From 7db18f27a426ceefba935d1eb5498bf896c1df1e Mon Sep 17 00:00:00 2001
From: Kevin Labesse <kevin@labesse.me>
Date: Wed, 16 Sep 2020 09:45:36 +0200
Subject: [PATCH] ready route

---
 .../influxdb_v2_listener.go                   | 18 ++++++++++++++++
 .../influxdb_v2_listener_test.go              | 21 +++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/plugins/inputs/influxdb_v2_listener/influxdb_v2_listener.go b/plugins/inputs/influxdb_v2_listener/influxdb_v2_listener.go
index bd6eb5405100c..01d47b201f502 100644
--- a/plugins/inputs/influxdb_v2_listener/influxdb_v2_listener.go
+++ b/plugins/inputs/influxdb_v2_listener/influxdb_v2_listener.go
@@ -53,6 +53,7 @@ type InfluxDBV2Listener struct {
 	bytesRecv       selfstat.Stat
 	requestsServed  selfstat.Stat
 	writesServed    selfstat.Stat
+	readysServed    selfstat.Stat
 	requestsRecv    selfstat.Stat
 	notFoundsServed selfstat.Stat
 	authFailures    selfstat.Stat
@@ -115,6 +116,7 @@ func (h *InfluxDBV2Listener) routes() {
 	)
 
 	h.mux.Handle("/api/v2/write", authHandler(h.handleWrite()))
+	h.mux.Handle("/api/v2/ready", h.handleReady())
 	h.mux.Handle("/", authHandler(h.handleDefault()))
 }
 
@@ -125,6 +127,7 @@ func (h *InfluxDBV2Listener) Init() error {
 	h.bytesRecv = selfstat.Register("influxdb_v2_listener", "bytes_received", tags)
 	h.requestsServed = selfstat.Register("influxdb_v2_listener", "requests_served", tags)
 	h.writesServed = selfstat.Register("influxdb_v2_listener", "writes_served", tags)
+	h.readysServed = selfstat.Register("influxdb_v2_listener", "readys_served", tags)
 	h.requestsRecv = selfstat.Register("influxdb_v2_listener", "requests_received", tags)
 	h.notFoundsServed = selfstat.Register("influxdb_v2_listener", "not_founds_served", tags)
 	h.authFailures = selfstat.Register("influxdb_v2_listener", "auth_failures", tags)
@@ -195,6 +198,21 @@ func (h *InfluxDBV2Listener) ServeHTTP(res http.ResponseWriter, req *http.Reques
 	h.requestsServed.Incr(1)
 }
 
+func (h *InfluxDBV2Listener) handleReady() http.HandlerFunc {
+	return func(res http.ResponseWriter, req *http.Request) {
+		defer h.readysServed.Incr(1)
+
+		// respond to ready requests
+		res.Header().Set("Content-Type", "application/json")
+		res.WriteHeader(http.StatusOK)
+		b, _ := json.Marshal(map[string]string{
+			"started": h.startTime.Format(time.RFC3339Nano),
+			"status":  "ready",
+			"up":      h.timeFunc().Sub(h.startTime).String()})
+		res.Write(b)
+	}
+}
+
 func (h *InfluxDBV2Listener) handleDefault() http.HandlerFunc {
 	return func(res http.ResponseWriter, req *http.Request) {
 		defer h.notFoundsServed.Incr(1)
diff --git a/plugins/inputs/influxdb_v2_listener/influxdb_v2_listener_test.go b/plugins/inputs/influxdb_v2_listener/influxdb_v2_listener_test.go
index 0cdb9650cca50..2a80bb4d351e6 100644
--- a/plugins/inputs/influxdb_v2_listener/influxdb_v2_listener_test.go
+++ b/plugins/inputs/influxdb_v2_listener/influxdb_v2_listener_test.go
@@ -465,6 +465,27 @@ func TestWriteEmpty(t *testing.T) {
 	require.EqualValues(t, 204, resp.StatusCode)
 }
 
+func TestReady(t *testing.T) {
+	listener := newTestListener()
+	listener.timeFunc = func() time.Time {
+		return time.Unix(42, 123456789)
+	}
+	acc := &testutil.Accumulator{}
+	require.NoError(t, listener.Init())
+	require.NoError(t, listener.Start(acc))
+	defer listener.Stop()
+
+	// post ping to listener
+	resp, err := http.Get(createURL(listener, "http", "/api/v2/ready", ""))
+	require.NoError(t, err)
+	require.Equal(t, "application/json", resp.Header["Content-Type"][0])
+	bodyBytes, err := ioutil.ReadAll(resp.Body)
+	require.NoError(t, err)
+	require.Contains(t, string(bodyBytes), "\"status\":\"ready\"")
+	resp.Body.Close()
+	require.EqualValues(t, 200, resp.StatusCode)
+}
+
 func TestWriteWithPrecision(t *testing.T) {
 	listener := newTestListener()