support for logs** - Client certificate authentication support for secure OTLP log export
+- **Improved logfmt formatting** - Better structured output for log messages
+
+### Tracing Improvements
+- **HTTP retry support** - OTLP trace requests now automatically retry on failure when using HTTP transport
+
+## Build System
+
+### Version Package Enhancements
+- **Unix epoch build time support** - Build time can now be injected as Unix timestamps (`$(date +%s)`) in addition to RFC3339 format
+- **Simplified build commands** - Reduces complexity of ldflags injection while maintaining backward compatibility
+- **Consistent output format** - All build times normalize to RFC3339 format regardless of input
+
+## API Changes
+
+### New Public Interfaces
+- `metrics.NewMeterProvider()` - Create OTLP metrics provider with centralized configuration
+- `metrics.Shutdown()` - Graceful shutdown for metrics exporters
+- `internal/tracerconfig` - Shared OTLP configuration utilities (internal package)
+
+### Dependencies
+- Added explicit OpenTelemetry metrics dependencies to `go.mod`
+- Updated tracing dependencies for retry support

database/config.go

@@ -1,6 +1,7 @@
 package database
 
 import (
+	"os"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -36,10 +37,20 @@ type ConfigOptions struct {
 	ConnMaxLifetime time.Duration
 }
 
+// getConfigFiles returns the list of config files to search for database configuration.
+// If DATABASE_CONFIG_FILE environment variable is set, it returns that single file.
+// Otherwise, it returns the default paths.
+func getConfigFiles() []string {
+	if configFile := os.Getenv("DATABASE_CONFIG_FILE"); configFile != "" {
+		return []string{configFile}
+	}
+	return []string{"database.yaml", "/vault/secrets/database.yaml"}
+}
+
 // DefaultConfigOptions returns the standard configuration options used by API package
 func DefaultConfigOptions() ConfigOptions {
 	return ConfigOptions{
-		ConfigFiles:          []string{"database.yaml", "/vault/secrets/database.yaml"},
+		ConfigFiles:          getConfigFiles(),
 		EnablePoolMonitoring: true,
 		PrometheusRegisterer: prometheus.DefaultRegisterer,
 		MaxOpenConns:         25,
@@ -51,7 +62,7 @@ func DefaultConfigOptions() ConfigOptions {
 // MonitorConfigOptions returns configuration options optimized for Monitor package
 func MonitorConfigOptions() ConfigOptions {
 	return ConfigOptions{
-		ConfigFiles:          []string{"database.yaml", "/vault/secrets/database.yaml"},
+		ConfigFiles:          getConfigFiles(),
 		EnablePoolMonitoring: false, // Monitor doesn't need metrics
 		PrometheusRegisterer: nil,   // No Prometheus dependency
 		MaxOpenConns:         10,

go.mod

@@ -19,12 +19,18 @@ require (
 	go.opentelemetry.io/contrib/exporters/autoexport v0.58.0
 	go.opentelemetry.io/contrib/instrumentation/github.com/labstack/echo/otelecho v0.58.0
 	go.opentelemetry.io/otel v1.33.0
+	go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.9.0
+	go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp v0.9.0
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.33.0
+	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.33.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.33.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.33.0
 	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.33.0
 	go.opentelemetry.io/otel/log v0.9.0
+	go.opentelemetry.io/otel/metric v1.33.0
 	go.opentelemetry.io/otel/sdk v1.33.0
 	go.opentelemetry.io/otel/sdk/log v0.9.0
+	go.opentelemetry.io/otel/sdk/metric v1.33.0
 	go.opentelemetry.io/otel/trace v1.33.0
 	golang.org/x/mod v0.22.0
 	golang.org/x/net v0.33.0
@@ -59,16 +65,10 @@ require (
 	github.com/valyala/fasttemplate v1.2.2 // indirect
 	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
 	go.opentelemetry.io/contrib/bridges/prometheus v0.58.0 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc v0.9.0 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp v0.9.0 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.33.0 // indirect
-	go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp v1.33.0 // indirect
 	go.opentelemetry.io/otel/exporters/prometheus v0.55.0 // indirect
 	go.opentelemetry.io/otel/exporters/stdout/stdoutlog v0.9.0 // indirect
 	go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v1.33.0 // indirect
 	go.opentelemetry.io/otel/exporters/stdout/stdouttrace v1.33.0 // indirect
-	go.opentelemetry.io/otel/metric v1.33.0 // indirect
-	go.opentelemetry.io/otel/sdk/metric v1.33.0 // indirect
 	go.opentelemetry.io/proto/otlp v1.4.0 // indirect
 	golang.org/x/crypto v0.31.0 // indirect
 	golang.org/x/sys v0.28.0 // indirect

health/health_server.go

@@ -1,13 +1,71 @@
 // Package health provides a standalone HTTP server for health checks.
 //
-// This package implements a simple health check server that can be used
+// This package implements a flexible health check server that supports
-// to expose health status endpoints for monitoring and load balancing.
+// different handlers for Kubernetes probe types (liveness, readiness, startup).
-// It supports custom health check handlers and provides structured logging
+// It provides structured logging, graceful shutdown, and standard HTTP endpoints
-// with graceful shutdown capabilities.
+// for monitoring and load balancing.
+//
+// # Kubernetes Probe Types
+//
+// Liveness Probe: Detects when a container is "dead" and needs restarting.
+// Should be a lightweight check that verifies the process is still running
+// and not in an unrecoverable state.
+//
+// Readiness Probe: Determines when a container is ready to accept traffic.
+// Controls which Pods are used as backends for Services. Should verify
+// the application can handle requests properly.
+//
+// Startup Probe: Verifies when a container application has successfully started.
+// Delays liveness and readiness probes until startup succeeds. Useful for
+// slow-starting applications.
+//
+// # Usage Examples
+//
+// Basic usage with a single handler for all probes:
+//
+//	srv := health.NewServer(myHealthHandler)
+//	srv.Listen(ctx, 9091)
+//
+// Advanced usage with separate handlers for each probe type:
+//
+//	srv := health.NewServer(nil,
+//		health.WithLivenessHandler(func(w http.ResponseWriter, r *http.Request) {
+//			// Simple alive check
+//			w.WriteHeader(http.StatusOK)
+//		}),
+//		health.WithReadinessHandler(func(w http.ResponseWriter, r *http.Request) {
+//			// Check if ready to serve traffic
+//			if err := checkDatabase(); err != nil {
+//				w.WriteHeader(http.StatusServiceUnavailable)
+//				return
+//			}
+//			w.WriteHeader(http.StatusOK)
+//		}),
+//		health.WithStartupHandler(func(w http.ResponseWriter, r *http.Request) {
+//			// Check if startup is complete
+//			if !applicationReady() {
+//				w.WriteHeader(http.StatusServiceUnavailable)
+//				return
+//			}
+//			w.WriteHeader(http.StatusOK)
+//		}),
+//		health.WithServiceName("my-service"),
+//	)
+//	srv.Listen(ctx, 9091)
+//
+// # Standard Endpoints
+//
+// The server exposes these endpoints:
+//   - /healthz - liveness probe (or general health if no specific handler)
+//   - /readyz - readiness probe (or general health if no specific handler)
+//   - /startupz - startup probe (or general health if no specific handler)
+//   - /__health - general health endpoint (backward compatibility)
+//   - / - general health endpoint (root path)
 package health
 
 import (
 	"context"
+	"encoding/json"
 	"log/slog"
 	"net/http"
 	"strconv"
@@ -21,23 +79,74 @@ import (
 // It runs separately from the main application server to ensure health
 // checks remain available even if the main server is experiencing issues.
 //
-// The server includes built-in timeouts, graceful shutdown, and structured
+// The server supports separate handlers for different Kubernetes probe types
-// logging for monitoring and debugging health check behavior.
+// (liveness, readiness, startup) and includes built-in timeouts, graceful
+// shutdown, and structured logging.
 type Server struct {
-	log      *slog.Logger
+	log              *slog.Logger
-	healthFn http.HandlerFunc
+	livenessHandler  http.HandlerFunc
+	readinessHandler http.HandlerFunc
+	startupHandler   http.HandlerFunc
+	generalHandler   http.HandlerFunc // fallback for /__health and / paths
+	serviceName      string
 }
 
-// NewServer creates a new health check server with the specified health handler.
+// Option represents a configuration option for the health server.
-// If healthFn is nil, a default handler that returns HTTP 200 "ok" is used.
+type Option func(*Server)
-func NewServer(healthFn http.HandlerFunc) *Server {
+
+// WithLivenessHandler sets a specific handler for the /healthz endpoint.
+// Liveness probes determine if a container should be restarted.
+func WithLivenessHandler(handler http.HandlerFunc) Option {
+	return func(s *Server) {
+		s.livenessHandler = handler
+	}
+}
+
+// WithReadinessHandler sets a specific handler for the /readyz endpoint.
+// Readiness probes determine if a container can receive traffic.
+func WithReadinessHandler(handler http.HandlerFunc) Option {
+	return func(s *Server) {
+		s.readinessHandler = handler
+	}
+}
+
+// WithStartupHandler sets a specific handler for the /startupz endpoint.
+// Startup probes determine if a container has finished initializing.
+func WithStartupHandler(handler http.HandlerFunc) Option {
+	return func(s *Server) {
+		s.startupHandler = handler
+	}
+}
+
+// WithServiceName sets the service name for JSON responses and logging.
+func WithServiceName(serviceName string) Option {
+	return func(s *Server) {
+		s.serviceName = serviceName
+	}
+}
+
+
+// NewServer creates a new health check server with optional probe-specific handlers.
+//
+// If healthFn is provided, it will be used as a fallback for any probe endpoints
+// that don't have specific handlers configured. If healthFn is nil, a default
+// handler that returns HTTP 200 "ok" is used as the fallback.
+//
+// Use the With* option functions to configure specific handlers for different
+// probe types (liveness, readiness, startup).
+func NewServer(healthFn http.HandlerFunc, opts ...Option) *Server {
 	if healthFn == nil {
 		healthFn = basicHealth
 	}
 	srv := &Server{
-		log:      logger.Setup(),
+		log:            logger.Setup(),
-		healthFn: healthFn,
+		generalHandler: healthFn,
 	}
+
+	for _, opt := range opts {
+		opt(srv)
+	}
+
 	return srv
 }
 
@@ -47,13 +156,27 @@ func (srv *Server) SetLogger(log *slog.Logger) {
 }
 
 // Listen starts the health server on the specified port and blocks until ctx is cancelled.
-// The server exposes the health handler at "/__health" with graceful shutdown support.
+// The server exposes health check endpoints with graceful shutdown support.
+//
+// Standard endpoints exposed:
+//   - /healthz - liveness probe (uses livenessHandler or falls back to generalHandler)
+//   - /readyz - readiness probe (uses readinessHandler or falls back to generalHandler)
+//   - /startupz - startup probe (uses startupHandler or falls back to generalHandler)
+//   - /__health - general health endpoint (uses generalHandler)
+//   - / - root health endpoint (uses generalHandler)
 func (srv *Server) Listen(ctx context.Context, port int) error {
 	srv.log.Info("starting health listener", "port", port)
 
 	serveMux := http.NewServeMux()
 
-	serveMux.HandleFunc("/__health", srv.healthFn)
+	// Register probe-specific handlers
+	serveMux.HandleFunc("/healthz", srv.createProbeHandler("liveness"))
+	serveMux.HandleFunc("/readyz", srv.createProbeHandler("readiness"))
+	serveMux.HandleFunc("/startupz", srv.createProbeHandler("startup"))
+
+	// Register general health endpoints for backward compatibility
+	serveMux.HandleFunc("/__health", srv.createGeneralHandler())
+	serveMux.HandleFunc("/", srv.createGeneralHandler())
 
 	hsrv := &http.Server{
 		Addr:         ":" + strconv.Itoa(port),
@@ -89,6 +212,121 @@ func (srv *Server) Listen(ctx context.Context, port int) error {
 	return g.Wait()
 }
 
+// createProbeHandler creates a handler for a specific probe type that provides
+// appropriate JSON responses and falls back to the general handler if no specific
+// handler is configured.
+func (srv *Server) createProbeHandler(probeType string) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var handler http.HandlerFunc
+
+		// Select the appropriate handler
+		switch probeType {
+		case "liveness":
+			handler = srv.livenessHandler
+		case "readiness":
+			handler = srv.readinessHandler
+		case "startup":
+			handler = srv.startupHandler
+		}
+
+		// Fall back to general handler if no specific handler is configured
+		if handler == nil {
+			handler = srv.generalHandler
+		}
+
+		// Create a response recorder to capture the handler's status code
+		recorder := &statusRecorder{ResponseWriter: w, statusCode: 200}
+		handler(recorder, r)
+
+		// If the handler already wrote a response, we're done
+		if recorder.written {
+			return
+		}
+
+		// Otherwise, provide a standard JSON response based on the status code
+		w.Header().Set("Content-Type", "application/json")
+
+		if recorder.statusCode >= 400 {
+			// Handler indicated unhealthy
+			switch probeType {
+			case "liveness":
+				json.NewEncoder(w).Encode(map[string]string{"status": "unhealthy"})
+			case "readiness":
+				json.NewEncoder(w).Encode(map[string]bool{"ready": false})
+			case "startup":
+				json.NewEncoder(w).Encode(map[string]bool{"started": false})
+			}
+		} else {
+			// Handler indicated healthy
+			switch probeType {
+			case "liveness":
+				json.NewEncoder(w).Encode(map[string]string{"status": "alive"})
+			case "readiness":
+				json.NewEncoder(w).Encode(map[string]bool{"ready": true})
+			case "startup":
+				json.NewEncoder(w).Encode(map[string]bool{"started": true})
+			}
+		}
+	}
+}
+
+// createGeneralHandler creates a handler for general health endpoints that provides
+// comprehensive health information.
+func (srv *Server) createGeneralHandler() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		// Create a response recorder to capture the handler's status code
+		// Use a buffer to prevent the handler from writing to the actual response
+		recorder := &statusRecorder{ResponseWriter: &discardWriter{}, statusCode: 200}
+		srv.generalHandler(recorder, r)
+
+		// Always provide a comprehensive JSON response for general endpoints
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(recorder.statusCode)
+
+		response := map[string]interface{}{
+			"status": map[bool]string{true: "healthy", false: "unhealthy"}[recorder.statusCode < 400],
+		}
+
+		if srv.serviceName != "" {
+			response["service"] = srv.serviceName
+		}
+
+		json.NewEncoder(w).Encode(response)
+	}
+}
+
+// statusRecorder captures the response status code from handlers while allowing
+// them to write their own response content if needed.
+type statusRecorder struct {
+	http.ResponseWriter
+	statusCode int
+	written    bool
+}
+
+func (r *statusRecorder) WriteHeader(code int) {
+	r.statusCode = code
+	r.ResponseWriter.WriteHeader(code)
+}
+
+func (r *statusRecorder) Write(data []byte) (int, error) {
+	r.written = true
+	return r.ResponseWriter.Write(data)
+}
+
+// discardWriter implements http.ResponseWriter but discards all writes.
+// Used to capture status codes without writing response content.
+type discardWriter struct{}
+
+func (d *discardWriter) Header() http.Header {
+	return make(http.Header)
+}
+
+func (d *discardWriter) Write([]byte) (int, error) {
+	return 0, nil
+}
+
+func (d *discardWriter) WriteHeader(int) {}
+
 // HealthCheckListener runs a simple HTTP server on the specified port for health check probes.
 func HealthCheckListener(ctx context.Context, port int, log *slog.Logger) error {
 	srv := NewServer(nil)

health/health_test.go

@@ -1,13 +1,14 @@
 package health
 
 import (
+	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 )
 
