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  • January 8, 2019

Kubernetes Command Line Tools

Mickey Boxell
Product Management

Kubernetes Command Line Tools

Introduction

If you are someone who frequently interacts with a Kubernetes cluster, you may find yourself frustrated by the time spent typing out repetitive commands. One way to reduce this frustration is through the use of CLI tools for kubectl, the Kubernetes command line interface. This article will highlight several tools used to simplify usage of kubectl and save you time.

Pre-requisites: The default prompt assumes you have the kubectl command line utility installed along with a Kubernetes cluster. Check out this article for instructions on installing kubectl. To get access to a Kubernetes cluster using Oracle Container Engine for Kubernetes (OKE) follow this friendly guide.

 

Shell Autocompletion: Autocompletion for Kubectl

If you find yourself spending too much time writing out long kubectl commands it would be worth your time to configure shell autocompletion. This is similar to shell completion in bash, zsh, etc. This tool is useful because it can be used to autocomplete all of the basic kubectl commands and also deployments, services, etc. from your cluster. Autocomplete pulls information from your current context, saving you from having to type out potentially lengthy deployment names. Check out this article for instructions on how to configure shell autocompletion for kubectl.

To use shell autocompletion with kubectl simply press tab while writing out a command.

For example we can type g and then press tab to autocomplete to get.

$ kubectl g [TAB]
$ kubectl get
 

Which means that when we type s you would expect pressing tab would autocomplete to service , but in this case there are more than a few options for words starting with s.

$ kubectl get s [TAB]
secrets                                signalfxs.config.istio.io
serviceaccounts                        solarwindses.config.istio.io
servicecontrolreports.config.istio.io  stackdrivers.config.istio.io
servicecontrols.config.istio.io        statefulsets.apps
serviceentries.networking.istio.io     statsds.config.istio.io
servicerolebindings.rbac.istio.io      stdios.config.istio.io
serviceroles.rbac.istio.io             storageclasses.storage.k8s.io
services
 

If you write out service you can tab to show all of the available services in your current namespace.

$ kubectl get service [TAB]
details      helloworld   kubernetes   productpage  ratings      reviews
 

To see the whole list of available commands, type kubectl followed by two tab's.

$ kubectl [TAB][TAB]
annotate       certificate    create         explain        plugin         set
api-resources  cluster-info   delete         expose         port-forward   taint
api-versions   completion     describe       get            proxy          top
apply          config         diff           label          replace        uncordon
attach         convert        drain          logs           rollout        version
auth           cordon         edit           options        run            wait
autoscale      cp             exec           patch          scale
 

 

 

kubectx & kubens: switch back and forth between Kubernetes contexts & namespaces

If you find yourself bouncing around between multiple Kubernetes contexts and/or multiple namespaces it can be helpful to have tools to shorten the process. Using kubectx you can easily list, switch, rename, and delete contexts. kubens simply lists and switches between name spaces. Both tools also support tab completion.

Check out this article for instructions about how to configure kubectx and kubens.

Additionally, you can make kubectx and kubens even more handy by adding an interactive menu, such as fzf. fzf is a command-line fuzzy finder that provides you with an interactive menu of contexts or namespaces to choose from.

Using kubectx

To list contexts:

$ kubectx
context-ctdazdbmi3t
docker-for-desktop
 

To switch contexts:

$ kubectx docker-for-desktop
Switched to context "docker-for-desktop".
 

To return to the previous context:

$ kubectx -
Switched to context "context-ctdazdbmi3t".
 

To rename a context:

$ kubectx oracle=context-ctdazdbmi3t
Context "context-ctdazdbmi3t" renamed to "oracle".
 

The same commands apply when kubectx is used with fzf. The only difference is the appearance of an interactive menu.

$ kubectx

> docker-for-desktop
  context-ctdazdbmi3t
  2/2
 

Using kubens

To list namespaces:

$ kubens
default
istio-system
kube-public
kube-system
sample
spinnaker
 

To switch namespaces:

$ kubens spinnaker
Context "context-ctdazdbmi3t" modified.
Active namespace is "spinnaker".
 

To return to the previous namespace:

$ kubens - 
Context "context-ctdazdbmi3t" modified.
Active namespace is "default"
 

Using kubectx with fzf

The same commands apply when kubens is used with fzf. The only difference is the appearance of an interactive menu.

$ kubens 

> default
  istio-system
  kube-public
  kube-system
  sample
  spinnaker
  6/6
 

 

kube-ps1: Kubernetes prompt for bash and zsh

kube-ps1 adds your current Kubernetes context and namespace to your prompt string. This tool saves you from having to type out kubectl config current-context every time you need to check your context or determine your current namespace. This is a simple change that can make interacting with your cluster a little easier.

Also, if you get tired of seeing your context and namespace, you can simply turn off kube-ps1 in your shell session with kubeoff. It can be turned back on with kubeon. To make it take effect globally across shell sessions add the -g flag to the end of the command.

Check out this article for instructions about how to configure kube-ps1.

After it has been installed, your shell should look something like this:
(⎈ |[context]:[namespace]) $
(⎈ |context-ctdazdbmi3t:default) $
 

Kubectl Aliases

Shell aliases for bash, zsh, etc. can be used to shorten any and all shell commands, not just those related to kubectl. In this case there is nothing additional to install in your environment. It is a good practice to separate the aliases related to kubectl into their own file and sourcing in your shell runtime config (e.g. bashrc). To create your own set of kubectl aliases, begin by creating a file in your $HOME directory, for instance .kube_alias:

$ vi .kube_alias
 

Begin by adding in a simple alias such as alias k='kubectl' and save the file. Edit your .bashrc or .zshrc file with the following:

[ -f ~/.kubectl_alias ] && source ~/.kubectl_alias

This will tell your shell to reference your newly created alias file. The next time you enter k in your shell, it will be treated as if you typed kubectl instead.

Aliases can be created to simplify any number of commands. For instance, if you find yourself frequently typing out kubectl get pods --all-namespaces to get a list of pods running in every namespace in your cluster, you could write an alias, such as kgpall to shorten the command. In your .kube_alias file that would look like this: alias kpgall="kubectl get pods --all-namespaces".

This page has a number of helpful aliases for use with Kubernetes. Even if you choose not to use this list, it can give you some helpful ideas for aliases to write yourself.

 

Conclusion

After reading this article I hope you have a better understanding of command line tools that make it easier for you to interact with Kubernetes. I also hope you feel inspired to explore the ecosystem of available tools or even create ones of your own.

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