feat: add health check with /heatlhz endpoint (#197)

pkg/influx/api.go

@@ -29,6 +29,7 @@ func (a *API) Register(router *mux.Router) {
 	// Registering two write endpoints; the second is necessary to allow for compatibility with clients that hard-code the endpoint
 	registerer.RegisterRoute("/api/v1/push/influx/write", http.HandlerFunc(a.handleSeriesPush), http.MethodPost)
 	registerer.RegisterRoute("/api/v2/write", http.HandlerFunc(a.handleSeriesPush), http.MethodPost)
+	registerer.RegisterRoute("/healthz", http.HandlerFunc(a.handleHealth), http.MethodGet)
 }
 
 func NewAPI(conf ProxyConfig, client remotewrite.Client, recorder Recorder) (*API, error) {
@@ -40,6 +41,22 @@ func NewAPI(conf ProxyConfig, client remotewrite.Client, recorder Recorder) (*AP
 	}, nil
 }
 
+func (a *API) handleHealth(w http.ResponseWriter, r *http.Request) {
+	span, _ := opentracing.StartSpanFromContext(r.Context(), "handleHealth")
+	defer span.Finish()
+
+	logger := withRequestInfo(a.logger, r)
+	_, err := w.Write([]byte("OK"))
+
+	if err != nil {
+		ext.LogError(span, err)
+		a.handleError(w, r, err, logger)
+		return
+	}
+
+	w.WriteHeader(http.StatusOK)
+}
+
 // HandlerForInfluxLine is a http.Handler which accepts Influx Line protocol and converts it to WriteRequests.
 func (a *API) handleSeriesPush(w http.ResponseWriter, r *http.Request) {
 	span, ctx := opentracing.StartSpanFromContext(r.Context(), "handleSeriesPush")

pkg/influx/api_test.go

@@ -219,3 +219,17 @@ func TestHandleSeriesPush(t *testing.T) {
 		})
 	}
 }
+func TestHandleHealth(t *testing.T) {
+	req := httptest.NewRequest("GET", "/healthz", nil)
+	req.Header.Set("X-Scope-OrgID", "fake")
+	rec := httptest.NewRecorder()
+	logger := log.NewNopLogger()
+	api := &API{
+		logger: logger,
+	}
+
+	api.handleHealth(rec, req)
+
+	assert.Equal(t, http.StatusOK, rec.Code)
+	assert.Equal(t, "OK", rec.Body.String())
+}