-func TestHealthHandler(t *testing.T) {
+func TestBasicHealthHandler(t *testing.T) {
 	req := httptest.NewRequest(http.MethodGet, "/__health", nil)
 	w := httptest.NewRecorder()
 
@@ -24,3 +25,129 @@ func TestHealthHandler(t *testing.T) {
 		t.Errorf("expected ok got %q", string(data))
 	}
 }
+
+func TestProbeHandlers(t *testing.T) {
+	// Test with separate handlers for each probe type
+	srv := NewServer(nil,
+		WithLivenessHandler(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		}),
+		WithReadinessHandler(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		}),
+		WithStartupHandler(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		}),
+		WithServiceName("test-service"),
+	)
+
+	tests := []struct {
+		handler        http.HandlerFunc
+		expectedStatus int
+		expectedBody   string
+	}{
+		{srv.createProbeHandler("liveness"), 200, `{"status":"alive"}`},
+		{srv.createProbeHandler("readiness"), 200, `{"ready":true}`},
+		{srv.createProbeHandler("startup"), 200, `{"started":true}`},
+		{srv.createGeneralHandler(), 200, `{"service":"test-service","status":"healthy"}`},
+	}
+
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("test_%d", i), func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, "/", nil)
+			w := httptest.NewRecorder()
+
+			tt.handler(w, req)
+
+			if w.Code != tt.expectedStatus {
+				t.Errorf("expected status %d, got %d", tt.expectedStatus, w.Code)
+			}
+
+			body := w.Body.String()
+			if body != tt.expectedBody+"\n" { // json.Encoder adds newline
+				t.Errorf("expected body %q, got %q", tt.expectedBody, body)
+			}
+		})
+	}
+}
+
+func TestProbeHandlerFallback(t *testing.T) {
+	// Test fallback to general handler when no specific handler is configured
+	generalHandler := func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}
+
+	srv := NewServer(generalHandler, WithServiceName("test-service"))
+
+	tests := []struct {
+		handler        http.HandlerFunc
+		expectedStatus int
+		expectedBody   string
+	}{
+		{srv.createProbeHandler("liveness"), 200, `{"status":"alive"}`},
+		{srv.createProbeHandler("readiness"), 200, `{"ready":true}`},
+		{srv.createProbeHandler("startup"), 200, `{"started":true}`},
+	}
+
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("fallback_%d", i), func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, "/", nil)
+			w := httptest.NewRecorder()
+
+			tt.handler(w, req)
+
+			if w.Code != tt.expectedStatus {
+				t.Errorf("expected status %d, got %d", tt.expectedStatus, w.Code)
+			}
+
+			body := w.Body.String()
+			if body != tt.expectedBody+"\n" { // json.Encoder adds newline
+				t.Errorf("expected body %q, got %q", tt.expectedBody, body)
+			}
+		})
+	}
+}
+
+func TestUnhealthyProbeHandlers(t *testing.T) {
+	// Test with handlers that return unhealthy status
+	srv := NewServer(nil,
+		WithLivenessHandler(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusServiceUnavailable)
+		}),
+		WithReadinessHandler(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusServiceUnavailable)
+		}),
+		WithStartupHandler(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusServiceUnavailable)
+		}),
+		WithServiceName("test-service"),
+	)
+
+	tests := []struct {
+		handler        http.HandlerFunc
+		expectedStatus int
+		expectedBody   string
+	}{
+		{srv.createProbeHandler("liveness"), 503, `{"status":"unhealthy"}`},
+		{srv.createProbeHandler("readiness"), 503, `{"ready":false}`},
+		{srv.createProbeHandler("startup"), 503, `{"started":false}`},
+	}
+
+	for i, tt := range tests {
+		t.Run(fmt.Sprintf("unhealthy_%d", i), func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, "/", nil)
+			w := httptest.NewRecorder()
+
+			tt.handler(w, req)
+
+			if w.Code != tt.expectedStatus {
+				t.Errorf("expected status %d, got %d", tt.expectedStatus, w.Code)
+			}
+
+			body := w.Body.String()
+			if body != tt.expectedBody+"\n" { // json.Encoder adds newline
+				t.Errorf("expected body %q, got %q", tt.expectedBody, body)
+			}
+		})
+	}
+}

internal/tracerconfig/config.go

@@ -0,0 +1,378 @@
+// Package tracerconfig provides a bridge to eliminate circular dependencies between
+// the logger and tracing packages. It stores tracer configuration and provides
+// factory functions that can be used by the logger package without importing tracing.
+package tracerconfig
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"fmt"
+	"net/url"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp"
+	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
+	sdklog "go.opentelemetry.io/otel/sdk/log"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	"google.golang.org/grpc/credentials"
+)
+
+const (
+	otelExporterOTLPProtoEnvKey        = "OTEL_EXPORTER_OTLP_PROTOCOL"
+	otelExporterOTLPTracesProtoEnvKey  = "OTEL_EXPORTER_OTLP_TRACES_PROTOCOL"
+	otelExporterOTLPLogsProtoEnvKey    = "OTEL_EXPORTER_OTLP_LOGS_PROTOCOL"
+	otelExporterOTLPMetricsProtoEnvKey = "OTEL_EXPORTER_OTLP_METRICS_PROTOCOL"
+)
+
+var errInvalidOTLPProtocol = errors.New("invalid OTLP protocol - should be one of ['grpc', 'http/protobuf']")
+
+// newInvalidProtocolError creates a specific error message for invalid protocols
+func newInvalidProtocolError(protocol, signalType string) error {
+	return fmt.Errorf("invalid OTLP protocol '%s' for %s - should be one of ['grpc', 'http/protobuf', 'http/json']", protocol, signalType)
+}
+
+// Validate checks the configuration for common errors and inconsistencies
+func (c *Config) Validate() error {
+	var errs []error
+
+	// Check that both Endpoint and EndpointURL are not specified
+	if c.Endpoint != "" && c.EndpointURL != "" {
+		errs = append(errs, errors.New("cannot specify both Endpoint and EndpointURL - use one or the other"))
+	}
+
+	// Validate EndpointURL format if specified
+	if c.EndpointURL != "" {
+		if _, err := url.Parse(c.EndpointURL); err != nil {
+			errs = append(errs, fmt.Errorf("invalid EndpointURL format: %w", err))
+		}
+	}
+
+	// Validate Endpoint format if specified
+	if c.Endpoint != "" {
+		// Basic validation - should not contain protocol scheme
+		if strings.Contains(c.Endpoint, "://") {
+			errs = append(errs, errors.New("Endpoint should not include protocol scheme (use EndpointURL for full URLs)"))
+		}
+		// Should not be empty after trimming whitespace
+		if strings.TrimSpace(c.Endpoint) == "" {
+			errs = append(errs, errors.New("Endpoint cannot be empty or whitespace"))
+		}
+	}
+
+	// Validate TLS configuration consistency
+	if c.CertificateProvider != nil && c.RootCAs == nil {
+		// This is just a warning - client cert without custom CAs is valid
+		// but might indicate a configuration issue
+	}
+
+	// Validate service name if specified
+	if c.ServiceName != "" && strings.TrimSpace(c.ServiceName) == "" {
+		errs = append(errs, errors.New("ServiceName cannot be empty or whitespace"))
+	}
+
+	// Combine all errors
+	if len(errs) > 0 {
+		var errMsgs []string
+		for _, err := range errs {
+			errMsgs = append(errMsgs, err.Error())
+		}
+		return fmt.Errorf("configuration validation failed: %s", strings.Join(errMsgs, "; "))
+	}
+
+	return nil
+}
+
+// ValidateAndStore validates the configuration before storing it
+func ValidateAndStore(ctx context.Context, cfg *Config, logFactory LogExporterFactory, metricFactory MetricExporterFactory, traceFactory TraceExporterFactory) error {
+	if cfg != nil {
+		if err := cfg.Validate(); err != nil {
+			return err
+		}
+	}
+	Store(ctx, cfg, logFactory, metricFactory, traceFactory)
+	return nil
+}
+
+// GetClientCertificate defines a function type for providing client certificates for mutual TLS.
+// This is used when exporting telemetry data to secured OTLP endpoints that require
+// client certificate authentication.
+type GetClientCertificate func(*tls.CertificateRequestInfo) (*tls.Certificate, error)
+
+// Config provides configuration options for OpenTelemetry tracing setup.
+// It supplements standard OpenTelemetry environment variables with additional
+// NTP Pool-specific configuration including TLS settings for secure OTLP export.
+type Config struct {
+	ServiceName         string               // Service name for resource identification (overrides OTEL_SERVICE_NAME)
+	Environment         string               // Deployment environment (development, staging, production)
+	Endpoint            string               // OTLP endpoint hostname/port (e.g., "otlp.example.com:4317")
+	EndpointURL         string               // Complete OTLP endpoint URL (e.g., "https://otlp.example.com:4317/v1/traces")
+	CertificateProvider GetClientCertificate // Client certificate provider for mutual TLS
+	RootCAs             *x509.CertPool       // CA certificate pool for server verification
+}
+
+// LogExporterFactory creates an OTLP log exporter using the provided configuration.
+// This allows the logger package to create exporters without importing the tracing package.
+type LogExporterFactory func(context.Context, *Config) (sdklog.Exporter, error)
+
+// MetricExporterFactory creates an OTLP metric exporter using the provided configuration.
+// This allows the metrics package to create exporters without importing the tracing package.
+type MetricExporterFactory func(context.Context, *Config) (sdkmetric.Exporter, error)
+
+// TraceExporterFactory creates an OTLP trace exporter using the provided configuration.
+// This allows for consistent trace exporter creation across packages.
+type TraceExporterFactory func(context.Context, *Config) (sdktrace.SpanExporter, error)
+
+// Global state for sharing configuration between packages
+var (
+	globalConfig          *Config
+	globalContext         context.Context
+	logExporterFactory    LogExporterFactory
+	metricExporterFactory MetricExporterFactory
+	traceExporterFactory  TraceExporterFactory
+	configMu              sync.RWMutex
+)
+
+// Store saves the tracer configuration and exporter factories for use by other packages.
+// This should be called by the tracing package during initialization.
+func Store(ctx context.Context, cfg *Config, logFactory LogExporterFactory, metricFactory MetricExporterFactory, traceFactory TraceExporterFactory) {
+	configMu.Lock()
+	defer configMu.Unlock()
+	globalConfig = cfg
+	globalContext = ctx
+	logExporterFactory = logFactory
+	metricExporterFactory = metricFactory
+	traceExporterFactory = traceFactory
+}
+
+// GetLogExporter returns the stored configuration and log exporter factory.
+// Returns nil values if no configuration has been stored yet.
+func GetLogExporter() (*Config, context.Context, LogExporterFactory) {
+	configMu.RLock()
+	defer configMu.RUnlock()
+	return globalConfig, globalContext, logExporterFactory
+}
+
+// GetMetricExporter returns the stored configuration and metric exporter factory.
+// Returns nil values if no configuration has been stored yet.
+func GetMetricExporter() (*Config, context.Context, MetricExporterFactory) {
+	configMu.RLock()
+	defer configMu.RUnlock()
+	return globalConfig, globalContext, metricExporterFactory
+}
+
+// GetTraceExporter returns the stored configuration and trace exporter factory.
+// Returns nil values if no configuration has been stored yet.
+func GetTraceExporter() (*Config, context.Context, TraceExporterFactory) {
+	configMu.RLock()
+	defer configMu.RUnlock()
+	return globalConfig, globalContext, traceExporterFactory
+}
+
+// Get returns the stored tracer configuration, context, and log exporter factory.
+// This maintains backward compatibility for the logger package.
+// Returns nil values if no configuration has been stored yet.
+func Get() (*Config, context.Context, LogExporterFactory) {
+	return GetLogExporter()
+}
+
+// IsConfigured returns true if tracer configuration has been stored.
+func IsConfigured() bool {
+	configMu.RLock()
+	defer configMu.RUnlock()
+	return globalConfig != nil && globalContext != nil
+}
+
+// Clear removes the stored configuration. This is primarily useful for testing.
+func Clear() {
+	configMu.Lock()
+	defer configMu.Unlock()
+	globalConfig = nil
+	globalContext = nil
+	logExporterFactory = nil
+	metricExporterFactory = nil
+	traceExporterFactory = nil
+}
+
+// getTLSConfig creates a TLS configuration from the provided Config.
+func getTLSConfig(cfg *Config) *tls.Config {
+	if cfg.CertificateProvider == nil {
+		return nil
+	}
+	return &tls.Config{
+		GetClientCertificate: cfg.CertificateProvider,
+		RootCAs:              cfg.RootCAs,
+	}
+}
+
+// getProtocol determines the OTLP protocol to use for the given signal type.
+// It follows OpenTelemetry environment variable precedence.
+func getProtocol(signalSpecificEnv string) string {
+	proto := os.Getenv(signalSpecificEnv)
+	if proto == "" {
+		proto = os.Getenv(otelExporterOTLPProtoEnvKey)
+	}
+	// Fallback to default, http/protobuf.
+	if proto == "" {
+		proto = "http/protobuf"
+	}
+	return proto
+}
+
+// CreateOTLPLogExporter creates an OTLP log exporter using the provided configuration.
+func CreateOTLPLogExporter(ctx context.Context, cfg *Config) (sdklog.Exporter, error) {
+	tlsConfig := getTLSConfig(cfg)
+	proto := getProtocol(otelExporterOTLPLogsProtoEnvKey)
+
+	switch proto {
+	case "grpc":
+		opts := []otlploggrpc.Option{
+			otlploggrpc.WithCompressor("gzip"),
+		}
+		if tlsConfig != nil {
+			opts = append(opts, otlploggrpc.WithTLSCredentials(credentials.NewTLS(tlsConfig)))
+		}
+		if len(cfg.Endpoint) > 0 {
+			opts = append(opts, otlploggrpc.WithEndpoint(cfg.Endpoint))
+		}
+		if len(cfg.EndpointURL) > 0 {
+			opts = append(opts, otlploggrpc.WithEndpointURL(cfg.EndpointURL))
+		}
+
+		return otlploggrpc.New(ctx, opts...)
+	case "http/protobuf", "http/json":
+		opts := []otlploghttp.Option{
+			otlploghttp.WithCompression(otlploghttp.GzipCompression),
+		}
+		if tlsConfig != nil {
+			opts = append(opts, otlploghttp.WithTLSClientConfig(tlsConfig))
+		}
+		if len(cfg.Endpoint) > 0 {
+			opts = append(opts, otlploghttp.WithEndpoint(cfg.Endpoint))
+		}
+		if len(cfg.EndpointURL) > 0 {
+			opts = append(opts, otlploghttp.WithEndpointURL(cfg.EndpointURL))
+		}
+
+		opts = append(opts, otlploghttp.WithRetry(otlploghttp.RetryConfig{
+			Enabled:         true,
+			InitialInterval: 3 * time.Second,
+			MaxInterval:     60 * time.Second,
+			MaxElapsedTime:  5 * time.Minute,
+		}))
+
+		return otlploghttp.New(ctx, opts...)
+	default:
+		return nil, newInvalidProtocolError(proto, "logs")
+	}
+}
+
+// CreateOTLPMetricExporter creates an OTLP metric exporter using the provided configuration.
+func CreateOTLPMetricExporter(ctx context.Context, cfg *Config) (sdkmetric.Exporter, error) {
+	tlsConfig := getTLSConfig(cfg)
+	proto := getProtocol(otelExporterOTLPMetricsProtoEnvKey)
+
+	switch proto {
+	case "grpc":
+		opts := []otlpmetricgrpc.Option{
+			otlpmetricgrpc.WithCompressor("gzip"),
+		}
+		if tlsConfig != nil {
+			opts = append(opts, otlpmetricgrpc.WithTLSCredentials(credentials.NewTLS(tlsConfig)))
+		}
+		if len(cfg.Endpoint) > 0 {
+			opts = append(opts, otlpmetricgrpc.WithEndpoint(cfg.Endpoint))
+		}
+		if len(cfg.EndpointURL) > 0 {
+			opts = append(opts, otlpmetricgrpc.WithEndpointURL(cfg.EndpointURL))
+		}
+
+		return otlpmetricgrpc.New(ctx, opts...)
+	case "http/protobuf", "http/json":
+		opts := []otlpmetrichttp.Option{
+			otlpmetrichttp.WithCompression(otlpmetrichttp.GzipCompression),
+		}
+		if tlsConfig != nil {
+			opts = append(opts, otlpmetrichttp.WithTLSClientConfig(tlsConfig))
+		}
+		if len(cfg.Endpoint) > 0 {
+			opts = append(opts, otlpmetrichttp.WithEndpoint(cfg.Endpoint))
+		}
+		if len(cfg.EndpointURL) > 0 {
+			opts = append(opts, otlpmetrichttp.WithEndpointURL(cfg.EndpointURL))
+		}
+
+		opts = append(opts, otlpmetrichttp.WithRetry(otlpmetrichttp.RetryConfig{
+			Enabled:         true,
+			InitialInterval: 3 * time.Second,
+			MaxInterval:     60 * time.Second,
+			MaxElapsedTime:  5 * time.Minute,
+		}))
+
+		return otlpmetrichttp.New(ctx, opts...)
+	default:
+		return nil, newInvalidProtocolError(proto, "metrics")
+	}
+}
+
+// CreateOTLPTraceExporter creates an OTLP trace exporter using the provided configuration.
+func CreateOTLPTraceExporter(ctx context.Context, cfg *Config) (sdktrace.SpanExporter, error) {
+	tlsConfig := getTLSConfig(cfg)
+	proto := getProtocol(otelExporterOTLPTracesProtoEnvKey)
+
+	var client otlptrace.Client
+
+	switch proto {
+	case "grpc":
+		opts := []otlptracegrpc.Option{
+			otlptracegrpc.WithCompressor("gzip"),
+		}
+		if tlsConfig != nil {
+			opts = append(opts, otlptracegrpc.WithTLSCredentials(credentials.NewTLS(tlsConfig)))
+		}
+		if len(cfg.Endpoint) > 0 {
+			opts = append(opts, otlptracegrpc.WithEndpoint(cfg.Endpoint))
+		}
+		if len(cfg.EndpointURL) > 0 {
+			opts = append(opts, otlptracegrpc.WithEndpointURL(cfg.EndpointURL))
+		}
+
+		client = otlptracegrpc.NewClient(opts...)
+	case "http/protobuf", "http/json":
+		opts := []otlptracehttp.Option{
+			otlptracehttp.WithCompression(otlptracehttp.GzipCompression),
+		}
+		if tlsConfig != nil {
+			opts = append(opts, otlptracehttp.WithTLSClientConfig(tlsConfig))
+		}
+		if len(cfg.Endpoint) > 0 {
+			opts = append(opts, otlptracehttp.WithEndpoint(cfg.Endpoint))
+		}
+		if len(cfg.EndpointURL) > 0 {
+			opts = append(opts, otlptracehttp.WithEndpointURL(cfg.EndpointURL))
+		}
+
+		opts = append(opts, otlptracehttp.WithRetry(otlptracehttp.RetryConfig{
+			Enabled:         true,
+			InitialInterval: 3 * time.Second,
+			MaxInterval:     60 * time.Second,
+			MaxElapsedTime:  5 * time.Minute,
+		}))
+
+		client = otlptracehttp.NewClient(opts...)
+	default:
+		return nil, newInvalidProtocolError(proto, "traces")
+	}
+
+	return otlptrace.New(ctx, client)
+}

