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108 lines
4.7 KiB
Markdown
108 lines
4.7 KiB
Markdown
<!-- BEGIN MUNGE: UNVERSIONED_WARNING -->
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<!-- BEGIN STRIP_FOR_RELEASE -->
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
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width="25" height="25">
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<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>
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If you are using a released version of Kubernetes, you should
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refer to the docs that go with that version.
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<strong>
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The latest 1.0.x release of this document can be found
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[here](http://releases.k8s.io/release-1.0/docs/admin/accessing-the-api.md).
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Documentation for other releases can be found at
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[releases.k8s.io](http://releases.k8s.io).
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</strong>
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--
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<!-- END STRIP_FOR_RELEASE -->
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<!-- END MUNGE: UNVERSIONED_WARNING -->
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# Configuring APIserver ports
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This document describes what ports the Kubernetes apiserver
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may serve on and how to reach them. The audience is
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cluster administrators who want to customize their cluster
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or understand the details.
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Most questions about accessing the cluster are covered
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in [Accessing the cluster](../user-guide/accessing-the-cluster.md).
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## Ports and IPs Served On
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The Kubernetes API is served by the Kubernetes apiserver process. Typically,
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there is one of these running on a single kubernetes-master node.
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By default the Kubernetes APIserver serves HTTP on 2 ports:
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1. Localhost Port
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- serves HTTP
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- default is port 8080, change with `--insecure-port` flag.
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- defaults IP is localhost, change with `--insecure-bind-address` flag.
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- no authentication or authorization checks in HTTP
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- protected by need to have host access
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2. Secure Port
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- default is port 6443, change with `--secure-port` flag.
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- default IP is first non-localhost network interface, change with `--bind-address` flag.
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- serves HTTPS. Set cert with `--tls-cert-file` and key with `--tls-private-key-file` flag.
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- uses token-file or client-certificate based [authentication](authentication.md).
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- uses policy-based [authorization](authorization.md).
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3. Removed: ReadOnly Port
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- For security reasons, this had to be removed. Use the [service account](../user-guide/service-accounts.md) feature instead.
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## Proxies and Firewall rules
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Additionally, in some configurations there is a proxy (nginx) running
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on the same machine as the apiserver process. The proxy serves HTTPS protected
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by Basic Auth on port 443, and proxies to the apiserver on localhost:8080. In
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these configurations the secure port is typically set to 6443.
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A firewall rule is typically configured to allow external HTTPS access to port 443.
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The above are defaults and reflect how Kubernetes is deployed to Google Compute Engine using
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kube-up.sh. Other cloud providers may vary.
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## Use Cases vs IP:Ports
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There are three differently configured serving ports because there are a
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variety of uses cases:
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1. Clients outside of a Kubernetes cluster, such as human running `kubectl`
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on desktop machine. Currently, accesses the Localhost Port via a proxy (nginx)
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running on the `kubernetes-master` machine. The proxy can use cert-based authentication
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or token-based authentication.
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2. Processes running in Containers on Kubernetes that need to read from
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the apiserver. Currently, these can use a [service account](../user-guide/service-accounts.md).
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3. Scheduler and Controller-manager processes, which need to do read-write
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API operations. Currently, these have to run on the same host as the
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apiserver and use the Localhost Port. In the future, these will be
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switched to using service accounts to avoid the need to be co-located.
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4. Kubelets, which need to do read-write API operations and are necessarily
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on different machines than the apiserver. Kubelet uses the Secure Port
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to get their pods, to find the services that a pod can see, and to
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write events. Credentials are distributed to kubelets at cluster
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setup time. Kubelet and kube-proxy can use cert-based authentication or token-based
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authentication.
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## Expected changes
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- Policy will limit the actions kubelets can do via the authed port.
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- Scheduler and Controller-manager will use the Secure Port too. They
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will then be able to run on different machines than the apiserver.
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<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
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[]()
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<!-- END MUNGE: GENERATED_ANALYTICS -->
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