feat(client): add ping method to http/s sender

http_sender.go

@@ -155,13 +155,15 @@ func newHttpLineSender(conf *lineSenderConfig) (*httpLineSender, error) {
 		s.globalTransport.RegisterClient()
 	}
 
-	s.uri = "http"
+	var protocol = "http"
 	if conf.tlsMode != tlsDisabled {
-		s.uri += "s"
+		protocol += "s"
 	}
-	s.uri += fmt.Sprintf("://%s/write", s.address)
 
-	return s, nil
+	s.uri = fmt.Sprintf("%s://%s/write", protocol, s.address)
+
+	var pingUri = fmt.Sprintf("%s://%s/ping", protocol, s.address)
+	return s, s.ping(pingUri)
 }
 
 func (s *httpLineSender) Flush(ctx context.Context) error {
@@ -336,23 +338,56 @@ func (s *httpLineSender) At(ctx context.Context, ts time.Time) error {
 	return nil
 }
 
-// makeRequest returns a boolean if we need to retry the request
-func (s *httpLineSender) makeRequest(ctx context.Context) (bool, error) {
+func (s *httpLineSender) ping(uri string) error {
+	buf := bytes.Buffer{}
+	success := http.StatusNoContent
+
 	req, err := http.NewRequest(
 		http.MethodPost,
-		s.uri,
-		bytes.NewReader(s.buf.Bytes()),
+		uri,
+		&buf,
 	)
 	if err != nil {
-		return false, err
+		return err
 	}
-	req.ContentLength = int64(s.BufLen())
 
+	s.setAuth(req)
+
+	resp, err := s.client.Do(req)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != success {
+		return fmt.Errorf("ping returned status %d, expected %d", resp.StatusCode, success)
+	}
+
+	return nil
+
+}
+
+func (s *httpLineSender) setAuth(req *http.Request) {
 	if s.user != "" && s.pass != "" {
 		req.SetBasicAuth(s.user, s.pass)
 	} else if s.token != "" {
 		req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", s.token))
 	}
+}
+
+// makeRequest returns a boolean if we need to retry the request
+func (s *httpLineSender) makeRequest(ctx context.Context) (bool, error) {
+	req, err := http.NewRequest(
+		http.MethodPost,
+		s.uri,
+		bytes.NewReader(s.buf.Bytes()),
+	)
+	if err != nil {
+		return false, err
+	}
+
+	s.setAuth(req)
+
+	req.ContentLength = int64(s.BufLen())
 
 	// reqTimeout = ( request.len() / request_min_throughput ) + request_timeout
 	// nb: conversion from int to time.Duration is in milliseconds

http_sender_test.go

@@ -93,19 +93,19 @@ func TestHttpHappyCasesFromConf(t *testing.T) {
 }
 
 func TestHttpHappyCasesFromEnv(t *testing.T) {
-	var (
-		addr = "localhost:1111"
-	)
+	// Set up test server to handle pings from constructor
+	s, err := newTestServerWithProtocol(readAndDiscard, "http")
+	assert.NoError(t, err)
 
 	testCases := []httpConfigTestCase{
 		{
 			name:   "addr only",
-			config: fmt.Sprintf("http::addr=%s", addr),
+			config: fmt.Sprintf("http::addr=%s", s.addr),
 		},
 		{
 			name: "auto flush",
 			config: fmt.Sprintf("http::addr=%s;auto_flush_rows=100;auto_flush_interval=1000;",
-				addr),
+				s.addr),
 		},
 	}
 

tcp_sender_test.go

@@ -300,7 +300,6 @@ func TestErrorOnContextDeadline(t *testing.T) {
 	}
 	t.Fail()
 }
-
 func BenchmarkLineSenderBatch1000(b *testing.B) {
 	ctx := context.Background()
 

utils_test.go

@@ -194,6 +194,12 @@ func (s *testServer) serveHttp() {
 			err error
 		)
 
+		// handle ping
+		if r.URL.Path == "/ping" {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+
 		switch s.serverType {
 		case failFirstThenSendToBackChannel:
 			if atomic.AddInt64(&reqs, 1) == 1 {