internal/tracerconfig/config_test.go

@@ -0,0 +1,474 @@
+package tracerconfig
+
+import (
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"os"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	sdklog "go.opentelemetry.io/otel/sdk/log"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+)
+
+func TestStore_And_Retrieve(t *testing.T) {
+	// Clear any existing configuration
+	Clear()
+
+	ctx := context.Background()
+	config := &Config{
+		ServiceName: "test-service",
+		Environment: "test",
+		Endpoint:    "localhost:4317",
+	}
+
+	// Create mock factories
+	logFactory := func(context.Context, *Config) (sdklog.Exporter, error) { return nil, nil }
+	metricFactory := func(context.Context, *Config) (sdkmetric.Exporter, error) { return nil, nil }
+	traceFactory := func(context.Context, *Config) (sdktrace.SpanExporter, error) { return nil, nil }
+
+	// Store configuration
+	Store(ctx, config, logFactory, metricFactory, traceFactory)
+
+	// Test IsConfigured
+	if !IsConfigured() {
+		t.Error("IsConfigured() should return true after Store()")
+	}
+
+	// Test GetLogExporter
+	cfg, ctx2, factory := GetLogExporter()
+	if cfg == nil || ctx2 == nil || factory == nil {
+		t.Error("GetLogExporter() should return non-nil values")
+	}
+	if cfg.ServiceName != "test-service" {
+		t.Errorf("Expected ServiceName 'test-service', got '%s'", cfg.ServiceName)
+	}
+
+	// Test GetMetricExporter
+	cfg, ctx3, metricFact := GetMetricExporter()
+	if cfg == nil || ctx3 == nil || metricFact == nil {
+		t.Error("GetMetricExporter() should return non-nil values")
+	}
+
+	// Test GetTraceExporter
+	cfg, ctx4, traceFact := GetTraceExporter()
+	if cfg == nil || ctx4 == nil || traceFact == nil {
+		t.Error("GetTraceExporter() should return non-nil values")
+	}
+
+	// Test backward compatibility Get()
+	cfg, ctx5, logFact := Get()
+	if cfg == nil || ctx5 == nil || logFact == nil {
+		t.Error("Get() should return non-nil values for backward compatibility")
+	}
+}
+
+func TestClear(t *testing.T) {
+	// Store some configuration first
+	ctx := context.Background()
+	config := &Config{ServiceName: "test"}
+	Store(ctx, config, nil, nil, nil)
+
+	if !IsConfigured() {
+		t.Error("Should be configured before Clear()")
+	}
+
+	// Clear configuration
+	Clear()
+
+	if IsConfigured() {
+		t.Error("Should not be configured after Clear()")
+	}
+
+	// All getters should return nil
+	cfg, ctx2, factory := GetLogExporter()
+	if cfg != nil || ctx2 != nil || factory != nil {
+		t.Error("GetLogExporter() should return nil values after Clear()")
+	}
+}
+
+func TestConcurrentAccess(t *testing.T) {
+	Clear()
+
+	ctx := context.Background()
+	config := &Config{ServiceName: "concurrent-test"}
+
+	var wg sync.WaitGroup
+	const numGoroutines = 10
+
+	// Test concurrent Store and Get operations
+	wg.Add(numGoroutines * 2)
+
+	// Concurrent Store operations
+	for i := 0; i < numGoroutines; i++ {
+		go func() {
+			defer wg.Done()
+			Store(ctx, config, nil, nil, nil)
+		}()
+	}
+
+	// Concurrent Get operations
+	for i := 0; i < numGoroutines; i++ {
+		go func() {
+			defer wg.Done()
+			IsConfigured()
+			GetLogExporter()
+			GetMetricExporter()
+			GetTraceExporter()
+		}()
+	}
+
+	wg.Wait()
+
+	// Should be configured after all operations
+	if !IsConfigured() {
+		t.Error("Should be configured after concurrent operations")
+	}
+}
+
+func TestGetTLSConfig(t *testing.T) {
+	tests := []struct {
+		name     string
+		config   *Config
+		expected bool // whether TLS config should be nil
+	}{
+		{
+			name:     "nil certificate provider",
+			config:   &Config{},
+			expected: true, // should be nil
+		},
+		{
+			name: "with certificate provider",
+			config: &Config{
+				CertificateProvider: func(*tls.CertificateRequestInfo) (*tls.Certificate, error) {
+					return &tls.Certificate{}, nil
+				},
+			},
+			expected: false, // should not be nil
+		},
+		{
+			name: "with certificate provider and RootCAs",
+			config: &Config{
+				CertificateProvider: func(*tls.CertificateRequestInfo) (*tls.Certificate, error) {
+					return &tls.Certificate{}, nil
+				},
+				RootCAs: x509.NewCertPool(),
+			},
+			expected: false, // should not be nil
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tlsConfig := getTLSConfig(tt.config)
+			if tt.expected && tlsConfig != nil {
+				t.Errorf("Expected nil TLS config, got %v", tlsConfig)
+			}
+			if !tt.expected && tlsConfig == nil {
+				t.Error("Expected non-nil TLS config, got nil")
+			}
+			if !tt.expected && tlsConfig != nil {
+				if tlsConfig.GetClientCertificate == nil {
+					t.Error("Expected GetClientCertificate to be set")
+				}
+				if tt.config.RootCAs != nil && tlsConfig.RootCAs != tt.config.RootCAs {
+					t.Error("Expected RootCAs to be set correctly")
+				}
+			}
+		})
+	}
+}
+
+func TestGetProtocol(t *testing.T) {
+	// Save original env vars
+	originalGeneral := os.Getenv(otelExporterOTLPProtoEnvKey)
+	originalLogs := os.Getenv(otelExporterOTLPLogsProtoEnvKey)
+
+	defer func() {
+		// Restore original env vars
+		if originalGeneral != "" {
+			os.Setenv(otelExporterOTLPProtoEnvKey, originalGeneral)
+		} else {
+			os.Unsetenv(otelExporterOTLPProtoEnvKey)
+		}
+		if originalLogs != "" {
+			os.Setenv(otelExporterOTLPLogsProtoEnvKey, originalLogs)
+		} else {
+			os.Unsetenv(otelExporterOTLPLogsProtoEnvKey)
+		}
+	}()
+
+	tests := []struct {
+		name           string
+		signalSpecific string
+		generalProto   string
+		specificProto  string
+		expectedResult string
+	}{
+		{
+			name:           "no env vars set - default",
+			signalSpecific: otelExporterOTLPLogsProtoEnvKey,
+			expectedResult: "http/protobuf",
+		},
+		{
+			name:           "general env var set",
+			signalSpecific: otelExporterOTLPLogsProtoEnvKey,
+			generalProto:   "grpc",
+			expectedResult: "grpc",
+		},
+		{
+			name:           "specific env var overrides general",
+			signalSpecific: otelExporterOTLPLogsProtoEnvKey,
+			generalProto:   "grpc",
+			specificProto:  "http/protobuf",
+			expectedResult: "http/protobuf",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Clear env vars
+			os.Unsetenv(otelExporterOTLPProtoEnvKey)
+			os.Unsetenv(otelExporterOTLPLogsProtoEnvKey)
+
+			// Set test env vars
+			if tt.generalProto != "" {
+				os.Setenv(otelExporterOTLPProtoEnvKey, tt.generalProto)
+			}
+			if tt.specificProto != "" {
+				os.Setenv(tt.signalSpecific, tt.specificProto)
+			}
+
+			result := getProtocol(tt.signalSpecific)
+			if result != tt.expectedResult {
+				t.Errorf("Expected protocol '%s', got '%s'", tt.expectedResult, result)
+			}
+		})
+	}
+}
+
+func TestCreateExporterErrors(t *testing.T) {
+	ctx := context.Background()
+	config := &Config{
+		ServiceName: "test-service",
+		Endpoint:    "invalid-endpoint",
+	}
+
+	// Test with invalid protocol for logs
+	os.Setenv(otelExporterOTLPLogsProtoEnvKey, "invalid-protocol")
+	defer os.Unsetenv(otelExporterOTLPLogsProtoEnvKey)
+
+	_, err := CreateOTLPLogExporter(ctx, config)
+	if err == nil {
+		t.Error("Expected error for invalid protocol")
+	}
+	// Check that it's a protocol error (the specific message will be different now)
+	if !strings.Contains(err.Error(), "invalid OTLP protocol") {
+		t.Errorf("Expected protocol error, got %v", err)
+	}
+
+	// Test with invalid protocol for metrics
+	os.Setenv(otelExporterOTLPMetricsProtoEnvKey, "invalid-protocol")
+	defer os.Unsetenv(otelExporterOTLPMetricsProtoEnvKey)
+
+	_, err = CreateOTLPMetricExporter(ctx, config)
+	if err == nil {
+		t.Error("Expected error for invalid protocol")
+	}
+	if !strings.Contains(err.Error(), "invalid OTLP protocol") {
+		t.Errorf("Expected protocol error, got %v", err)
+	}
+
+	// Test with invalid protocol for traces
+	os.Setenv(otelExporterOTLPTracesProtoEnvKey, "invalid-protocol")
+	defer os.Unsetenv(otelExporterOTLPTracesProtoEnvKey)
+
+	_, err = CreateOTLPTraceExporter(ctx, config)
+	if err == nil {
+		t.Error("Expected error for invalid protocol")
+	}
+	if !strings.Contains(err.Error(), "invalid OTLP protocol") {
+		t.Errorf("Expected protocol error, got %v", err)
+	}
+}
+
+func TestCreateExporterValidProtocols(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	config := &Config{
+		ServiceName: "test-service",
+		Endpoint:    "localhost:4317", // This will likely fail to connect, but should create exporter
+	}
+
+	protocols := []string{"grpc", "http/protobuf", "http/json"}
+
+	for _, proto := range protocols {
+		t.Run("logs_"+proto, func(t *testing.T) {
+			os.Setenv(otelExporterOTLPLogsProtoEnvKey, proto)
+			defer os.Unsetenv(otelExporterOTLPLogsProtoEnvKey)
+
+			exporter, err := CreateOTLPLogExporter(ctx, config)
