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 existing contexts are modified.
Note: go-get or vendor this package as
This particular example demonstrates how to perform basic operations such as:
- How to create a new custom command that follows kubectl patterns
- How to obtain a user's KUBECONFIG settings and modify them
- How to make general use of the provided "cli-runtime" set of helpers for kubectl and third-party plugins
It 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.
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.
This is an example of how to build a kubectl plugin using the same set of tools and helpers available to kubectl.
# assumes you have a working KUBECONFIG
$ GO111MODULE="on" 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
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 supports shell completion when used through kubectl. To enable shell completion for the plugin
you must copy the file
./kubectl_complete-ns somewhere on
$PATH and give it executable permissions.
./kubectl_complete-ns script shows a hybrid approach to providing completions:
- it uses the builtin
__completecommand provided by Cobra for flags
- it calls
kubectlto obtain the list of namespaces to complete arguments (note that a more elegant approach would be to have the
kubectl-nsprogram itself provide completion of arguments by implementing Cobra's
ValidArgsFunctionto fetch the list of namespaces, but it would then be a less varied example)
One can then do things like:
$ kubectl ns <TAB>
default kube-node-lease kube-public kube-system
$ kubectl ns --<TAB>
--as -- Username to impersonate for the operation. User could be a regular user or a service account in a namespace.
--as-group -- Group to impersonate for the operation, this flag can be repeated to specify multiple groups.
--as-uid -- UID to impersonate for the operation.
--cache-dir -- Default cache directory
Note: kubectl v1.26 or higher is required for shell completion to work for plugins.
You can "uninstall" this plugin from kubectl by simply removing it from your PATH:
$ rm /usr/local/bin/kubectl-ns
HEAD of this repository will match HEAD of k8s.io/apimachinery and k8s.io/client-go.
Where does it come from?
sample-cli-plugin is synced from
Code changes are made in that location, merged into k8s.io/kubernetes and
later synced here.