Inject and print more version information

cmd/gcr-cleaner-cli/main.go

@@ -104,6 +104,9 @@ func main() {
 }
 
 func realMain(ctx context.Context, logger *gcrcleaner.Logger) error {
+	logger.Debug("cli is starting", "version", version.HumanVersion)
+	defer logger.Debug("cli finished")
+
 	if args := flag.Args(); len(args) > 0 {
 		return fmt.Errorf("expected zero arguments, got %d: %q", len(args), args)
 	}

cmd/gcr-cleaner-server/main.go

@@ -26,6 +26,7 @@ import (
 	"time"
 
 	"github.com/GoogleCloudPlatform/gcr-cleaner/internal/bearerkeychain"
+	"github.com/GoogleCloudPlatform/gcr-cleaner/internal/version"
 	"github.com/GoogleCloudPlatform/gcr-cleaner/pkg/gcrcleaner"
 	gcrauthn "github.com/google/go-containerregistry/pkg/authn"
 	gcrgoogle "github.com/google/go-containerregistry/pkg/v1/google"
@@ -55,6 +56,9 @@ func main() {
 }
 
 func realMain(ctx context.Context, logger *gcrcleaner.Logger) error {
+	logger.Debug("server is starting", "version", version.HumanVersion)
+	defer logger.Debug("server finished")
+
 	port := os.Getenv("PORT")
 	if port == "" {
 		port = "8080"

internal/version/version.go

@@ -1,5 +1,10 @@
 package version
 
+import (
+	"runtime"
+	"runtime/debug"
+)
+
 var (
 	// Name is the name of the binary.
 	Name = "gcr-cleaner"
@@ -10,6 +15,30 @@ var (
 	// Commit is the git sha.
 	Commit = "HEAD"
 
+	// OSArch is the operating system and architecture combination.
+	OSArch = runtime.GOOS + "/" + runtime.GOARCH
+
 	// HumanVersion is the compiled version.
-	HumanVersion = Name + " v" + Version + " (" + Commit + ")"
+	HumanVersion = func() string {
+		version := Version
+		if version == "" {
+			version = "source"
+		}
+
+		commit := Commit
+		if commit == "" {
+			if info, ok := debug.ReadBuildInfo(); ok {
+				for _, setting := range info.Settings {
+					if setting.Key == "vcs.revision" {
+						return setting.Value
+					}
+				}
+			}
+		}
+		if commit == "" {
+			commit = "unknown"
+		}
+
+		return Name + " " + version + " (" + commit + ", " + OSArch + ")"
+	}()
 )