+			if err != nil {
+				// Connection errors are expected since we're not running a real OTLP server
+				// but the exporter should be created successfully
+				t.Logf("Connection error expected: %v", err)
+			}
+			if exporter != nil {
+				exporter.Shutdown(ctx)
+			}
+		})
+
+		t.Run("metrics_"+proto, func(t *testing.T) {
+			os.Setenv(otelExporterOTLPMetricsProtoEnvKey, proto)
+			defer os.Unsetenv(otelExporterOTLPMetricsProtoEnvKey)
+
+			exporter, err := CreateOTLPMetricExporter(ctx, config)
+			if err != nil {
+				t.Logf("Connection error expected: %v", err)
+			}
+			if exporter != nil {
+				exporter.Shutdown(ctx)
+			}
+		})
+
+		t.Run("traces_"+proto, func(t *testing.T) {
+			os.Setenv(otelExporterOTLPTracesProtoEnvKey, proto)
+			defer os.Unsetenv(otelExporterOTLPTracesProtoEnvKey)
+
+			exporter, err := CreateOTLPTraceExporter(ctx, config)
+			if err != nil {
+				t.Logf("Connection error expected: %v", err)
+			}
+			if exporter != nil {
+				exporter.Shutdown(ctx)
+			}
+		})
+	}
+}
+
+func TestConfigValidation(t *testing.T) {
+	tests := []struct {
+		name      string
+		config    *Config
+		shouldErr bool
+	}{
+		{
+			name:      "valid empty config",
+			config:    &Config{},
+			shouldErr: false,
+		},
+		{
+			name: "valid config with endpoint",
+			config: &Config{
+				ServiceName: "test-service",
+				Endpoint:    "localhost:4317",
+			},
+			shouldErr: false,
+		},
+		{
+			name: "valid config with endpoint URL",
+			config: &Config{
+				ServiceName: "test-service",
+				EndpointURL: "https://otlp.example.com:4317/v1/traces",
+			},
+			shouldErr: false,
+		},
+		{
+			name: "invalid - both endpoint and endpoint URL",
+			config: &Config{
+				ServiceName: "test-service",
+				Endpoint:    "localhost:4317",
+				EndpointURL: "https://otlp.example.com:4317/v1/traces",
+			},
+			shouldErr: true,
+		},
+		{
+			name: "invalid - endpoint with protocol",
+			config: &Config{
+				ServiceName: "test-service",
+				Endpoint:    "https://localhost:4317",
+			},
+			shouldErr: true,
+		},
+		{
+			name: "invalid - empty endpoint",
+			config: &Config{
+				ServiceName: "test-service",
+				Endpoint:    "   ",
+			},
+			shouldErr: true,
+		},
+		{
+			name: "invalid - malformed endpoint URL",
+			config: &Config{
+				ServiceName: "test-service",
+				EndpointURL: "://invalid-url-missing-scheme",
+			},
+			shouldErr: true,
+		},
+		{
+			name: "invalid - empty service name",
+			config: &Config{
+				ServiceName: "   ",
+				Endpoint:    "localhost:4317",
+			},
+			shouldErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := tt.config.Validate()
+			if tt.shouldErr && err == nil {
+				t.Error("Expected validation error, got nil")
+			}
+			if !tt.shouldErr && err != nil {
+				t.Errorf("Expected no validation error, got: %v", err)
+			}
+		})
+	}
+}
+
+func TestValidateAndStore(t *testing.T) {
+	Clear()
+
+	ctx := context.Background()
+
+	// Test with valid config
+	validConfig := &Config{
+		ServiceName: "test-service",
+		Endpoint:    "localhost:4317",
+	}
+
+	err := ValidateAndStore(ctx, validConfig, nil, nil, nil)
+	if err != nil {
+		t.Errorf("ValidateAndStore with valid config should not error: %v", err)
+	}
+
+	if !IsConfigured() {
+		t.Error("Should be configured after ValidateAndStore")
+	}
+
+	Clear()
+
+	// Test with invalid config
+	invalidConfig := &Config{
+		ServiceName: "test-service",
+		Endpoint:    "localhost:4317",
+		EndpointURL: "https://example.com:4317", // both specified - invalid
+	}
+
+	err = ValidateAndStore(ctx, invalidConfig, nil, nil, nil)
+	if err == nil {
+		t.Error("ValidateAndStore with invalid config should return error")
+	}
+
+	if IsConfigured() {
+		t.Error("Should not be configured after failed ValidateAndStore")
+	}
+}

logger/buffering_exporter.go

@@ -0,0 +1,204 @@
+package logger
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"go.ntppool.org/common/internal/tracerconfig"
+	otellog "go.opentelemetry.io/otel/sdk/log"
+)
+
+// bufferingExporter wraps an OTLP exporter and buffers logs until tracing is configured
+type bufferingExporter struct {
+	mu sync.RWMutex
+
+	// Buffered records while waiting for tracing config
+	buffer      [][]otellog.Record
+	bufferSize  int
+	maxBuffSize int
+
+	// Real exporter (created when tracing is configured)
+	exporter otellog.Exporter
+
+	// Thread-safe initialization state (managed only by checkReadiness)
+	initErr error
+
+	// Background checker
+	stopChecker chan struct{}
+	checkerDone chan struct{}
+}
+
+// newBufferingExporter creates a new exporter that buffers logs until tracing is configured
+func newBufferingExporter() *bufferingExporter {
+	e := &bufferingExporter{
+		maxBuffSize: 1000, // Max number of batches to buffer
+		stopChecker: make(chan struct{}),
+		checkerDone: make(chan struct{}),
+	}
+
+	// Start background readiness checker
+	go e.checkReadiness()
+
+	return e
+}
+
+// Export implements otellog.Exporter
+func (e *bufferingExporter) Export(ctx context.Context, records []otellog.Record) error {
+	// Check if exporter is ready (initialization handled by checkReadiness goroutine)
+	e.mu.RLock()
+	exporter := e.exporter
+	e.mu.RUnlock()
+
+	if exporter != nil {
+		return exporter.Export(ctx, records)
+	}
+
+	// Not ready yet, buffer the records
+	return e.bufferRecords(records)
+}
+
+// initialize attempts to create the real OTLP exporter using tracing config
+func (e *bufferingExporter) initialize() error {
+	cfg, ctx, factory := tracerconfig.Get()
+	if cfg == nil || ctx == nil || factory == nil {
+		return errors.New("tracer not configured yet")
+	}
+
+	// Add timeout for initialization
+	initCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	defer cancel()
+
+	exporter, err := factory(initCtx, cfg)
+	if err != nil {
+		return fmt.Errorf("failed to create OTLP exporter: %w", err)
+	}
+
+	e.mu.Lock()
+	e.exporter = exporter
+	flushErr := e.flushBuffer(initCtx)
+	e.mu.Unlock()
+
+	if flushErr != nil {
+		// Log but don't fail initialization
+		Setup().Warn("buffer flush failed during initialization", "error", flushErr)
+	}
+
+	return nil
+}
+
+// bufferRecords adds records to the buffer for later processing
+func (e *bufferingExporter) bufferRecords(records []otellog.Record) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	// Buffer the batch if we have space
+	if e.bufferSize < e.maxBuffSize {
+		// Clone records to avoid retention issues
+		cloned := make([]otellog.Record, len(records))
+		for i, r := range records {
+			cloned[i] = r.Clone()
+		}
+		e.buffer = append(e.buffer, cloned)
+		e.bufferSize++
+	}
+
+	// Always return success to BatchProcessor
+	return nil
+}
+
+// checkReadiness periodically attempts initialization until successful
+func (e *bufferingExporter) checkReadiness() {
+	defer close(e.checkerDone)
+
+	ticker := time.NewTicker(1 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			// Check if we already have a working exporter
+			e.mu.RLock()
+			hasExporter := e.exporter != nil
+			e.mu.RUnlock()
+
+			if hasExporter {
+				return // Exporter ready, checker no longer needed
+			}
+
+			// Try to initialize
+			err := e.initialize()
+			e.mu.Lock()
+			e.initErr = err
+			e.mu.Unlock()
+
+		case <-e.stopChecker:
+			return
+		}
+	}
+}
+
+// flushBuffer sends all buffered batches through the real exporter
+func (e *bufferingExporter) flushBuffer(ctx context.Context) error {
+	if len(e.buffer) == 0 {
+		return nil
+	}
+
+	flushCtx, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+
+	var lastErr error
+	for _, batch := range e.buffer {
+		if err := e.exporter.Export(flushCtx, batch); err != nil {
+			lastErr = err
+		}
+	}
+
+	// Clear buffer after flush attempt
+	e.buffer = nil
+	e.bufferSize = 0
+
+	return lastErr
+}
+
+// ForceFlush implements otellog.Exporter
+func (e *bufferingExporter) ForceFlush(ctx context.Context) error {
+	e.mu.RLock()
+	defer e.mu.RUnlock()
+
+	if e.exporter != nil {
+		return e.exporter.ForceFlush(ctx)
+	}
+	return nil
+}
+
+// Shutdown implements otellog.Exporter
+func (e *bufferingExporter) Shutdown(ctx context.Context) error {
+	// Stop the readiness checker from continuing
+	close(e.stopChecker)
+
+	// Wait for readiness checker goroutine to complete
+	<-e.checkerDone
+
+	// Give one final chance for TLS/tracing to become ready for buffer flushing
+	e.mu.RLock()
+	hasExporter := e.exporter != nil
+	e.mu.RUnlock()
+
+	if !hasExporter {
+		err := e.initialize()
+		e.mu.Lock()
+		e.initErr = err
+		e.mu.Unlock()
+	}
+
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	if e.exporter != nil {
+		return e.exporter.Shutdown(ctx)
+	}
+	return nil
+}

