From 3ed9f1d5a9e392dfe52abd93e9cb287b1a61b4e2 Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Mon, 2 Nov 2020 01:09:37 +0200
Subject: [PATCH] lib/promscrape: properly handle response body after 301
 redirect

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/869
---
 CHANGELOG.md             | 1 +
 lib/promscrape/client.go | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 29cae90ff1..86a9fa17a6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@
 * BUGFIX: vmagent: add leading missing slash to metrics path like Prometheus does. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/835
 * BUGFIX: vmagent: drop packet if remote storage returns 4xx status code. This make the behaviour consistent with Prometheus.
   See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/873
+* BUGFIX: vmagent: properly handle 301 redirects. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/869
 
 
 # [v1.44.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.44.0)
diff --git a/lib/promscrape/client.go b/lib/promscrape/client.go
index 9504f9f030..b7a93ffbd6 100644
--- a/lib/promscrape/client.go
+++ b/lib/promscrape/client.go
@@ -169,9 +169,6 @@ func (c *client) ReadData(dst []byte) ([]byte, error) {
 		dst = resp.SwapBody(dst)
 	}
 	err := doRequestWithPossibleRetry(c.hc, req, resp, deadline)
-	if swapResponseBodies {
-		dst = resp.SwapBody(dst)
-	}
 	statusCode := resp.StatusCode()
 	if err == nil && (statusCode == fasthttp.StatusMovedPermanently || statusCode == fasthttp.StatusFound) {
 		// Allow a single redirect.
@@ -183,6 +180,9 @@ func (c *client) ReadData(dst []byte) ([]byte, error) {
 			statusCode = resp.StatusCode()
 		}
 	}
+	if swapResponseBodies {
+		dst = resp.SwapBody(dst)
+	}
 	fasthttp.ReleaseRequest(req)
 	if err != nil {
 		fasthttp.ReleaseResponse(resp)