version CLI flag

Makefile

@@ -1,6 +1,7 @@
 # this is the what ends up in the RPM "Version" field and it is also used as suffix for the built binaries
 # if you want to commit to OBS it must be a remotely available Git reference
-VERSION ?= $(shell git rev-parse --short HEAD)
+VERSION ?= $(shell git describe --tags --abbrev=0)dev+git.$(shell git show -s --format=%ct.%h HEAD)
+DATE = $(shell date --iso-8601=seconds)
 
 # we only use this to comply with RPM changelog conventions at SUSE
 AUTHOR ?= shap-staff@suse.de
@@ -25,7 +26,7 @@ build-all: clean-bin $(ARCHS)
 
 $(ARCHS):
 	@mkdir -p build/bin
-	CGO_ENABLED=0 GOOS=linux GOARCH=$@ go build -trimpath -ldflags "-s -w -X main.version=$(VERSION)" -o build/bin/ha_cluster_exporter-$(VERSION)-$@
+	CGO_ENABLED=0 GOOS=linux GOARCH=$@ go build -trimpath -ldflags "-s -w -X main.version=$(VERSION) -X main.buildDate=$(DATE)" -o build/bin/ha_cluster_exporter-$(VERSION)-$@
 
 install:
 	go install

ha_cluster_exporter.go

@@ -3,6 +3,8 @@ package main
 import (
 	"fmt"
 	"net/http"
+	"os"
+	"runtime"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -17,6 +19,17 @@ import (
 	"github.com/ClusterLabs/ha_cluster_exporter/internal"
 )
 
+var (
+	// the released version
+	version string
+	// the time the binary was built
+	buildDate string
+	// global --help flag
+	helpFlag *bool
+	// global --version flag
+	versionFlag *bool
+)
+
 func init() {
 	config.SetConfigName("ha_cluster_exporter")
 	config.AddConfigPath("./")
@@ -35,19 +48,35 @@ func init() {
 	flag.String("sbd-config-path", "/etc/sysconfig/sbd", "path to sbd configuration")
 	flag.String("drbdsetup-path", "/sbin/drbdsetup", "path to drbdsetup executable")
 	flag.String("drbdsplitbrain-path", "/var/run/drbd/splitbrain", "path to drbd splitbrain hooks temporary files")
-	flag.Bool("enable-timestamps", false, "Add the timestamp to every metric line (hint: don't do this unless you really know what you are doing)")
+	flag.Bool("enable-timestamps", false, "Add the timestamp to every metric line")
+	flag.CommandLine.MarkDeprecated("enable-timestamps", "server-side metric timestamping is discouraged by Prometheus best-practices and should be avoided")
+	flag.CommandLine.SortFlags = false
 
 	err := config.BindPFlags(flag.CommandLine)
 	if err != nil {
-		log.Errorf("Could not bind config to CLI flags: %v", err)
+		log.Fatalf("Could not bind config to CLI flags: %v", err)
 	}
+
+	helpFlag = flag.BoolP("help", "h", false, "show this help message")
+	versionFlag = flag.Bool("version", false, "show version and build information")
 }
 
 func main() {
-	var err error
-
 	flag.Parse()
 
+	switch {
+	case *helpFlag:
+		showHelp()
+	case *versionFlag:
+		showVersion()
+	default:
+		run()
+	}
+}
+
+func run() {
+	var err error
+
 	err = config.ReadInConfig()
 	if err != nil {
 		log.Warn(err)
@@ -112,3 +141,16 @@ func main() {
 	log.Infof("Serving metrics on %s", fullListenAddress)
 	log.Fatal(http.ListenAndServe(fullListenAddress, nil))
 }
+
+func showHelp() {
+	flag.Usage()
+	os.Exit(0)
+}
+
+func showVersion() {
+	if buildDate == "" {
+		buildDate = "at unknown time"
+	}
+	fmt.Printf("version %s\nbuilt with %s %s/%s %s\n", version, runtime.Version(), runtime.GOOS, runtime.GOARCH, buildDate)
+	os.Exit(0)
+}

packaging/obs/prometheus-ha_cluster_exporter.spec

@@ -44,12 +44,13 @@ Prometheus exporter for Pacemaker HA clusters metrics
 %setup -q -T -D -a 1 # unpack go dependencies in vendor.tar.gz, which was prepared by the source services
 
 %define shortname ha_cluster_exporter
+%define build_date %(date --iso-8601=seconds)
 
 %build
 
 export CGO_ENABLED=0
 go build -mod=vendor \
-         -ldflags="-s -w -X main.version=%{version}" \
+         -ldflags="-s -w -X main.version=%{version} -X main.buildDate=%{build_date}" \
          -o %{shortname}
 
 %install