logger/level_test.go

@@ -0,0 +1,235 @@
+package logger
+
+import (
+	"context"
+	"log/slog"
+	"os"
+	"testing"
+	"time"
+)
+
+func TestParseLevel(t *testing.T) {
+	tests := []struct {
+		name        string
+		input       string
+		expected    slog.Level
+		expectError bool
+	}{
+		{"empty string", "", slog.LevelInfo, false},
+		{"DEBUG upper", "DEBUG", slog.LevelDebug, false},
+		{"debug lower", "debug", slog.LevelDebug, false},
+		{"INFO upper", "INFO", slog.LevelInfo, false},
+		{"info lower", "info", slog.LevelInfo, false},
+		{"WARN upper", "WARN", slog.LevelWarn, false},
+		{"warn lower", "warn", slog.LevelWarn, false},
+		{"ERROR upper", "ERROR", slog.LevelError, false},
+		{"error lower", "error", slog.LevelError, false},
+		{"invalid level", "invalid", slog.LevelInfo, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			level, err := ParseLevel(tt.input)
+			if tt.expectError {
+				if err == nil {
+					t.Errorf("expected error for input %q, got nil", tt.input)
+				}
+			} else {
+				if err != nil {
+					t.Errorf("unexpected error for input %q: %v", tt.input, err)
+				}
+				if level != tt.expected {
+					t.Errorf("expected level %v for input %q, got %v", tt.expected, tt.input, level)
+				}
+			}
+		})
+	}
+}
+
+func TestSetLevel(t *testing.T) {
+	// Store original level to restore later
+	originalLevel := Level.Level()
+	defer Level.Set(originalLevel)
+
+	SetLevel(slog.LevelDebug)
+	if Level.Level() != slog.LevelDebug {
+		t.Errorf("expected Level to be Debug, got %v", Level.Level())
+	}
+
+	SetLevel(slog.LevelError)
+	if Level.Level() != slog.LevelError {
+		t.Errorf("expected Level to be Error, got %v", Level.Level())
+	}
+}
+
+func TestSetOTLPLevel(t *testing.T) {
+	// Store original level to restore later
+	originalLevel := OTLPLevel.Level()
+	defer OTLPLevel.Set(originalLevel)
+
+	SetOTLPLevel(slog.LevelWarn)
+	if OTLPLevel.Level() != slog.LevelWarn {
+		t.Errorf("expected OTLPLevel to be Warn, got %v", OTLPLevel.Level())
+	}
+
+	SetOTLPLevel(slog.LevelDebug)
+	if OTLPLevel.Level() != slog.LevelDebug {
+		t.Errorf("expected OTLPLevel to be Debug, got %v", OTLPLevel.Level())
+	}
+}
+
+func TestOTLPLevelHandler(t *testing.T) {
+	// Create a mock handler that counts calls
+	callCount := 0
+	mockHandler := &mockHandler{
+		handleFunc: func(ctx context.Context, r slog.Record) error {
+			callCount++
+			return nil
+		},
+	}
+
+	// Set OTLP level to Warn
+	originalLevel := OTLPLevel.Level()
+	defer OTLPLevel.Set(originalLevel)
+	OTLPLevel.Set(slog.LevelWarn)
+
+	// Create OTLP level handler
+	handler := newOTLPLevelHandler(mockHandler)
+
+	ctx := context.Background()
+
+	// Test that Debug and Info are filtered out
+	if handler.Enabled(ctx, slog.LevelDebug) {
+		t.Error("Debug level should be disabled when OTLP level is Warn")
+	}
+	if handler.Enabled(ctx, slog.LevelInfo) {
+		t.Error("Info level should be disabled when OTLP level is Warn")
+	}
+
+	// Test that Warn and Error are enabled
+	if !handler.Enabled(ctx, slog.LevelWarn) {
+		t.Error("Warn level should be enabled when OTLP level is Warn")
+	}
+	if !handler.Enabled(ctx, slog.LevelError) {
+		t.Error("Error level should be enabled when OTLP level is Warn")
+	}
+
+	// Test that Handle respects level filtering
+	now := time.Now()
+	debugRecord := slog.NewRecord(now, slog.LevelDebug, "debug message", 0)
+	warnRecord := slog.NewRecord(now, slog.LevelWarn, "warn message", 0)
+
+	handler.Handle(ctx, debugRecord)
+	if callCount != 0 {
+		t.Error("Debug record should not be passed to underlying handler")
+	}
+
+	handler.Handle(ctx, warnRecord)
+	if callCount != 1 {
+		t.Error("Warn record should be passed to underlying handler")
+	}
+}
+
+func TestEnvironmentVariables(t *testing.T) {
+	tests := []struct {
+		name         string
+		envVar       string
+		envValue     string
+		configPrefix string
+		testFunc     func(t *testing.T)
+	}{
+		{
+			name:     "LOG_LEVEL sets stderr level",
+			envVar:   "LOG_LEVEL",
+			envValue: "ERROR",
+			testFunc: func(t *testing.T) {
+				// Reset the setup state
+				resetLoggerSetup()
+
+				// Call setupStdErrHandler which should read the env var
+				handler := setupStdErrHandler()
+				if handler == nil {
+					t.Fatal("setupStdErrHandler returned nil")
+				}
+
+				if Level.Level() != slog.LevelError {
+					t.Errorf("expected Level to be Error after setting LOG_LEVEL=ERROR, got %v", Level.Level())
+				}
+			},
+		},
+		{
+			name:         "Prefixed LOG_LEVEL",
+			envVar:       "TEST_LOG_LEVEL",
+			envValue:     "DEBUG",
+			configPrefix: "TEST",
+			testFunc: func(t *testing.T) {
+				ConfigPrefix = "TEST"
+				defer func() { ConfigPrefix = "" }()
+
+				resetLoggerSetup()
+				handler := setupStdErrHandler()
+				if handler == nil {
+					t.Fatal("setupStdErrHandler returned nil")
+				}
+
+				if Level.Level() != slog.LevelDebug {
+					t.Errorf("expected Level to be Debug after setting TEST_LOG_LEVEL=DEBUG, got %v", Level.Level())
+				}
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Store original env value and level
+			originalEnv := os.Getenv(tt.envVar)
+			originalLevel := Level.Level()
+			defer func() {
+				os.Setenv(tt.envVar, originalEnv)
+				Level.Set(originalLevel)
+			}()
+
+			// Set test environment variable
+			os.Setenv(tt.envVar, tt.envValue)
+
+			// Run the test
+			tt.testFunc(t)
+		})
+	}
+}
+
+// mockHandler is a simple mock implementation of slog.Handler for testing
+type mockHandler struct {
+	handleFunc func(ctx context.Context, r slog.Record) error
+}
+
+func (m *mockHandler) Enabled(ctx context.Context, level slog.Level) bool {
+	return true
+}
+
+func (m *mockHandler) Handle(ctx context.Context, r slog.Record) error {
+	if m.handleFunc != nil {
+		return m.handleFunc(ctx, r)
+	}
+	return nil
+}
+
+func (m *mockHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return m
+}
+
+func (m *mockHandler) WithGroup(name string) slog.Handler {
+	return m
+}
+
+// resetLoggerSetup resets the sync.Once instances for testing
+func resetLoggerSetup() {
+	// Reset package-level variables
+	textLogger = nil
+	otlpLogger = nil
+	multiLogger = nil
+
+	// Note: We can't easily reset sync.Once instances in tests,
+	// but for the specific test we're doing (environment variable parsing)
+	// we can test the setupStdErrHandler function directly
+}

logger/logfmt.go

@@ -16,23 +16,28 @@ type logfmt struct {
 	mu   sync.Mutex
 }
 
+// createTextHandlerOptions creates the common slog.HandlerOptions used by all logfmt handlers
+func createTextHandlerOptions() *slog.HandlerOptions {
+	return &slog.HandlerOptions{
+		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+			if a.Key == slog.TimeKey && len(groups) == 0 {
+				return slog.Attr{}
+			}
+			if a.Key == slog.LevelKey && len(groups) == 0 {
+				return slog.Attr{}
+			}
+			return a
+		},
+	}
+}
+
 func newLogFmtHandler(next slog.Handler) slog.Handler {
 	buf := bytes.NewBuffer([]byte{})
 
 	h := &logfmt{
 		buf:  buf,
 		next: next,
-		txt: slog.NewTextHandler(buf, &slog.HandlerOptions{
+		txt:  slog.NewTextHandler(buf, createTextHandlerOptions()),
-			ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
-				if a.Key == slog.TimeKey && len(groups) == 0 {
-					return slog.Attr{}
-				}
-				if a.Key == slog.LevelKey && len(groups) == 0 {
-					return slog.Attr{}
-				}
-				return a
-			},
-		}),
 	}
 
 	return h
@@ -43,10 +48,11 @@ func (h *logfmt) Enabled(ctx context.Context, lvl slog.Level) bool {
 }
 
 func (h *logfmt) WithAttrs(attrs []slog.Attr) slog.Handler {
+	buf := bytes.NewBuffer([]byte{})
 	return &logfmt{
-		buf:  bytes.NewBuffer([]byte{}),
+		buf:  buf,
 		next: h.next.WithAttrs(slices.Clone(attrs)),
-		txt:  h.txt.WithAttrs(slices.Clone(attrs)),
+		txt:  slog.NewTextHandler(buf, createTextHandlerOptions()).WithAttrs(slices.Clone(attrs)),
 	}
 }
 
@@ -54,10 +60,11 @@ func (h *logfmt) WithGroup(g string) slog.Handler {
 	if g == "" {
 		return h
 	}
+	buf := bytes.NewBuffer([]byte{})
 	return &logfmt{
-		buf:  bytes.NewBuffer([]byte{}),
+		buf:  buf,
 		next: h.next.WithGroup(g),
-		txt:  h.txt.WithGroup(g),
+		txt:  slog.NewTextHandler(buf, createTextHandlerOptions()).WithGroup(g),
 	}
 }
 
@@ -69,10 +76,22 @@ func (h *logfmt) Handle(ctx context.Context, r slog.Record) error {
 		panic("buffer wasn't empty")
 	}
 
-	h.txt.Handle(ctx, r)
+	// Format using text handler to get the formatted message
-	r.Message = h.buf.String()
+	err := h.txt.Handle(ctx, r)
-	r.Message = strings.TrimSuffix(r.Message, "\n")
+	if err != nil {
+		return err
+	}
+
+	formattedMessage := h.buf.String()
+	formattedMessage = strings.TrimSuffix(formattedMessage, "\n")
 	h.buf.Reset()
 
-	return h.next.Handle(ctx, r)
+	// Create a new record with the formatted message
+	newRecord := slog.NewRecord(r.Time, r.Level, formattedMessage, r.PC)
+	r.Attrs(func(a slog.Attr) bool {
+		newRecord.AddAttrs(a)
+		return true
+	})
+
+	return h.next.Handle(ctx, newRecord)
 }

logger/logger.go

@@ -18,21 +18,27 @@
 //   - Context propagation for request-scoped logging
 //
 // Environment variables:
-//   - DEBUG: Enable debug level logging (configurable prefix via ConfigPrefix)
+//   - LOG_LEVEL: Set stderr log level (DEBUG, INFO, WARN, ERROR) (configurable prefix via ConfigPrefix)
+//   - OTLP_LOG_LEVEL: Set OTLP log level independently (configurable prefix via ConfigPrefix)
+//   - DEBUG: Enable debug level logging for backward compatibility (configurable prefix via ConfigPrefix)
 //   - INVOCATION_ID: Systemd detection for timestamp handling
 package logger
 
 import (
 	"context"
+	"fmt"
 	"log"
 	"log/slog"
 	"os"
 	"strconv"
 	"sync"
+	"time"
 
 	slogtraceid "github.com/remychantenay/slog-otel"
 	slogmulti "github.com/samber/slog-multi"
 	"go.opentelemetry.io/contrib/bridges/otelslog"
+	"go.opentelemetry.io/otel/log/global"
+	otellog "go.opentelemetry.io/otel/sdk/log"
 )
 
 // ConfigPrefix allows customizing the environment variable prefix for configuration.
@@ -40,6 +46,16 @@ import (
 // This enables multiple services to have independent logging configuration.
 var ConfigPrefix = ""
 
+var (
+	// Level controls the log level for the default stderr logger.
+	// Can be changed at runtime to adjust logging verbosity.
+	Level = new(slog.LevelVar) // Info by default
+
+	// OTLPLevel controls the log level for OTLP output.
+	// Can be changed independently from the stderr logger level.
+	OTLPLevel = new(slog.LevelVar) // Info by default
+)
+
 var (
 	textLogger  *slog.Logger
 	otlpLogger  *slog.Logger
@@ -53,21 +69,64 @@ var (
 	mu         sync.Mutex
 )
 
-func setupStdErrHandler() slog.Handler {
+// SetLevel sets the log level for the default stderr logger.
-	programLevel := new(slog.LevelVar) // Info by default
+// This affects the primary application logger returned by Setup().
+func SetLevel(level slog.Level) {
+	Level.Set(level)
+}
 
-	envVar := "DEBUG"
+// SetOTLPLevel sets the log level for OTLP output.
+// This affects the logger returned by SetupOLTP() and the OTLP portion of SetupMultiLogger().
+func SetOTLPLevel(level slog.Level) {
+	OTLPLevel.Set(level)
+}
+
+// ParseLevel converts a string log level to slog.Level.
+// Supported levels: "DEBUG", "INFO", "WARN", "ERROR" (case insensitive).
+// Returns an error for unrecognized level strings.
+func ParseLevel(level string) (slog.Level, error) {
+	switch {
+	case level == "":
+		return slog.LevelInfo, nil
+	case level == "DEBUG" || level == "debug":
+		return slog.LevelDebug, nil
+	case level == "INFO" || level == "info":
+		return slog.LevelInfo, nil
+	case level == "WARN" || level == "warn":
+		return slog.LevelWarn, nil
+	case level == "ERROR" || level == "error":
+		return slog.LevelError, nil
+	default:
+		return slog.LevelInfo, fmt.Errorf("unknown log level: %s", level)
+	}
+}
+
+func setupStdErrHandler() slog.Handler {
+	// Parse LOG_LEVEL environment variable
+	logLevelVar := "LOG_LEVEL"
 	if len(ConfigPrefix) > 0 {
-		envVar = ConfigPrefix + "_" + envVar
+		logLevelVar = ConfigPrefix + "_" + logLevelVar
 	}
 
