--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=$(VERSION)" -o build/bin/sap_host_exporter-$(VERSION)-$@
+	CGO_ENABLED=0 GOOS=linux GOARCH=$@ go build -trimpath -ldflags "-s -w -X main.version=$(VERSION) -X main.buildDate=$(DATE)" -o build/bin/sap_host_exporter-$(VERSION)-$@
 
 install:
 	go install

internal/config/config.go

@@ -9,10 +9,10 @@ import (
 	"github.com/spf13/viper"
 )
 
-func New() (*viper.Viper, error) {
+func New(flagSet *flag.FlagSet) (*viper.Viper, error) {
 	config := viper.New()
 
-	err := config.BindPFlags(flag.CommandLine)
+	err := config.BindPFlags(flagSet)
 	if err != nil {
 		return nil, errors.Wrap(err, "could not bind config to CLI flags")
 	}

internal/config/loader.go

@@ -47,5 +47,7 @@ func loadConfigurationFromFile(config *viper.Viper, path string) error {
 		return errors.Wrap(err, "could not read file")
 	}
 
+	log.Info("Using config file: ", path)
+
 	return nil
 }

main.go

@@ -3,6 +3,8 @@ package main
 import (
 	"fmt"
 	"net/http"
+	"os"
+	"runtime"
 
 	"github.com/SUSE/sap_host_exporter/collector/registry"
 	"github.com/SUSE/sap_host_exporter/collector/start_service"
@@ -16,26 +18,52 @@ import (
 	flag "github.com/spf13/pflag"
 )
 
+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() {
 	flag.String("port", "9680", "The port number to listen on for HTTP requests")
 	flag.String("address", "0.0.0.0", "The address to listen on for HTTP requests")
 	flag.String("log-level", "info", "The minimum logging level; levels are, in ascending order: debug, info, warn, error")
 	flag.String("sap-control-url", "localhost:50013", "The URL of the SAPControl SOAP web service, e.g. $HOST:$PORT")
 	flag.String("sap-control-uds", "", "The path to the SAPControl Unix Domain Socket. If set, this will be used instead of the URL.")
 	flag.StringP("config", "c", "", "The path to a custom configuration file. NOTE: it must be in yaml format.")
+	flag.CommandLine.SortFlags = false
+
+	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()
 
-	config, err := config.New()
+	switch {
+	case *helpFlag:
+		showHelp()
+	case *versionFlag:
+		showVersion()
+	default:
+		run()
+	}
+}
+
+func run() {
+	var err error
+
+	globalConfig, err := config.New(flag.CommandLine)
 	if err != nil {
 		log.Fatalf("Could not initialize config: %s", err)
 	}
 
-	client := sapcontrol.NewSoapClient(config)
+	client := sapcontrol.NewSoapClient(globalConfig)
 	webService := sapcontrol.NewWebService(client)
 	currentSapInstance, err := webService.GetCurrentInstance()
 	if err != nil {
@@ -62,11 +90,25 @@ func main() {
 		prometheus.Unregister(prometheus.NewGoCollector())
 	}
 
-	fullListenAddress := fmt.Sprintf("%s:%s", config.Get("address"), config.Get("port"))
+	fullListenAddress := fmt.Sprintf("%s:%s", globalConfig.Get("address"), globalConfig.Get("port"))
 
 	http.HandleFunc("/", internal.Landing)
 	http.Handle("/metrics", promhttp.Handler())
 
 	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-sap_host_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 sap_host_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