Implement health check for deploy. Make version endpoint to return revision if not set

internal/api/version/version_handler.go

@@ -3,6 +3,7 @@ package version
 import (
 	"io"
 	"net/http"
+	"runtime/debug"
 
 	"go.uber.org/fx"
 
@@ -39,7 +40,20 @@ type handler struct {
 func (h *handler) VersionHandler(w http.ResponseWriter, r *http.Request) {
 	defer r.Body.Close()
 
+	ver := h.version
+	if ver == "unknown" {
+		buildInfo, ok := debug.ReadBuildInfo()
+		if ok {
+			for _, setting := range buildInfo.Settings {
+				if setting.Key == "vcs.revision" {
+					ver = ver + "-" + setting.Value
+					break
+				}
+			}
+		}
+	}
+
 	w.Header().Set("Content-Type", "text/plain")
 	w.WriteHeader(http.StatusOK)
-	io.WriteString(w, h.version)
+	io.WriteString(w, ver+"\n")
 }