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kubectl-ns

This repository implements a single kubectl plugin for switching the namespace that the current KUBECONFIG context points to. In order to remain as indestructive as possible, no previously existing contexts are modified.

Note: go-get or vendor this package as k8s.io/kubectl-ns.

This repository makes use of the genericclioptions in k8s.io/cli-runtime to generate a set of configuration flags which are in turn used to generate a raw representation of the user's KUBECONFIG, as well as to obtain configuration which can be used with RESTClients when sending requests to a kubernetes api server.

Details

The sample cli plugin uses the client-go library to patch an existing KUBECONFIG file in a user's environment in order to update context information to point the client to a new or existing namespace.

In order to be as non-destructive as possible, no existing contexts are modified in any way. Rather, the current context is examined, and matched against existing contexts to find a context containing the same "AuthInfo" and "Cluster" information, but with the newly desired namespace requested by the user.

Purpose

This is a fully-working example of how to build a kubectl plugin using the same set of tools and helpers available to kubectl.

Building + Running

# assumes you have a working KUBECONFIG
$ go build cmd/kubectl-ns.go
# place the built binary somewhere in your PATH
$ cp ./kubectl-ns /usr/local/bin

# you can now begin using this plugin as a regular kubectl command:
# update your configuration to point to "new-namespace"
$ kubectl ns new-namespace
# any kubectl commands you perform from now on will use "new-namespace"
$ kubectl get pod
NAME                READY     STATUS    RESTARTS   AGE
new-namespace-pod   1/1       Running   0          1h

# list all of the namespace in use by contexts in your KUBECONFIG
$ kubectl ns --list

# show the namespace that the currently set context in your KUBECONFIG points to
$ kubectl ns

Installing via Krew

Krew is a kubectl plugin package manager for kubectl plugins. This plugin is listed under the name change-ns in Krew's plugin index.

You can skip manual compilation and instead install this plugin via Krew by using the following steps (assumes you have Krew already installed):

kubectl krew update && kubectl krew install change-ns

Assuming you've installed this plugin using Krew, you will need to invoke it as "change-ns", instead of simply "ns":

# show the namespace that the currently set context in your KUBECONFIG points to
kubectl change-ns

Use Cases

This plugin can be used as a developer tool, in order to quickly view or change the current namespace that kubectl points to.

It can also be used as a means of showcasing usage of the cli-runtime set of utilities to aid in third-party plugin development.

This plugin's functionality is similar to that of the oc project command. This plugin has been tested against OpenShift and Kubernetes clusters using kubectl.

Cleanup

You can "uninstall" this plugin from kubectl by simply removing it from your PATH:

$ rm /usr/local/bin/kubectl-ns

Where does it come from?

This plugin is a fork of the sample-cli-plugin. It is maintained and updated here, as a separate effort, in order to make it available through plugin managers, such as Krew.