app/vmagent/remotewrite: add missing resp.Body.Close() after pushin…

…g data to remote storage

Missing body close could disable HTTP keep-alive connections.

Updates #653

app/vmagent/remotewrite/client.go

@@ -220,28 +220,33 @@ again:
 		goto again
 	}
 	statusCode := resp.StatusCode
-	if statusCode/100 != 2 {
-		metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_requests_total{url=%q, status_code="%d"}`, c.urlLabelValue, statusCode)).Inc()
-		retryDuration *= 2
-		if retryDuration > time.Minute {
-			retryDuration = time.Minute
-		}
-		body, err := ioutil.ReadAll(resp.Body)
-		if err != nil {
-			logger.Errorf("cannot read response body from %q: %s", c.remoteWriteURL, err)
-		} else {
-			logger.Errorf("unexpected status code received after sending a block with size %d bytes to %q: %d; response body=%q; re-sending the block in %.3f seconds",
-				len(block), c.remoteWriteURL, statusCode, body, retryDuration.Seconds())
-		}
-		t := time.NewTimer(retryDuration)
-		select {
-		case <-c.stopCh:
-			t.Stop()
-			return
-		case <-t.C:
-		}
-		c.retriesCount.Inc()
-		goto again
+	if statusCode/100 == 2 {
+		_ = resp.Body.Close()
+		c.requestsOKCount.Inc()
+		return
+	}
+
+	// Unexpected status code returned
+	metrics.GetOrCreateCounter(fmt.Sprintf(`vmagent_remotewrite_requests_total{url=%q, status_code="%d"}`, c.urlLabelValue, statusCode)).Inc()
+	retryDuration *= 2
+	if retryDuration > time.Minute {
+		retryDuration = time.Minute
+	}
+	body, err := ioutil.ReadAll(resp.Body)
+	_ = resp.Body.Close()
+	if err != nil {
+		logger.Errorf("cannot read response body from %q: %s", c.remoteWriteURL, err)
+	} else {
+		logger.Errorf("unexpected status code received after sending a block with size %d bytes to %q: %d; response body=%q; re-sending the block in %.3f seconds",
+			len(block), c.remoteWriteURL, statusCode, body, retryDuration.Seconds())
+	}
+	t := time.NewTimer(retryDuration)
+	select {
+	case <-c.stopCh:
+		t.Stop()
+		return
+	case <-t.C:
 	}
-	c.requestsOKCount.Inc()
+	c.retriesCount.Inc()
+	goto again
 }