Read Go build info from the binary (#276)

Author: lucacome

.github/workflows/ci.yml

@@ -140,4 +140,3 @@ jobs:
           cache-to: type=gha,mode=max
           build-args: |
             VERSION=${{ steps.meta.outputs.version }}
-            GIT_COMMIT=${{ github.sha }}

Makefile

@@ -2,17 +2,9 @@ VERSION = 0.10.0
 TAG = $(VERSION)
 PREFIX = nginx/nginx-prometheus-exporter
 
-DOCKERFILEPATH = build
-DOCKERFILE = Dockerfile
-
-GIT_COMMIT = $(shell git rev-parse HEAD)
-DATE = $(shell date -u +"%Y-%m-%dT%H:%M:%SZ")
-
-export DOCKER_BUILDKIT = 1
-
 .PHONY: nginx-prometheus-exporter
 nginx-prometheus-exporter:
-	CGO_ENABLED=0 go build -trimpath -ldflags "-s -w -X main.version=$(VERSION) -X main.commit=$(GIT_COMMIT) -X main.date=$(DATE)" -o nginx-prometheus-exporter
+	CGO_ENABLED=0 go build -trimpath -ldflags "-s -w -X main.version=$(VERSION)" -o nginx-prometheus-exporter
 
 .PHONY: build-goreleaser
 build-goreleaser: ## Build all binaries using GoReleaser
@@ -29,7 +21,7 @@ test:
 
 .PHONY: container
 container:
-	docker build --build-arg VERSION=$(VERSION) --build-arg GIT_COMMIT=$(GIT_COMMIT) --build-arg DATE=$(DATE) --target container -f $(DOCKERFILEPATH)/$(DOCKERFILE) -t $(PREFIX):$(TAG) .
+	docker build --build-arg VERSION=$(VERSION) --target container -f build/Dockerfile -t $(PREFIX):$(TAG) .
 
 .PHONY: push
 push: container

build/Dockerfile

@@ -1,8 +1,6 @@
 # syntax=docker/dockerfile:1.4
 FROM golang:1.18 as base
 ARG VERSION
-ARG GIT_COMMIT
-ARG DATE
 ARG TARGETARCH
 
 WORKDIR /go/src/github.com/nginxinc/nginx-prometheus-exporter
@@ -13,7 +11,7 @@ RUN go mod download
 COPY --link *.go ./
 COPY --link collector ./collector
 COPY --link client ./client
-RUN CGO_ENABLED=0 GOOS=linux GOARCH=$TARGETARCH go build -trimpath -a -ldflags "-s -w -X main.version=${VERSION} -X main.commit=${GIT_COMMIT} -X main.date=${DATE}" -o nginx-prometheus-exporter .
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=$TARGETARCH go build -trimpath -a -ldflags "-s -w -X main.version=${VERSION}" -o nginx-prometheus-exporter .
 
 
 FROM scratch as intermediate

exporter.go

@@ -11,6 +11,8 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"runtime"
+	"runtime/debug"
 	"strconv"
 	"strings"
 	"syscall"
@@ -218,8 +220,6 @@ func getListener(listenAddress string) (net.Listener, error) {
 var (
 	// Set during go build
 	version string
-	commit  string
-	date    string
 
 	// Defaults values
 	defaultListenAddress      = getEnv("LISTEN_ADDRESS", ":9113")
@@ -297,12 +297,16 @@ For NGINX, the stub_status page must be available through the URI. For NGINX Plu
 func main() {
 	flag.Parse()
 
+	commitHash, commitTime, dirtyBuild := getBuildInfo()
+	arch := fmt.Sprintf("%v/%v", runtime.GOOS, runtime.GOARCH)
+
+	fmt.Printf("NGINX Prometheus Exporter version=%v commit=%v date=%v, dirty=%v, arch=%v, go=%v\n", version, commitHash, commitTime, dirtyBuild, arch, runtime.Version())
+
 	if *displayVersion {
-		fmt.Printf("NGINX Prometheus Exporter version=%v commit=%v date=%v\n", version, commit, date)
 		os.Exit(0)
 	}
 
-	log.Printf("Starting NGINX Prometheus Exporter version=%v commit=%v date=%v", version, commit, date)
+	log.Printf("Starting...")
 
 	registry := prometheus.NewRegistry()
 
@@ -314,8 +318,11 @@ func main() {
 				constLabels.labels,
 				prometheus.Labels{
 					"version": version,
-					"commit":  commit,
-					"date":    date,
+					"commit":  commitHash,
+					"date":    commitTime,
+					"dirty":   strconv.FormatBool(dirtyBuild),
+					"arch":    arch,
+					"go":      runtime.Version(),
 				},
 			),
 		},
@@ -464,3 +471,23 @@ func cloneRequest(req *http.Request) *http.Request {
 	}
 	return r
 }
+
+func getBuildInfo() (string, string, bool) {
+	var commitHash, commitTime string
+	var dirtyBuild bool
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return "", "", false
+	}
+	for _, kv := range info.Settings {
+		switch kv.Key {
+		case "vcs.revision":
+			commitHash = kv.Value
+		case "vcs.time":
+			commitTime = kv.Value
+		case "vcs.modified":
+			dirtyBuild = kv.Value == "true"
+		}
+	}
+	return commitHash, commitTime, dirtyBuild
+}