-	if opt := os.Getenv(envVar); len(opt) > 0 {
+	if levelStr := os.Getenv(logLevelVar); levelStr != "" {
-		if debug, _ := strconv.ParseBool(opt); debug {
+		if level, err := ParseLevel(levelStr); err == nil {
-			programLevel.Set(slog.LevelDebug)
+			Level.Set(level)
 		}
 	}
 
-	logOptions := &slog.HandlerOptions{Level: programLevel}
+	// Maintain backward compatibility with DEBUG environment variable
+	debugVar := "DEBUG"
+	if len(ConfigPrefix) > 0 {
+		debugVar = ConfigPrefix + "_" + debugVar
+	}
+
+	if opt := os.Getenv(debugVar); len(opt) > 0 {
+		if debug, _ := strconv.ParseBool(opt); debug {
+			Level.Set(slog.LevelDebug)
+		}
+	}
+
+	logOptions := &slog.HandlerOptions{Level: Level}
 
 	if len(os.Getenv("INVOCATION_ID")) > 0 {
 		// don't add timestamps when running under systemd
@@ -85,9 +144,41 @@ func setupStdErrHandler() slog.Handler {
 
 func setupOtlpLogger() *slog.Logger {
 	setupOtlp.Do(func() {
-		otlpLogger = slog.New(
+		// Parse OTLP_LOG_LEVEL environment variable
-			newLogFmtHandler(otelslog.NewHandler("common")),
+		otlpLevelVar := "OTLP_LOG_LEVEL"
+		if len(ConfigPrefix) > 0 {
+			otlpLevelVar = ConfigPrefix + "_" + otlpLevelVar
+		}
+
+		if levelStr := os.Getenv(otlpLevelVar); levelStr != "" {
+			if level, err := ParseLevel(levelStr); err == nil {
+				OTLPLevel.Set(level)
+			}
+		}
+
+		// Create our buffering exporter
+		// It will buffer until tracing is configured
+		bufferingExp := newBufferingExporter()
+
+		// Use BatchProcessor with our custom exporter
+		processor := otellog.NewBatchProcessor(bufferingExp,
+			otellog.WithExportInterval(10*time.Second),
+			otellog.WithMaxQueueSize(2048),
+			otellog.WithExportMaxBatchSize(512),
 		)
+
+		// Create logger provider
+		provider := otellog.NewLoggerProvider(
+			otellog.WithProcessor(processor),
+		)
+
+		// Set global provider
+		global.SetLoggerProvider(provider)
+
+		// Create slog handler with level control
+		baseHandler := newLogFmtHandler(otelslog.NewHandler("common"))
+		handler := newOTLPLevelHandler(baseHandler)
+		otlpLogger = slog.New(handler)
 	})
 	return otlpLogger
 }

logger/otlp_handler.go

@@ -0,0 +1,48 @@
+package logger
+
+import (
+	"context"
+	"log/slog"
+)
+
+// otlpLevelHandler is a wrapper that enforces level checking for OTLP handlers.
+// This allows independent level control for OTLP output separate from stderr logging.
+type otlpLevelHandler struct {
+	next slog.Handler
+}
+
+// newOTLPLevelHandler creates a new OTLP level wrapper handler.
+func newOTLPLevelHandler(next slog.Handler) slog.Handler {
+	return &otlpLevelHandler{
+		next: next,
+	}
+}
+
+// Enabled checks if the log level should be processed by the OTLP handler.
+// It uses the OTLPLevel variable to determine if the record should be processed.
+func (h *otlpLevelHandler) Enabled(ctx context.Context, level slog.Level) bool {
+	return level >= OTLPLevel.Level()
+}
+
+// Handle processes the log record if the level is enabled.
+// If disabled by level checking, the record is silently dropped.
+func (h *otlpLevelHandler) Handle(ctx context.Context, r slog.Record) error {
+	if !h.Enabled(ctx, r.Level) {
+		return nil
+	}
+	return h.next.Handle(ctx, r)
+}
+
+// WithAttrs returns a new handler with the specified attributes added.
+func (h *otlpLevelHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return &otlpLevelHandler{
+		next: h.next.WithAttrs(attrs),
+	}
+}
+
+// WithGroup returns a new handler with the specified group name.
+func (h *otlpLevelHandler) WithGroup(name string) slog.Handler {
+	return &otlpLevelHandler{
+		next: h.next.WithGroup(name),
+	}
+}

metrics/metrics.go

@@ -0,0 +1,122 @@
+// Package metrics provides OpenTelemetry-native metrics with OTLP export support.
+//
+// This package implements a metrics system using the OpenTelemetry metrics data model
+// with OTLP export capabilities. It's designed for new applications that want to use
+// structured metrics export to observability backends.
+//
+// Key features:
+//   - OpenTelemetry native metric types (Counter, Histogram, Gauge, etc.)
+//   - OTLP export for sending metrics to observability backends
+//   - Resource detection and correlation with traces/logs
+//   - Graceful handling when OTLP configuration is not available
+//
+// Example usage:
+//
+//	// Initialize metrics along with tracing
+//	shutdown, err := tracing.InitTracer(ctx, cfg)
+//	if err != nil {
+//		log.Fatal(err)
+//	}
+//	defer shutdown(ctx)
+//
+//	// Get a meter and create instruments
+//	meter := metrics.GetMeter("my-service")
+//	counter, _ := meter.Int64Counter("requests_total")
+//	counter.Add(ctx, 1, metric.WithAttributes(attribute.String("method", "GET")))
+package metrics
+
+import (
+	"context"
+	"log/slog"
+	"sync"
+	"time"
+
+	"go.ntppool.org/common/internal/tracerconfig"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/metric"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+)
+
+var (
+	meterProvider metric.MeterProvider
+	setupOnce     sync.Once
+	setupErr      error
+)
+
+// Setup initializes the OpenTelemetry metrics provider with OTLP export.
+// This function uses the configuration stored by the tracing package and
+// creates a metrics provider that exports to the same OTLP endpoint.
+//
+// The function is safe to call multiple times - it will only initialize once.
+// If tracing configuration is not available, it returns a no-op provider that
+// doesn't export metrics.
+//
+// Returns an error only if there's a configuration problem. Missing tracing
+// configuration is handled gracefully with a warning log.
+func Setup(ctx context.Context) error {
+	setupOnce.Do(func() {
+		setupErr = initializeMetrics(ctx)
+	})
+	return setupErr
+}
+
+// GetMeter returns a named meter for creating metric instruments.
+// The meter uses the configured metrics provider, or the global provider
+// if metrics haven't been set up yet.
+//
+// This is the primary entry point for creating metric instruments in your application.
+func GetMeter(name string, opts ...metric.MeterOption) metric.Meter {
+	if meterProvider == nil {
+		// Return the global provider as fallback (no-op if not configured)
+		return otel.GetMeterProvider().Meter(name, opts...)
+	}
+	return meterProvider.Meter(name, opts...)
+}
+
+// initializeMetrics sets up the OpenTelemetry metrics provider with OTLP export.
+func initializeMetrics(ctx context.Context) error {
+	log := slog.Default()
+
+	// Check if tracing configuration is available
+	cfg, configCtx, factory := tracerconfig.GetMetricExporter()
+	if cfg == nil || configCtx == nil || factory == nil {
+		log.Warn("metrics setup: tracing configuration not available, using no-op provider")
+		// Set the global provider as fallback - metrics just won't be exported
+		meterProvider = otel.GetMeterProvider()
+		return nil
+	}
+
+	// Create OTLP metrics exporter
+	exporter, err := factory(ctx, cfg)
+	if err != nil {
+		log.Error("metrics setup: failed to create OTLP exporter", "error", err)
+		// Fall back to global provider
+		meterProvider = otel.GetMeterProvider()
+		return nil
+	}
+
+	// Create metrics provider with the exporter
+	provider := sdkmetric.NewMeterProvider(
+		sdkmetric.WithReader(sdkmetric.NewPeriodicReader(
+			exporter,
+			sdkmetric.WithInterval(15*time.Second),
+		)),
+	)
+
+	// Set the global provider
+	otel.SetMeterProvider(provider)
+	meterProvider = provider
+
+	log.Info("metrics setup: OTLP metrics provider initialized")
+	return nil
+}
+
+// Shutdown gracefully shuts down the metrics provider.
+// This should be called during application shutdown to ensure all metrics
+// are properly flushed and exported.
+func Shutdown(ctx context.Context) error {
+	if provider, ok := meterProvider.(*sdkmetric.MeterProvider); ok {
+		return provider.Shutdown(ctx)
+	}
+	return nil
+}

metrics/metrics_test.go

@@ -0,0 +1,296 @@
+package metrics
+
+import (
+	"context"
+	"os"
+	"testing"
+	"time"
+
+	"go.ntppool.org/common/internal/tracerconfig"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/metric/metricdata"
+)
+
+func TestSetup_NoConfiguration(t *testing.T) {
+	// Clear any existing configuration
+	tracerconfig.Clear()
+
+	ctx := context.Background()
+	err := Setup(ctx)
+	// Should not return an error even when no configuration is available
+	if err != nil {
+		t.Errorf("Setup() returned unexpected error: %v", err)
+	}
+
+	// Should be able to get a meter (even if it's a no-op)
+	meter := GetMeter("test-meter")
+	if meter == nil {
+		t.Error("GetMeter() returned nil")
+	}
+}
+
+func TestGetMeter(t *testing.T) {
+	// Clear any existing configuration
+	tracerconfig.Clear()
+
+	ctx := context.Background()
+	_ = Setup(ctx)
+
+	meter := GetMeter("test-service")
+	if meter == nil {
+		t.Fatal("GetMeter() returned nil")
+	}
+
+	// Test creating a counter instrument
+	counter, err := meter.Int64Counter("test_counter")
+	if err != nil {
+		t.Errorf("Failed to create counter: %v", err)
+	}
+
+	// Test using the counter (should not error even with no-op provider)
+	counter.Add(ctx, 1, metric.WithAttributes(attribute.String("test", "value")))
+}
+
+func TestSetup_MultipleCallsSafe(t *testing.T) {
+	// Clear any existing configuration
+	tracerconfig.Clear()
+
+	ctx := context.Background()
+
+	// Call Setup multiple times
+	err1 := Setup(ctx)
+	err2 := Setup(ctx)
+	err3 := Setup(ctx)
+
+	if err1 != nil {
+		t.Errorf("First Setup() call returned error: %v", err1)
+	}
+	if err2 != nil {
+		t.Errorf("Second Setup() call returned error: %v", err2)
+	}
+	if err3 != nil {
+		t.Errorf("Third Setup() call returned error: %v", err3)
+	}
+
+	// Should still be able to get meters
+	meter := GetMeter("test-meter")
+	if meter == nil {
+		t.Error("GetMeter() returned nil after multiple Setup() calls")
+	}
+}
+
+func TestSetup_WithConfiguration(t *testing.T) {
+	// Clear any existing configuration
+	tracerconfig.Clear()
+
+	ctx := context.Background()
+	config := &tracerconfig.Config{
+		ServiceName: "test-metrics-service",
+		Environment: "test",
+		Endpoint:    "localhost:4317", // Will likely fail to connect, but should set up provider
+	}
+
+	// Create a mock exporter factory that returns a working exporter
+	mockFactory := func(ctx context.Context, cfg *tracerconfig.Config) (sdkmetric.Exporter, error) {
+		// Create a simple in-memory exporter for testing
+		return &mockMetricExporter{}, nil
+	}
+
+	// Store configuration with mock factory
+	tracerconfig.Store(ctx, config, nil, mockFactory, nil)
+
+	// Setup metrics
+	err := Setup(ctx)
+	if err != nil {
+		t.Errorf("Setup() returned error: %v", err)
+	}
+
+	// Should be able to get a meter
+	meter := GetMeter("test-service")
+	if meter == nil {
+		t.Fatal("GetMeter() returned nil")
+	}
+
+	// Test creating and using instruments
+	counter, err := meter.Int64Counter("test_counter")
+	if err != nil {
+		t.Errorf("Failed to create counter: %v", err)
+	}
+
+	histogram, err := meter.Float64Histogram("test_histogram")
+	if err != nil {
+		t.Errorf("Failed to create histogram: %v", err)
+	}
+
+	gauge, err := meter.Int64UpDownCounter("test_gauge")
+	if err != nil {
+		t.Errorf("Failed to create gauge: %v", err)
+	}
+
+	// Use the instruments
+	counter.Add(ctx, 1, metric.WithAttributes(attribute.String("test", "value")))
+	histogram.Record(ctx, 1.5, metric.WithAttributes(attribute.String("test", "value")))
+	gauge.Add(ctx, 10, metric.WithAttributes(attribute.String("test", "value")))
+
+	// Test shutdown
+	err = Shutdown(ctx)
+	if err != nil {
+		t.Errorf("Shutdown() returned error: %v", err)
+	}
+}
+
+func TestSetup_WithRealOTLPConfig(t *testing.T) {
+	// Skip this test in short mode since it may try to make network connections
+	if testing.Short() {
+		t.Skip("Skipping integration test in short mode")
+	}
+
+	// Clear any existing configuration
+	tracerconfig.Clear()
+
+	// Set environment variables for OTLP configuration
+	originalEndpoint := os.Getenv("OTEL_EXPORTER_OTLP_ENDPOINT")
+	originalProtocol := os.Getenv("OTEL_EXPORTER_OTLP_PROTOCOL")
+
+	defer func() {
+		if originalEndpoint != "" {
+			os.Setenv("OTEL_EXPORTER_OTLP_ENDPOINT", originalEndpoint)
+		} else {
+			os.Unsetenv("OTEL_EXPORTER_OTLP_ENDPOINT")
+		}
+		if originalProtocol != "" {
+			os.Setenv("OTEL_EXPORTER_OTLP_PROTOCOL", originalProtocol)
+		} else {
+			os.Unsetenv("OTEL_EXPORTER_OTLP_PROTOCOL")
+		}
+	}()
+
+	os.Setenv("OTEL_EXPORTER_OTLP_ENDPOINT", "http://localhost:4318") // HTTP endpoint
+	os.Setenv("OTEL_EXPORTER_OTLP_PROTOCOL", "http/protobuf")
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	config := &tracerconfig.Config{
+		ServiceName: "test-metrics-e2e",
+		Environment: "test",
+		Endpoint:    "localhost:4318",
+	}
+
+	// Store configuration with real factory
+	tracerconfig.Store(ctx, config, nil, tracerconfig.CreateOTLPMetricExporter, nil)
+
+	// Setup metrics - this may fail if no OTLP collector is running, which is okay
+	err := Setup(ctx)
+	if err != nil {
+		t.Logf("Setup() returned error (expected if no OTLP collector): %v", err)
+	}
+
+	// Should still be able to get a meter
+	meter := GetMeter("test-service-e2e")
+	if meter == nil {
+		t.Fatal("GetMeter() returned nil")
+	}
+
+	// Create and use instruments
+	counter, err := meter.Int64Counter("e2e_test_counter")
+	if err != nil {
+		t.Errorf("Failed to create counter: %v", err)
+	}
+
+	// Add some metrics
+	for i := 0; i < 5; i++ {
+		counter.Add(ctx, 1, metric.WithAttributes(
+			attribute.String("iteration", string(rune('0'+i))),
+			attribute.String("test_type", "e2e"),
+		))
+	}
+
+	// Give some time for export (if collector is running)
+	time.Sleep(100 * time.Millisecond)
+
+	// Test shutdown
+	err = Shutdown(ctx)
+	if err != nil {
+		t.Logf("Shutdown() returned error (may be expected): %v", err)
+	}
+}
+
+func TestConcurrentMetricUsage(t *testing.T) {
+	// Clear any existing configuration
+	tracerconfig.Clear()
+
+	ctx := context.Background()
+	config := &tracerconfig.Config{
+		ServiceName: "concurrent-test",
+	}
+
+	// Use mock factory
+	mockFactory := func(ctx context.Context, cfg *tracerconfig.Config) (sdkmetric.Exporter, error) {
+		return &mockMetricExporter{}, nil
+	}
+
+	tracerconfig.Store(ctx, config, nil, mockFactory, nil)
+	Setup(ctx)
+
+	meter := GetMeter("concurrent-test")
+	counter, err := meter.Int64Counter("concurrent_counter")
+	if err != nil {
+		t.Fatalf("Failed to create counter: %v", err)
+	}
+
+	// Test concurrent metric usage
+	const numGoroutines = 10
+	const metricsPerGoroutine = 100
+
+	done := make(chan bool, numGoroutines)
+
+	for i := 0; i < numGoroutines; i++ {
+		go func(goroutineID int) {
+			for j := 0; j < metricsPerGoroutine; j++ {
+				counter.Add(ctx, 1, metric.WithAttributes(
+					attribute.Int("goroutine", goroutineID),
+					attribute.Int("iteration", j),
+				))
+			}
+			done <- true
+		}(i)
+	}
+
+	// Wait for all goroutines to complete
+	for i := 0; i < numGoroutines; i++ {
+		<-done
+	}
+
+	// Shutdown
+	err = Shutdown(ctx)
+	if err != nil {
+		t.Errorf("Shutdown() returned error: %v", err)
+	}
+}
+
+// mockMetricExporter is a simple mock exporter for testing
+type mockMetricExporter struct{}
+
+func (m *mockMetricExporter) Export(ctx context.Context, rm *metricdata.ResourceMetrics) error {
+	// Just pretend to export
+	return nil
+}
+
+func (m *mockMetricExporter) ForceFlush(ctx context.Context) error {
+	return nil
+}
+
+func (m *mockMetricExporter) Shutdown(ctx context.Context) error {
+	return nil
+}
+
+func (m *mockMetricExporter) Temporality(kind sdkmetric.InstrumentKind) metricdata.Temporality {
+	return metricdata.CumulativeTemporality
+}
+
+func (m *mockMetricExporter) Aggregation(kind sdkmetric.InstrumentKind) sdkmetric.Aggregation {
+	return sdkmetric.DefaultAggregationSelector(kind)
+}

