From 65c246d45a41552d6bf20b273dbd76942728f102 Mon Sep 17 00:00:00 2001
From: Matt Moore <mattmoor@google.com>
Date: Sun, 30 Nov 2014 16:31:03 -0800
Subject: [PATCH] Make credentialprovider less verbose about benign errors.

In particular, a few of the utilities used within the credentialprovider had the pattern:
   glog.Errorf("while blah %s: %v", s, err)
   return nil, err

This change propagates those error message and puts the burden of logging on the caller.

In particular, this allows us to squelch all output during kubelet startup when we are detecting whether certain credentialprovider plugins should even be enabled.

Fixes: https://github.com/GoogleCloudPlatform/kubernetes/issues/2673
---
 pkg/credentialprovider/config.go       | 22 ++++++++++++++++------
 pkg/credentialprovider/gcp/metadata.go | 14 +++++++++++---
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/pkg/credentialprovider/config.go b/pkg/credentialprovider/config.go
index b54ff7f083f..03999093f7e 100644
--- a/pkg/credentialprovider/config.go
+++ b/pkg/credentialprovider/config.go
@@ -65,10 +65,21 @@ func ReadDockerConfigFile() (cfg DockerConfig, err error) {
 	return readDockerConfigFileFromBytes(contents)
 }
 
+// HttpError wraps a non-StatusOK error code as an error.
+type HttpError struct {
+	StatusCode int
+	Url        string
+}
+
+// Error implements error
+func (he *HttpError) Error() string {
+	return fmt.Sprintf("http status code: %d while fetching url %s",
+		he.StatusCode, he.Url)
+}
+
 func ReadUrl(url string, client *http.Client, header *http.Header) (body []byte, err error) {
 	req, err := http.NewRequest("GET", url, nil)
 	if err != nil {
-		glog.Errorf("while creating request to read %s: %v", url, err)
 		return nil, err
 	}
 	if header != nil {
@@ -76,21 +87,20 @@ func ReadUrl(url string, client *http.Client, header *http.Header) (body []byte,
 	}
 	resp, err := client.Do(req)
 	if err != nil {
-		glog.Errorf("while trying to read %s: %v", url, err)
 		return nil, err
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		err := fmt.Errorf("http status code: %d while fetching url %s", resp.StatusCode, url)
-		glog.Errorf("while trying to read %s: %v", url, err)
 		glog.V(2).Infof("body of failing http response: %v", resp.Body)
-		return nil, err
+		return nil, &HttpError{
+			StatusCode: resp.StatusCode,
+			Url:        url,
+		}
 	}
 
 	contents, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		glog.Errorf("while trying to read %s: %v", url, err)
 		return nil, err
 	}
 
diff --git a/pkg/credentialprovider/gcp/metadata.go b/pkg/credentialprovider/gcp/metadata.go
index dd7149c42a9..c005f0ac5b7 100644
--- a/pkg/credentialprovider/gcp/metadata.go
+++ b/pkg/credentialprovider/gcp/metadata.go
@@ -105,7 +105,9 @@ func (g *metadataProvider) Enabled() bool {
 func (g *dockerConfigKeyProvider) Provide() credentialprovider.DockerConfig {
 	// Read the contents of the google-dockercfg metadata key and
 	// parse them as an alternate .dockercfg
-	if cfg, err := credentialprovider.ReadDockerConfigFileFromUrl(dockerConfigKey, g.Client, metadataHeader); err == nil {
+	if cfg, err := credentialprovider.ReadDockerConfigFileFromUrl(dockerConfigKey, g.Client, metadataHeader); err != nil {
+		glog.Errorf("while reading 'google-dockercfg' metadata: %v", err)
+	} else {
 		return cfg
 	}
 
@@ -115,9 +117,13 @@ func (g *dockerConfigKeyProvider) Provide() credentialprovider.DockerConfig {
 // Provide implements DockerConfigProvider
 func (g *dockerConfigUrlKeyProvider) Provide() credentialprovider.DockerConfig {
 	// Read the contents of the google-dockercfg-url key and load a .dockercfg from there
-	if url, err := credentialprovider.ReadUrl(dockerConfigUrlKey, g.Client, metadataHeader); err == nil {
+	if url, err := credentialprovider.ReadUrl(dockerConfigUrlKey, g.Client, metadataHeader); err != nil {
+		glog.Errorf("while reading 'google-dockercfg-url' metadata: %v", err)
+	} else {
 		if strings.HasPrefix(string(url), "http") {
-			if cfg, err := credentialprovider.ReadDockerConfigFileFromUrl(string(url), g.Client, nil); err == nil {
+			if cfg, err := credentialprovider.ReadDockerConfigFileFromUrl(string(url), g.Client, nil); err != nil {
+				glog.Errorf("while reading 'google-dockercfg-url'-specified url: %s, %v", string(url), err)
+			} else {
 				return cfg
 			}
 		} else {
@@ -162,11 +168,13 @@ func (g *containerRegistryProvider) Provide() credentialprovider.DockerConfig {
 
 	tokenJsonBlob, err := credentialprovider.ReadUrl(metadataToken, g.Client, metadataHeader)
 	if err != nil {
+		glog.Errorf("while reading access token endpoint: %v", err)
 		return cfg
 	}
 
 	email, err := credentialprovider.ReadUrl(metadataEmail, g.Client, metadataHeader)
 	if err != nil {
+		glog.Errorf("while reading email endpoint: %v", err)
 		return cfg
 	}