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credential_provider.md

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Credential Provider

This feature is in alpha in 1.20 until 1.23 and shouldn't be used in production environments. The KubeletCredentialProviders feature gate needs to be enabled to use this functionality. Starting in Kubernetes 1.24, the credential provider feature has moved to beta.

As part of the cloud provider extraction, KEP-2133 proposed an extensible way to fetch credentials for pulling images. When kubelet needs credentials to fetch an image, it will now invoke a plugin based on the configuration provided by the cluster operator. Please see the original KEP for details.

We currently have the implementation for fetching ECR credentials. In order to use this new plugin, you'll have to:

  • Pass the folder where the binary is located as --image-credential-provider-bin-dir to the kubelet.
  • Create a new CredentialProviderConfig and pass its location to the kubelet via --image-credential-provider-config.

Example config:

{
    "providers": [
        {
            "name": "ecr-credential-provider",
            "matchImages" : [
                "*.dkr.ecr.*.amazonaws.com",
                "*.dkr.ecr.*.amazonaws.com.cn",
            ],
            "apiVersion": "credentialprovider.kubelet.k8s.io/v1",
            "defaultCacheDuration": "0"
        }
    ]
}

Once you pass this config to the kubelet, every time it needs to fetch an image that matches one of the "matchImages" patterns, it will invoke the "ecr-credential-provider" binary in the --image-credential-provider-bin-dir folder. In turn, the plugin will fetch the credentials for kubelet and send it back via stdio. Note that the name of the "provider" in your config has to match the name of the binary.

Note: The credential provider will only be used if the image matches a path in the list. Globbing may be used, but each glob can only match a single subdomain segment. So *.io does not match *.k8s.io.

Authentication

The AWS SDK credential chain is used to locate credentials for authenticating with AWS. For example, when you run the ECR credential provider on an EC2 instance, credentials are usually fetched from IMDS and no other configuration is necessary. If you do not run the ECR credential provider on EC2, you can specify credentials using environment variables, the ~/.aws/config file, or any other standard method in the credential chain.