From 2eadf30358ca34f9ece4b76c64d3b76d8c116e45 Mon Sep 17 00:00:00 2001
From: Markus Lehtonen <markus.lehtonen@intel.com>
Date: Thu, 30 Jun 2022 10:08:51 +0300
Subject: [PATCH] test/e2e: fix GetCurrentKubeletConfig

Seemingly on slow connections if the response to /configz request was
chunked the kubectl proxy was terminated before the response body was
received and read, causing unexpected EOF errors. This patch changes the
configz polling code so that the whole response body is read before
closing the proxy connection.
---
 test/e2e/framework/kubelet/config.go | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/test/e2e/framework/kubelet/config.go b/test/e2e/framework/kubelet/config.go
index 8e481da415a..b0eccf97ddc 100644
--- a/test/e2e/framework/kubelet/config.go
+++ b/test/e2e/framework/kubelet/config.go
@@ -38,7 +38,7 @@ import (
 // GetCurrentKubeletConfig fetches the current Kubelet Config for the given node
 func GetCurrentKubeletConfig(nodeName, namespace string, useProxy bool) (*kubeletconfig.KubeletConfiguration, error) {
 	resp := pollConfigz(5*time.Minute, 5*time.Second, nodeName, namespace, useProxy)
-	if resp == nil {
+	if len(resp) == 0 {
 		return nil, fmt.Errorf("failed to fetch /configz from %q", nodeName)
 	}
 	kubeCfg, err := decodeConfigz(resp)
@@ -49,7 +49,7 @@ func GetCurrentKubeletConfig(nodeName, namespace string, useProxy bool) (*kubele
 }
 
 // returns a status 200 response from the /configz endpoint or nil if fails
-func pollConfigz(timeout time.Duration, pollInterval time.Duration, nodeName, namespace string, useProxy bool) *http.Response {
+func pollConfigz(timeout time.Duration, pollInterval time.Duration, nodeName, namespace string, useProxy bool) []byte {
 	endpoint := ""
 	if useProxy {
 		// start local proxy, so we can send graceful deletion over query string, rather than body parameter
@@ -88,26 +88,35 @@ func pollConfigz(timeout time.Duration, pollInterval time.Duration, nodeName, na
 	}
 	req.Header.Add("Accept", "application/json")
 
-	var resp *http.Response
+	var respBody []byte
 	err = wait.PollImmediate(pollInterval, timeout, func() (bool, error) {
-		resp, err = client.Do(req)
+		resp, err := client.Do(req)
 		if err != nil {
 			framework.Logf("Failed to get /configz, retrying. Error: %v", err)
 			return false, nil
 		}
+		defer resp.Body.Close()
+
 		if resp.StatusCode != 200 {
 			framework.Logf("/configz response status not 200, retrying. Response was: %+v", resp)
 			return false, nil
 		}
 
+		respBody, err = io.ReadAll(resp.Body)
+		if err != nil {
+			framework.Logf("failed to read body from /configz response, retrying. Error: %v", err)
+			return false, nil
+		}
+
 		return true, nil
 	})
 	framework.ExpectNoError(err, "Failed to get successful response from /configz")
-	return resp
+
+	return respBody
 }
 
 // Decodes the http response from /configz and returns a kubeletconfig.KubeletConfiguration (internal type).
-func decodeConfigz(resp *http.Response) (*kubeletconfig.KubeletConfiguration, error) {
+func decodeConfigz(respBody []byte) (*kubeletconfig.KubeletConfiguration, error) {
 	// This hack because /configz reports the following structure:
 	// {"kubeletconfig": {the JSON representation of kubeletconfigv1beta1.KubeletConfiguration}}
 	type configzWrapper struct {
@@ -117,12 +126,7 @@ func decodeConfigz(resp *http.Response) (*kubeletconfig.KubeletConfiguration, er
 	configz := configzWrapper{}
 	kubeCfg := kubeletconfig.KubeletConfiguration{}
 
-	contentsBytes, err := io.ReadAll(resp.Body)
-	if err != nil {
-		return nil, err
-	}
-
-	err = json.Unmarshal(contentsBytes, &configz)
+	err := json.Unmarshal(respBody, &configz)
 	if err != nil {
 		return nil, err
 	}