metricsserver/metrics_test.go

@@ -15,11 +15,11 @@ import (
 
 func TestNew(t *testing.T) {
 	metrics := New()
-	
+
 	if metrics == nil {
 		t.Fatal("New returned nil")
 	}
-	
+
 	if metrics.r == nil {
 		t.Error("metrics registry is nil")
 	}
@@ -28,32 +28,32 @@ func TestNew(t *testing.T) {
 func TestRegistry(t *testing.T) {
 	metrics := New()
 	registry := metrics.Registry()
-	
+
 	if registry == nil {
 		t.Fatal("Registry() returned nil")
 	}
-	
+
 	if registry != metrics.r {
 		t.Error("Registry() did not return the metrics registry")
 	}
-	
+
 	// Test that we can register a metric
 	counter := prometheus.NewCounter(prometheus.CounterOpts{
 		Name: "test_counter",
 		Help: "A test counter",
 	})
-	
+
 	err := registry.Register(counter)
 	if err != nil {
 		t.Errorf("failed to register metric: %v", err)
 	}
-	
+
 	// Test that the metric is registered
 	metricFamilies, err := registry.Gather()
 	if err != nil {
 		t.Errorf("failed to gather metrics: %v", err)
 	}
-	
+
 	found := false
 	for _, mf := range metricFamilies {
 		if mf.GetName() == "test_counter" {
@@ -61,7 +61,7 @@ func TestRegistry(t *testing.T) {
 			break
 		}
 	}
-	
+
 	if !found {
 		t.Error("registered metric not found in registry")
 	}
@@ -69,7 +69,7 @@ func TestRegistry(t *testing.T) {
 
 func TestHandler(t *testing.T) {
 	metrics := New()
-	
+
 	// Register a test metric
 	counter := prometheus.NewCounterVec(
 		prometheus.CounterOpts{
@@ -80,40 +80,40 @@ func TestHandler(t *testing.T) {
 	)
 	metrics.Registry().MustRegister(counter)
 	counter.WithLabelValues("GET").Inc()
-	
+
 	// Test the handler
 	handler := metrics.Handler()
 	if handler == nil {
 		t.Fatal("Handler() returned nil")
 	}
-	
+
 	// Create a test request
 	req := httptest.NewRequest("GET", "/metrics", nil)
 	recorder := httptest.NewRecorder()
-	
+
 	// Call the handler
 	handler.ServeHTTP(recorder, req)
-	
+
 	// Check response
 	resp := recorder.Result()
 	defer resp.Body.Close()
-	
+
 	if resp.StatusCode != http.StatusOK {
 		t.Errorf("expected status 200, got %d", resp.StatusCode)
 	}
-	
+
 	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Fatalf("failed to read response body: %v", err)
 	}
-	
+
 	bodyStr := string(body)
-	
+
 	// Check for our test metric
 	if !strings.Contains(bodyStr, "test_requests_total") {
 		t.Error("test metric not found in metrics output")
 	}
-	
+
 	// Check for OpenMetrics format indicators
 	if !strings.Contains(bodyStr, "# TYPE") {
 		t.Error("metrics output missing TYPE comments")
@@ -122,7 +122,7 @@ func TestHandler(t *testing.T) {
 
 func TestListenAndServe(t *testing.T) {
 	metrics := New()
-	
+
 	// Register a test metric
 	counter := prometheus.NewCounterVec(
 		prometheus.CounterOpts{
@@ -133,46 +133,46 @@ func TestListenAndServe(t *testing.T) {
 	)
 	metrics.Registry().MustRegister(counter)
 	counter.WithLabelValues("GET").Inc()
-	
+
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	
+
 	// Start server in a goroutine
 	errCh := make(chan error, 1)
 	go func() {
 		// Use a high port number to avoid conflicts
 		errCh <- metrics.ListenAndServe(ctx, 9999)
 	}()
-	
+
 	// Give the server a moment to start
 	time.Sleep(100 * time.Millisecond)
-	
+
 	// Test metrics endpoint
 	resp, err := http.Get("http://localhost:9999/metrics")
 	if err != nil {
 		t.Fatalf("failed to GET /metrics: %v", err)
 	}
 	defer resp.Body.Close()
-	
+
 	if resp.StatusCode != http.StatusOK {
 		t.Errorf("expected status 200, got %d", resp.StatusCode)
 	}
-	
+
 	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Fatalf("failed to read response body: %v", err)
 	}
-	
+
 	bodyStr := string(body)
-	
+
 	// Check for our test metric
 	if !strings.Contains(bodyStr, "test_requests_total") {
 		t.Error("test metric not found in metrics output")
 	}
-	
+
 	// Cancel context to stop server
 	cancel()
-	
+
 	// Wait for server to stop
 	select {
 	case err := <-errCh:
@@ -186,21 +186,21 @@ func TestListenAndServe(t *testing.T) {
 
 func TestListenAndServeContextCancellation(t *testing.T) {
 	metrics := New()
-	
+
 	ctx, cancel := context.WithCancel(context.Background())
-	
+
 	// Start server
 	errCh := make(chan error, 1)
 	go func() {
 		errCh <- metrics.ListenAndServe(ctx, 9998)
 	}()
-	
+
 	// Give server time to start
 	time.Sleep(100 * time.Millisecond)
-	
+
 	// Cancel context
 	cancel()
-	
+
 	// Server should stop gracefully
 	select {
 	case err := <-errCh:
@@ -215,7 +215,7 @@ func TestListenAndServeContextCancellation(t *testing.T) {
 // Benchmark the metrics handler response time
 func BenchmarkMetricsHandler(b *testing.B) {
 	metrics := New()
-	
+
 	// Register some test metrics
 	for i := 0; i < 10; i++ {
 		counter := prometheus.NewCounter(prometheus.CounterOpts{
@@ -225,18 +225,18 @@ func BenchmarkMetricsHandler(b *testing.B) {
 		metrics.Registry().MustRegister(counter)
 		counter.Add(float64(i * 100))
 	}
-	
+
 	handler := metrics.Handler()
-	
+
 	b.ResetTimer()
-	
+
 	for i := 0; i < b.N; i++ {
 		req := httptest.NewRequest("GET", "/metrics", nil)
 		recorder := httptest.NewRecorder()
 		handler.ServeHTTP(recorder, req)
-		
+
 		if recorder.Code != http.StatusOK {
 			b.Fatalf("unexpected status code: %d", recorder.Code)
 		}
 	}
-}
+}

tracing/tracing.go

@@ -38,26 +38,23 @@ package tracing
 
 import (
 	"context"
-	"crypto/tls"
 	"crypto/x509"
 	"errors"
+	"log/slog"
 	"os"
 	"slices"
 	"time"
 
-	"go.ntppool.org/common/logger"
+	"go.ntppool.org/common/internal/tracerconfig"
 	"go.ntppool.org/common/version"
-	"google.golang.org/grpc/credentials"
 
 	"go.opentelemetry.io/contrib/exporters/autoexport"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
+	"go.opentelemetry.io/otel/log/global"
-	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
-	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
-	logglobal "go.opentelemetry.io/otel/log/global"
 	"go.opentelemetry.io/otel/propagation"
 	sdklog "go.opentelemetry.io/otel/sdk/log"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
 	"go.opentelemetry.io/otel/sdk/resource"
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
 	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
@@ -67,12 +64,25 @@ import (
 const (
 	// svcNameKey is the environment variable name that Service Name information will be read from.
 	svcNameKey = "OTEL_SERVICE_NAME"
-
-	otelExporterOTLPProtoEnvKey       = "OTEL_EXPORTER_OTLP_PROTOCOL"
-	otelExporterOTLPTracesProtoEnvKey = "OTEL_EXPORTER_OTLP_TRACES_PROTOCOL"
 )
 
-var errInvalidOTLPProtocol = errors.New("invalid OTLP protocol - should be one of ['grpc', 'http/protobuf']")
+// createOTLPLogExporter creates an OTLP log exporter using the provided configuration.
+// This function is used as the LogExporterFactory for the tracerconfig bridge.
+func createOTLPLogExporter(ctx context.Context, cfg *tracerconfig.Config) (sdklog.Exporter, error) {
+	return tracerconfig.CreateOTLPLogExporter(ctx, cfg)
+}
+
+// createOTLPMetricExporter creates an OTLP metric exporter using the provided configuration.
+// This function is used as the MetricExporterFactory for the tracerconfig bridge.
+func createOTLPMetricExporter(ctx context.Context, cfg *tracerconfig.Config) (sdkmetric.Exporter, error) {
+	return tracerconfig.CreateOTLPMetricExporter(ctx, cfg)
+}
+
+// createOTLPTraceExporter creates an OTLP trace exporter using the provided configuration.
+// This function is used as the TraceExporterFactory for the tracerconfig bridge.
+func createOTLPTraceExporter(ctx context.Context, cfg *tracerconfig.Config) (sdktrace.SpanExporter, error) {
+	return tracerconfig.CreateOTLPTraceExporter(ctx, cfg)
+}
 
 // https://github.com/open-telemetry/opentelemetry-go/blob/main/exporters/otlp/otlptrace/otlptracehttp/example_test.go
 
@@ -98,10 +108,9 @@ func Start(ctx context.Context, spanName string, opts ...trace.SpanStartOption)
 	return Tracer().Start(ctx, spanName, opts...)
 }
 
