add tracing

geoipapi.go

@@ -1,16 +1,25 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 	"log"
 	"net"
 	"net/http"
 	"os"
+	"os/signal"
 	"path/filepath"
 	"strings"
+	"syscall"
+	"time"
 
 	"github.com/oschwald/geoip2-golang"
+	"go.ntppool.org/common/logger"
+	"go.ntppool.org/common/tracing"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
 )
 
 type geoType uint8
@@ -25,26 +34,39 @@ var dbFiles map[geoType][]string
 
 func init() {
 	dbFiles = map[geoType][]string{
-		countryDB: []string{"GeoIP2-Country.mmdb", "GeoLite2-Country.mmdb"},
-		asnDB:     []string{"GeoIP2-ISP.mmdb"},
-		cityDB:    []string{"GeoIP2-City.mmdb", "GeoLite2-City.mmdb"},
+		countryDB: {"GeoIP2-Country.mmdb", "GeoLite2-Country.mmdb"},
+		asnDB:     {"GeoIP2-ISP.mmdb"},
+		cityDB:    {"GeoIP2-City.mmdb", "GeoLite2-City.mmdb"},
 	}
 }
 
 func main() {
+	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, os.Kill, syscall.SIGTERM)
+	defer cancel()
+
+	log := logger.FromContext(ctx)
+
+	tpShutdown, err := tracing.SetupSDK(ctx, &tracing.TracerConfig{
+		ServiceName: "geoipapi",
+	})
+	if err != nil {
+		log.ErrorContext(ctx, "could not setup tracing", "err", err)
+		os.Exit(2)
+	}
+	defer tpShutdown(context.Background()) // todo: with timeout
 
 	rdr, err := open(cityDB)
 	if err != nil {
-		log.Fatalf("opening db: %s", err)
+		log.ErrorContext(ctx, "could not open geodb", "err", err)
+		os.Exit(3)
 	}
 
 	if len(os.Args) > 1 {
 		for _, str := range os.Args[1:] {
-			log.Printf("%q", str)
 			ip := net.ParseIP(str)
 			city, err := rdr.City(ip)
 			if err != nil {
-				log.Printf("error looking up %q: %s", ip, err)
+				fmt.Printf("error looking up %q\n: %s", ip, err)
 				continue
 			}
 			fmt.Printf("%s: %s\n", ip, city.Country.IsoCode)
@@ -52,18 +74,38 @@ func main() {
 		os.Exit(0)
 	}
 
-	err = setupHTTP(rdr)
+	err = setupHTTP(ctx)
 	if err != nil {
-		log.Fatalf("http: %s", err)
+		log.ErrorContext(ctx, "http server", "err", err)
 	}
 }
 
-func setupHTTP(rdr *geoip2.Reader) error {
+func setupHTTP(ctx context.Context) error {
 	mux := http.NewServeMux()
 	mux.HandleFunc("/api/country", handleCountry)
 	mux.HandleFunc("/api/json", handleJSON)
 	mux.HandleFunc("/healthz", handleHealth)
-	return http.ListenAndServe(":8009", mux)
+
+	srv := &http.Server{
+		Addr:         ":8009",
+		BaseContext:  func(_ net.Listener) context.Context { return ctx },
+		ReadTimeout:  time.Second,
+		WriteTimeout: 10 * time.Second,
+		Handler:      otelhttp.NewHandler(mux, "geoipapi"),
+	}
+	srvErr := make(chan error, 1)
+	go func() {
+		srvErr <- srv.ListenAndServe()
+	}()
+
+	select {
+	case err := <-srvErr:
+		// Error when starting HTTP server.
+		return err
+	case <-ctx.Done():
+	}
+
+	return srv.Shutdown(context.Background())
 }
 
 func getCityIP(ip net.IP) (*geoip2.City, error) {
@@ -80,8 +122,10 @@ func getCityIP(ip net.IP) (*geoip2.City, error) {
 }
 
 func getCity(req *http.Request) (*geoip2.City, error) {
+	span := trace.SpanFromContext(req.Context())
 	req.ParseForm()
 	ipStr := req.FormValue("ip")
+	span.SetAttributes(attribute.String("ip", ipStr))
 	ip := net.ParseIP(ipStr)
 	if ip == nil {
 		return nil, fmt.Errorf("missing IP address")
@@ -133,7 +177,6 @@ func handleHealth(w http.ResponseWriter, req *http.Request) {
 }
 
 func open(t geoType) (*geoip2.Reader, error) {
-
 	dir := findDB()
 
 	var fileName string