move implementation to internal/ directory (#828)

internal/version/version.go

@@ -0,0 +1,52 @@
+package version
+
+import (
+	"fmt"
+	"runtime"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	zreplVersion string // set by build infrastructure
+)
+
+type ZreplVersionInformation struct {
+	Version         string
+	RuntimeGo       string
+	RuntimeGOOS     string
+	RuntimeGOARCH   string
+	RUNTIMECompiler string
+}
+
+func NewZreplVersionInformation() *ZreplVersionInformation {
+	return &ZreplVersionInformation{
+		Version:         zreplVersion,
+		RuntimeGo:       runtime.Version(),
+		RuntimeGOOS:     runtime.GOOS,
+		RuntimeGOARCH:   runtime.GOARCH,
+		RUNTIMECompiler: runtime.Compiler,
+	}
+}
+
+func (i *ZreplVersionInformation) String() string {
+	return fmt.Sprintf("zrepl version=%s go=%s GOOS=%s GOARCH=%s Compiler=%s",
+		i.Version, i.RuntimeGo, i.RuntimeGOOS, i.RuntimeGOARCH, i.RUNTIMECompiler)
+}
+
+var prometheusMetric = prometheus.NewGauge(
+	prometheus.GaugeOpts{
+		Namespace: "zrepl",
+		Name:      "start_time",
+		Help:      "zrepl daemon start time and version",
+		ConstLabels: map[string]string{
+			"raw":          zreplVersion,
+			"version_info": NewZreplVersionInformation().String(),
+		},
+	},
+)
+
+func PrometheusRegister(r prometheus.Registerer) {
+	r.MustRegister(prometheusMetric)
+	prometheusMetric.SetToCurrentTime()
+}