-// GetClientCertificate defines a function type for providing client certificates for mutual TLS.
+// GetClientCertificate is an alias for the type defined in tracerconfig.
-// This is used when exporting telemetry data to secured OTLP endpoints that require
+// This maintains backward compatibility for existing code.
-// client certificate authentication.
+type GetClientCertificate = tracerconfig.GetClientCertificate
-type GetClientCertificate func(*tls.CertificateRequestInfo) (*tls.Certificate, error)
 
 // TracerConfig provides configuration options for OpenTelemetry tracing setup.
 // It supplements standard OpenTelemetry environment variables with additional
@@ -143,7 +152,18 @@ func SetupSDK(ctx context.Context, cfg *TracerConfig) (shutdown TpShutdownFunc,
 		cfg = &TracerConfig{}
 	}
 
-	log := logger.Setup()
+	// Store configuration for use by logger and metrics packages via bridge
+	bridgeConfig := &tracerconfig.Config{
+		ServiceName:         cfg.ServiceName,
+		Environment:         cfg.Environment,
+		Endpoint:            cfg.Endpoint,
+		EndpointURL:         cfg.EndpointURL,
+		CertificateProvider: cfg.CertificateProvider,
+		RootCAs:             cfg.RootCAs,
+	}
+	tracerconfig.Store(ctx, bridgeConfig, createOTLPLogExporter, createOTLPMetricExporter, createOTLPTraceExporter)
+
+	log := slog.Default()
 
 	if serviceName := os.Getenv(svcNameKey); len(serviceName) == 0 {
 		if len(cfg.ServiceName) > 0 {
@@ -184,13 +204,21 @@ func SetupSDK(ctx context.Context, cfg *TracerConfig) (shutdown TpShutdownFunc,
 
 	var shutdownFuncs []func(context.Context) error
 	shutdown = func(ctx context.Context) error {
+		// Force flush the global logger provider before shutting down anything else
+		if loggerProvider := global.GetLoggerProvider(); loggerProvider != nil {
+			if sdkProvider, ok := loggerProvider.(*sdklog.LoggerProvider); ok {
+				if flushErr := sdkProvider.ForceFlush(ctx); flushErr != nil {
+					log.Warn("logger provider force flush failed", "err", flushErr)
+				}
+			}
+		}
+
 		var err error
 		// need to shutdown the providers first,
 		// exporters after which is the opposite
 		// order they are setup.
 		slices.Reverse(shutdownFuncs)
 		for _, fn := range shutdownFuncs {
-			// log.Warn("shutting down", "fn", fn)
 			err = errors.Join(err, fn(ctx))
 		}
 		shutdownFuncs = nil
@@ -212,9 +240,9 @@ func SetupSDK(ctx context.Context, cfg *TracerConfig) (shutdown TpShutdownFunc,
 
 	switch os.Getenv("OTEL_TRACES_EXPORTER") {
 	case "":
-		spanExporter, err = newOLTPExporter(ctx, cfg)
+		spanExporter, err = createOTLPTraceExporter(ctx, bridgeConfig)
 	case "otlp":
-		spanExporter, err = newOLTPExporter(ctx, cfg)
+		spanExporter, err = createOTLPTraceExporter(ctx, bridgeConfig)
 	default:
 		// log.Debug("OTEL_TRACES_EXPORTER", "fallback", os.Getenv("OTEL_TRACES_EXPORTER"))
 		spanExporter, err = autoexport.NewSpanExporter(ctx)
@@ -225,13 +253,6 @@ func SetupSDK(ctx context.Context, cfg *TracerConfig) (shutdown TpShutdownFunc,
 	}
 	shutdownFuncs = append(shutdownFuncs, spanExporter.Shutdown)
 
-	logExporter, err := autoexport.NewLogExporter(ctx)
-	if err != nil {
-		handleErr(err)
-		return
-	}
-	shutdownFuncs = append(shutdownFuncs, logExporter.Shutdown)
-
 	// Set up trace provider.
 	tracerProvider, err := newTraceProvider(spanExporter, res)
 	if err != nil {
@@ -241,19 +262,6 @@ func SetupSDK(ctx context.Context, cfg *TracerConfig) (shutdown TpShutdownFunc,
 	shutdownFuncs = append(shutdownFuncs, tracerProvider.Shutdown)
 	otel.SetTracerProvider(tracerProvider)
 
-	logProvider := sdklog.NewLoggerProvider(sdklog.WithResource(res),
-		sdklog.WithProcessor(
-			sdklog.NewBatchProcessor(logExporter, sdklog.WithExportBufferSize(10)),
-		),
-	)
-
-	logglobal.SetLoggerProvider(logProvider)
-	shutdownFuncs = append(shutdownFuncs, func(ctx context.Context) error {
-		logProvider.ForceFlush(ctx)
-		return logProvider.Shutdown(ctx)
-	},
-	)
-
 	if err != nil {
 		handleErr(err)
 		return
@@ -262,74 +270,6 @@ func SetupSDK(ctx context.Context, cfg *TracerConfig) (shutdown TpShutdownFunc,
 	return
 }
 
-func newOLTPExporter(ctx context.Context, cfg *TracerConfig) (sdktrace.SpanExporter, error) {
-	log := logger.Setup()
-
-	var tlsConfig *tls.Config
-
-	if cfg.CertificateProvider != nil {
-		tlsConfig = &tls.Config{
-			GetClientCertificate: cfg.CertificateProvider,
-			RootCAs:              cfg.RootCAs,
-		}
-	}
-
-	proto := os.Getenv(otelExporterOTLPTracesProtoEnvKey)
-	if proto == "" {
-		proto = os.Getenv(otelExporterOTLPProtoEnvKey)
-	}
-
-	// Fallback to default, http/protobuf.
-	if proto == "" {
-		proto = "http/protobuf"
-	}
-
-	var client otlptrace.Client
-
-	switch proto {
-	case "grpc":
-		opts := []otlptracegrpc.Option{
-			otlptracegrpc.WithCompressor("gzip"),
-		}
-		if tlsConfig != nil {
-			opts = append(opts, otlptracegrpc.WithTLSCredentials(credentials.NewTLS(tlsConfig)))
-		}
-		if len(cfg.Endpoint) > 0 {
-			log.Info("adding option", "Endpoint", cfg.Endpoint)
-			opts = append(opts, otlptracegrpc.WithEndpoint(cfg.Endpoint))
-		}
-		if len(cfg.EndpointURL) > 0 {
-			log.Info("adding option", "EndpointURL", cfg.EndpointURL)
-			opts = append(opts, otlptracegrpc.WithEndpointURL(cfg.EndpointURL))
-		}
-
-		client = otlptracegrpc.NewClient(opts...)
-	case "http/protobuf", "http/json":
-		opts := []otlptracehttp.Option{
-			otlptracehttp.WithCompression(otlptracehttp.GzipCompression),
-		}
-		if tlsConfig != nil {
-			opts = append(opts, otlptracehttp.WithTLSClientConfig(tlsConfig))
-		}
-		if len(cfg.Endpoint) > 0 {
-			opts = append(opts, otlptracehttp.WithEndpoint(cfg.Endpoint))
-		}
-		if len(cfg.EndpointURL) > 0 {
-			opts = append(opts, otlptracehttp.WithEndpointURL(cfg.EndpointURL))
-		}
-
-		client = otlptracehttp.NewClient(opts...)
-	default:
-		return nil, errInvalidOTLPProtocol
-	}
-
-	exporter, err := otlptrace.New(ctx, client)
-	if err != nil {
-		log.ErrorContext(ctx, "creating OTLP trace exporter", "err", err)
-	}
-	return exporter, err
-}
-
 func newTraceProvider(traceExporter sdktrace.SpanExporter, res *resource.Resource) (*sdktrace.TracerProvider, error) {
 	traceProvider := sdktrace.NewTracerProvider(
 		sdktrace.WithResource(res),

version/version.go

@@ -10,8 +10,18 @@
 //	  -X go.ntppool.org/common/version.buildTime=2023-01-01T00:00:00Z \
 //	  -X go.ntppool.org/common/version.gitVersion=abc123"
 //
-// The package also automatically extracts build information from Go's debug.BuildInfo
+// Build time supports both Unix epoch timestamps and RFC3339 format:
-// when available, providing fallback values for VCS time and revision.
+//
+//	# Unix epoch (simpler, recommended)
+//	go build -ldflags "-X go.ntppool.org/common/version.buildTime=$(date +%s)"
+//
+//	# RFC3339 format
+//	go build -ldflags "-X go.ntppool.org/common/version.buildTime=$(date -u +%Y-%m-%dT%H:%M:%SZ)"
+//
+// Both formats are automatically converted to RFC3339 for consistent output. The buildTime
+// parameter takes priority over Git commit time. If buildTime is not specified, the package
+// automatically extracts build information from Go's debug.BuildInfo when available,
+// providing fallback values for VCS time and revision.
 package version
 
 import (
@@ -19,7 +29,9 @@ import (
 	"log/slog"
 	"runtime"
 	"runtime/debug"
+	"strconv"
 	"strings"
+	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/spf13/cobra"
@@ -30,7 +42,7 @@ import (
 // If not set, defaults to "dev-snapshot". The version should follow semantic versioning.
 var (
 	VERSION     string // Semantic version (e.g., "1.0.0" or "v1.0.0")
-	buildTime   string // Build timestamp (RFC3339 format)
+	buildTime   string // Build timestamp (Unix epoch or RFC3339, normalized to RFC3339)
 	gitVersion  string // Git commit hash
 	gitModified bool   // Whether the working tree was modified during build
 )
@@ -38,6 +50,28 @@ var (
 // info holds the consolidated version information extracted from build variables and debug.BuildInfo.
 var info Info
 
+// parseBuildTime converts a build time string to RFC3339 format.
+// Supports both Unix epoch timestamps (numeric strings) and RFC3339 format.
+// Returns the input unchanged if it cannot be parsed as either format.
+func parseBuildTime(s string) string {
+	if s == "" {
+		return s
+	}
+
+	// Try parsing as Unix epoch timestamp (numeric string)
+	if epoch, err := strconv.ParseInt(s, 10, 64); err == nil {
+		return time.Unix(epoch, 0).UTC().Format(time.RFC3339)
+	}
+
+	// Try parsing as RFC3339 to validate format
+	if _, err := time.Parse(time.RFC3339, s); err == nil {
+		return s // Already in RFC3339 format
+	}
+
+	// Return original string if neither format works (graceful fallback)
+	return s
+}
+
 // Info represents structured version and build information.
 // This struct is used for JSON serialization and programmatic access to build metadata.
 type Info struct {
@@ -48,6 +82,7 @@ type Info struct {
 }
 
 func init() {
+	buildTime = parseBuildTime(buildTime)
 	info.BuildTime = buildTime
 	info.GitRev = gitVersion
 
@@ -67,9 +102,9 @@ func init() {
 			switch h.Key {
 			case "vcs.time":
 				if len(buildTime) == 0 {
-					buildTime = h.Value
+					buildTime = parseBuildTime(h.Value)
+					info.BuildTime = buildTime
 				}
-				info.BuildTime = h.Value
 			case "vcs.revision":
 				// https://blog.carlmjohnson.net/post/2023/golang-git-hash-how-to/
 				// todo: use BuildInfo.Main.Version if revision is empty

version/version_test.go

@@ -309,3 +309,106 @@ func BenchmarkCheckVersionDevSnapshot(b *testing.B) {
 		_ = CheckVersion(version, minimum)
 	}
 }
+
+func TestParseBuildTime(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "Unix epoch timestamp",
+			input:    "1672531200", // 2023-01-01T00:00:00Z
+			expected: "2023-01-01T00:00:00Z",
+		},
+		{
+			name:     "Unix epoch zero",
+			input:    "0",
+			expected: "1970-01-01T00:00:00Z",
+		},
+		{
+			name:     "Valid RFC3339 format",
+			input:    "2023-12-25T15:30:45Z",
+			expected: "2023-12-25T15:30:45Z",
+		},
+		{
+			name:     "RFC3339 with timezone",
+			input:    "2023-12-25T10:30:45-05:00",
+			expected: "2023-12-25T10:30:45-05:00",
+		},
+		{
+			name:     "Empty string",
+			input:    "",
+			expected: "",
+		},
+		{
+			name:     "Invalid format - return unchanged",
+			input:    "not-a-date",
+			expected: "not-a-date",
+		},
+		{
+			name:     "Invalid timestamp - return unchanged",
+			input:    "invalid-timestamp",
+			expected: "invalid-timestamp",
+		},
+		{
+			name:     "Partial date - return unchanged",
+			input:    "2023-01-01",
+			expected: "2023-01-01",
+		},
+		{
+			name:     "Negative epoch - should work",
+			input:    "-1",
+			expected: "1969-12-31T23:59:59Z",
+		},
+		{
+			name:     "Large epoch timestamp",
+			input:    "4102444800", // 2100-01-01T00:00:00Z
+			expected: "2100-01-01T00:00:00Z",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := parseBuildTime(tt.input)
+			if result != tt.expected {
+				t.Errorf("parseBuildTime(%q) = %q, expected %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestParseBuildTimeConsistency(t *testing.T) {
+	// Test that calling parseBuildTime multiple times with the same input returns the same result
+	testInputs := []string{
+		"1672531200",
+		"2023-01-01T00:00:00Z",
+		"invalid-date",
+		"",
+	}
+
+	for _, input := range testInputs {
+		result1 := parseBuildTime(input)
+		result2 := parseBuildTime(input)
+		if result1 != result2 {
+			t.Errorf("parseBuildTime(%q) not consistent: %q != %q", input, result1, result2)
+		}
+	}
+}
+
+func BenchmarkParseBuildTime(b *testing.B) {
+	inputs := []string{
+		"1672531200",                 // Unix epoch
+		"2023-01-01T00:00:00Z",      // RFC3339
+		"invalid-timestamp",          // Invalid
+		"",                          // Empty
+	}
+
+	for _, input := range inputs {
+		b.Run(input, func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				_ = parseBuildTime(input)
+			}
+		})
+	}
+}