feat: binaries know their build date and commit hash

Will be used for a future metric reporting exporter infos.

Dockerfile

@@ -19,8 +19,11 @@ ENV GOOS=${TARGETOS}
 ENV GOARCH=${TARGETARCH}
 
 ARG VERSION="0.0.0"
-
-RUN go build -tags netgo,osusergo -ldflags "-X \"github.com/enix/x509-certificate-exporter/v3/internal.Version=${VERSION}\"" ./cmd/x509-certificate-exporter
+  -tags netgo,osusergo \
+  -ldflags "-X \"github.com/enix/x509-certificate-exporter/v3/internal.Version=${VERSION}\" \
+            -X \"github.com/enix/x509-certificate-exporter/v3/internal.CommitHash=${VCS_REF}\" \
+            -X \"github.com/enix/x509-certificate-exporter/v3/internal.BuildDateTime=$(date -u -Iseconds)\"" \
+  ./cmd/x509-certificate-exporter
 
 
 ## Production Stage

cmd/x509-certificate-exporter/main.go

@@ -109,7 +109,7 @@ func main() {
 		}
 	}
 
-	log.Infof("starting %s version %s", path.Base(os.Args[0]), internal.Version)
+	log.Infof("starting %s version %s (%s) (%s)", path.Base(os.Args[0]), internal.Version, internal.CommitHash, internal.BuildDateTime)
 	rand.Seed(time.Now().UnixNano())
 	exporter.ListenAndServe()
 }

internal/version.go

@@ -1,4 +1,6 @@
 package internal
 
-// Version is the exporter semantic version and is set at link time
+// Version and build informations set at link time
 var Version = "0.0.0"
+var CommitHash = ""
+var BuildDateTime = ""