Read Go build info from the binary

Author: lucacome

.goreleaser.yml

@@ -14,6 +14,8 @@ builds:
       - all=-trimpath={{.Env.GOPATH}}
     asmflags:
       - all=-trimpath={{.Env.GOPATH}}
+    ldflags:
+      - -s -w -X main.version={{.Version}}
     main: ./cmd/gateway/
     binary: gateway
 

Makefile

@@ -10,7 +10,7 @@ TARGET ?= local ## The target of the build. Possible values: local and container
 KIND_KUBE_CONFIG_FOLDER = $${HOME}/.kube/kind ## The folder where the kind kubeconfig is stored
 OUT_DIR ?= $(shell pwd)/build/out ## The folder where the binary will be stored
 ARCH ?= amd64 ## The architecture of the image and/or binary. For example: amd64 or arm64
-override DOCKER_BUILD_OPTIONS += --build-arg VERSION=$(VERSION) --build-arg GIT_COMMIT=$(GIT_COMMIT) --build-arg DATE=$(DATE) ## The options for the docker build command. For example, --pull
+override DOCKER_BUILD_OPTIONS += --build-arg VERSION=$(VERSION) ## The options for the docker build command. For example, --pull
 
 .DEFAULT_GOAL := help
 
@@ -28,7 +28,7 @@ container: build ## Build the container
 build: ## Build the binary
 ifeq (${TARGET},local)
 	@go version || (code=$$?; printf "\033[0;31mError\033[0m: unable to build locally\n"; exit $$code)
-	CGO_ENABLED=0 GOOS=linux GOARCH=$(ARCH) go build -trimpath -a -ldflags "-s -w -X main.version=${VERSION} -X main.commit=${GIT_COMMIT} -X main.date=${DATE}" -o $(OUT_DIR)/gateway github.com/nginxinc/nginx-kubernetes-gateway/cmd/gateway
+	CGO_ENABLED=0 GOOS=linux GOARCH=$(ARCH) go build -trimpath -a -ldflags "-s -w -X main.version=${VERSION}" -o $(OUT_DIR)/gateway github.com/nginxinc/nginx-kubernetes-gateway/cmd/gateway
 endif
 
 .PHONY: build-goreleaser

build/Dockerfile

@@ -1,8 +1,6 @@
 # syntax=docker/dockerfile:1.4
 FROM golang:1.20 as builder
 ARG VERSION
-ARG GIT_COMMIT
-ARG DATE
 
 WORKDIR /go/src/github.com/nginxinc/nginx-kubernetes-gateway/cmd/gateway
 
@@ -12,7 +10,7 @@ RUN go mod download
 COPY cmd /go/src/github.com/nginxinc/nginx-kubernetes-gateway/cmd
 COPY internal /go/src/github.com/nginxinc/nginx-kubernetes-gateway/internal
 COPY pkg /go/src/github.com/nginxinc/nginx-kubernetes-gateway/pkg
-RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -a -ldflags "-s -w -X main.version=${VERSION} -X main.commit=${GIT_COMMIT} -X main.date=${DATE}" -o gateway .
+RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -a -ldflags "-s -w -X main.version=${VERSION}" -o gateway .
 
 FROM alpine:3.18 as capabilizer
 RUN apk add --no-cache libcap

cmd/gateway/commands.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"os"
+	"runtime/debug"
 
 	"github.com/spf13/cobra"
 	"k8s.io/apimachinery/pkg/types"
@@ -124,10 +125,12 @@ func createStaticModeCommand() *cobra.Command {
 		Short: "Configure NGINX in the scope of a single Gateway resource",
 		RunE: func(cmd *cobra.Command, args []string) error {
 			logger := zap.New()
+			commit, date, dirty := getBuildInfo()
 			logger.Info("Starting NGINX Kubernetes Gateway in static mode",
 				"version", version,
 				"commit", commit,
 				"date", date,
+				"dirty", dirty,
 			)
 
 			podIP := os.Getenv("POD_IP")
@@ -184,10 +187,12 @@ func createProvisionerModeCommand() *cobra.Command {
 		Hidden: true,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			logger := zap.New()
+			commit, date, dirty := getBuildInfo()
 			logger.Info("Starting NGINX Kubernetes Gateway Provisioner",
 				"version", version,
 				"commit", commit,
 				"date", date,
+				"dirty", dirty,
 			)
 
 			return provisioner.StartManager(provisioner.Config{
@@ -198,3 +203,26 @@ func createProvisionerModeCommand() *cobra.Command {
 		},
 	}
 }
+
+func getBuildInfo() (commitHash string, commitTime string, dirtyBuild bool) {
+	commitHash = "unknown"
+	commitTime = "unknown"
+	dirtyBuild = true
+
+	info, ok := debug.ReadBuildInfo()
+	if !ok {
+		return
+	}
+	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
+}

cmd/gateway/main.go

@@ -5,12 +5,8 @@ import (
 	"os"
 )
 
-var (
-	// Set during go build
-	version string
-	commit  string
-	date    string
-)
+// Set during go build
+var version string
 
 func main() {
 	rootCmd := createRootCommand()