Capture build information and print with -version

Makefile

@@ -17,16 +17,30 @@ TEST_ARTIFACTS = prometheus prometheus.build search_index
 
 include Makefile.INCLUDE
 
+REV        := $(shell git rev-parse --short HEAD)
+BRANCH     := $(shell git rev-parse --abbrev-ref HEAD)
+HOSTNAME   := $(shell hostname)
+BUILD_DATE := $(shell date)
+BUILDFLAGS := -ldflags \
+	      " -X main.buildVersion $(REV)\
+		-X main.buildBranch $(BRANCH)\
+		-X main.buildUser $(USER)@$(HOSTNAME)\
+		-X main.buildDate '$(BUILD_DATE)'\
+		-X main.goVersion '$(GO_VERSION)'\
+		-X main.leveldbVersion '$(LEVELDB_VERSION)'\
+		-X main.protobufVersion '$(PROTOCOL_BUFFERS_VERSION)'\
+		-X main.snappyVersion '$(SNAPPY_VERSION)'"
+
 all: test
 
 advice:
 	go tool vet .
 
 binary: build
-	go build -o prometheus.build
+	go build $(BUILDFLAGS) -o prometheus.build
 
 build: preparation model web
-	go build .
+	go build $(BUILDFLAGS) .
 
 clean:
 	$(MAKE) -C build clean

build_info.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"text/template"
+)
+
+// Build information. Populated by Makefile.
+var (
+	buildVersion    string
+	buildBranch     string
+	buildUser       string
+	buildDate       string
+	goVersion       string
+	leveldbVersion  string
+	protobufVersion string
+	snappyVersion   string
+)
+
+var BuildInfo = map[string]string{
+	"version":          buildVersion,
+	"branch":           buildBranch,
+	"user":             buildUser,
+	"date":             buildDate,
+	"go_version":       goVersion,
+	"leveldb_version":  leveldbVersion,
+	"protobuf_version": protobufVersion,
+	"snappy_version":   snappyVersion,
+}
+
+var versionInfoTmpl = template.Must(template.New("version").Parse(
+	`prometheus, version {{.version}} ({{.branch}})
+  build user:       {{.user}}
+  build date:       {{.date}}
+  go version:       {{.go_version}}
+  leveldb version:  {{.leveldb_version}}
+  protobuf version: {{.protobuf_version}}
+  snappy version:   {{.snappy_version}}
+`))

main.go

@@ -34,6 +34,7 @@ import (
 var (
 	_ = fmt.Sprintf("")
 
+	printVersion                 = flag.Bool("version", false, "print version information")
 	configFile                   = flag.String("configFile", "prometheus.conf", "Prometheus configuration file name.")
 	metricsStoragePath           = flag.String("metricsStoragePath", "/tmp/metrics", "Base path for metrics storage.")
 	scrapeResultsQueueCapacity   = flag.Int("scrapeResultsQueueCapacity", 4096, "The size of the scrape results queue.")
@@ -45,6 +46,12 @@ var (
 
 func main() {
 	flag.Parse()
+
+	if *printVersion {
+		versionInfoTmpl.Execute(os.Stdout, BuildInfo)
+		os.Exit(0)
+	}
+
 	conf, err := config.LoadFromFile(*configFile)
 	if err != nil {
 		log.Fatalf("Error loading configuration from %s: %v", *configFile, err)