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
This change refactors the way Kubelet's DockerPuller handles the docker config credentials to utilize a new credentialprovider library.
The credentialprovider library is based on several of the files from the Kubelet's dockertools directory, but supports a new pluggable model for retrieving a .dockercfg-compatible JSON blob with credentials.
With this change, the Kubelet will lazily ask for the docker config from a set of DockerConfigProvider extensions each time it needs a credential.
This change provides common implementations of DockerConfigProvider for:
- "Default": load .dockercfg from disk
- "Caching": wraps another provider in a cache that expires after a pre-specified lifetime.
GCP-only:
- "google-dockercfg": reads a .dockercfg from a GCE instance's metadata
- "google-dockercfg-url": reads a .dockercfg from a URL specified in a GCE instance's metadata.
- "google-container-registry": reads an access token from GCE metadata into a password field.
Daniel Smith