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Configure the Aggregation Layer

Configuring the aggregation layer allows the Kubernetes apiserver to be extended with additional APIs, which are not part of the core Kubernetes APIs.

• Before you begin
• Enable Kubernetes Apiserver flags
• What's next

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikube, or you can use one of these Kubernetes playgrounds:

• Katacoda
• Play with Kubernetes

To check the version, enter kubectl version.

Note: There are a few setup requirements for getting the aggregation layer working in your environment to support mutual TLS auth between the proxy and extension apiservers. Kubernetes and the kube-apiserver have multiple CAs, so make sure that the proxy is signed by the aggregation layer CA and not by something else, like the master CA.

Enable Kubernetes Apiserver flags

Enable the aggregation layer via the following kube-apiserver flags. They may have already been taken care of by your provider.

--requestheader-client-ca-file=<path to aggregator CA cert>
--requestheader-allowed-names=front-proxy-client
--requestheader-extra-headers-prefix=X-Remote-Extra-
--requestheader-group-headers=X-Remote-Group
--requestheader-username-headers=X-Remote-User
--proxy-client-cert-file=<path to aggregator proxy cert>
--proxy-client-key-file=<path to aggregator proxy key>

Warning: Do not reuse a CA that is used in a different context unless you understand the risks and the mechanisms to protect the CA’s usage.

If you are not running kube-proxy on a host running the API server, then you must make sure that the system is enabled with the following kube-apiserver flag:

--enable-aggregator-routing=true

What's next

• Setup an extension api-server to work with the aggregation layer.
• For a high level overview, see Extending the Kubernetes API with the aggregation layer.
• Learn how to Extend the Kubernetes API Using Custom Resource Definitions.

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