From ebd069586290a4ead83f216f20d35ad494abd49f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ask=20Bj=C3=B8rn=20Hansen?= <ask@develooper.com>
Date: Sat, 8 Jul 2023 12:32:49 -0700
Subject: [PATCH] Add version package

---
 version/version.go | 124 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 version/version.go

diff --git a/version/version.go b/version/version.go
new file mode 100644
index 0000000..855cccc
--- /dev/null
+++ b/version/version.go
@@ -0,0 +1,124 @@
+package version
+
+import (
+	"fmt"
+	"runtime"
+	"runtime/debug"
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/spf13/cobra"
+	"go.ntppool.org/common/logger"
+	"golang.org/x/mod/semver"
+)
+
+// VERSION has the current software version (set in the build process)
+var VERSION string
+var buildTime string
+var gitVersion string
+var gitModified bool
+
+var info Info
+
+type Info struct {
+	Version   string `json:",omitempty"`
+	GitRev    string `json:",omitempty"`
+	BuildTime string `json:",omitempty"`
+}
+
+func init() {
+
+	info.BuildTime = buildTime
+	info.GitRev = gitVersion
+
+	if len(VERSION) == 0 {
+		VERSION = "dev-snapshot"
+	} else {
+		if !strings.HasPrefix(VERSION, "v") {
+			VERSION = "v" + VERSION
+		}
+		if !semver.IsValid(VERSION) {
+			logger.Setup().Warn("invalid version number", "version", VERSION)
+		}
+	}
+	if bi, ok := debug.ReadBuildInfo(); ok {
+		for _, h := range bi.Settings {
+			// logger.Setup().Info("build info", "k", h.Key, "v", h.Value)
+			switch h.Key {
+			case "vcs.time":
+				buildTime = h.Value
+				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
+				gitVersion = h.Value
+				info.GitRev = h.Value
+			case "vcs.modified":
+				if h.Value == "true" {
+					gitModified = true
+				}
+			}
+		}
+	}
+
+	info.Version = VERSION
+
+	Version()
+}
+
+func VersionCmd(name string) *cobra.Command {
+	versionCmd := &cobra.Command{
+		Use:   "version",
+		Short: "Print version and build information",
+		Run: func(cmd *cobra.Command, args []string) {
+			ver := Version()
+			fmt.Printf("%s %s\n", name, ver)
+		},
+	}
+	return versionCmd
+}
+
+func RegisterMetric(registry prometheus.Registerer) {
+	buildInfo := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "build_info",
+			Help: "Build information",
+		},
+		[]string{"version"},
+	)
+	registry.MustRegister(buildInfo)
+	buildInfo.WithLabelValues(Version()).Set(1)
+}
+
+var v string
+
+func VersionInfo() Info {
+	return info
+}
+
+func Version() string {
+	if len(v) > 0 {
+		return v
+	}
+	extra := []string{}
+	if len(buildTime) > 0 {
+		extra = append(extra, buildTime)
+	}
+	extra = append(extra, runtime.Version())
+
+	v := VERSION
+	if len(gitVersion) > 0 {
+		g := gitVersion
+		if len(g) > 7 {
+			g = g[0:7]
+		}
+		v += "/" + g
+		if gitModified {
+			v += "-M"
+		}
+
+	}
+
+	v = fmt.Sprintf("%s (%s)", v, strings.Join(extra, ", "))
+	return v
+}