Kubectl optimization

There are few tweaks that I found useful when working with kubectl to manage kubernetes cluster.

I'm running a cluster of Raspberry Pi.

Kubectl lets you manage your cluster from command line. By default it requires a lots of typing. A lot! When you need to use it on daily basis, these tweaks can save your fingers.

All of the tweaks are set in user's .bashrc. At the end there are all changes at once.

Kubectl alias

Instead of typing kubectl everytime (also note that when you have both kubectl and kubeadm, bash's tab completion doesn't help you a lot), I'm using simple k.

alias k=kubectl

Kubectl completion

This one helps you complete kubectl sub commands and parameters. It also supports completion of pod/svc/deploy/etc names. So if you have for example a single pod managed by replica set and deployment, it may be named as webcam-69d6fdd46c-kbvfk. The deployment itself is named webcam, replica set 69d6fdd46c and pod has the suffix kbvfk. When you need to get logs of the pod, you need to type the whole name. And this name is changed everytime the pod dies. With completion, you can just type k logs webcam, press tab and rest of the name will be populated.

source <(kubectl completion bash)
complete -F __start_kubectl kubectl k

The end of the second line (kubectl k) defines commands for which the completion should be used (kubectl and k in this case).

If your pod is in a different namespace than the default one, type the namespace before pod name, like k logs -n monitoring webcam and than press the tab.

Changing default namespace

By default, kubectl "default" namespace is stored in .kube/config, and whenever you are using kubectl for different namespace, you need to include -n or --namespace in your command. It's quite hard to change the default namespace in .kube/config, fortunately there is a tool to the rescue - kubens and kubectx.

It shows you all namespaces and contexts and lets change the defaults.

Kubens and kubectx alias

kubens and kubectx is still quite verbose, so aliases can help.

alias kns=kubens
alias kctx=kubectx

Kubens and kubectx completion

As with kubectl, even kubens/kns and kubectx/kctx supports completion.

_kube_namespaces()
{
  local curr_arg;
  curr_arg=${COMP_WORDS[COMP_CWORD]}
  COMPREPLY=( $(compgen -W "- $(kubectl get namespaces -o=jsonpath='{range .items[*].metadata.name}{@}{"\n"}{end}')" -- $curr_arg ) );
}
complete -F _kube_namespaces kubens kns

_kube_contexts()
{
  local curr_arg;
  curr_arg=${COMP_WORDS[COMP_CWORD]}
  COMPREPLY=( $(compgen -W "- $(kubectl config get-contexts --output='name')" -- $curr_arg ) );
}
alias kctx=kubectx
complete -F _kube_contexts kubectx kctx

Summary

• kubectl/k alias for kubectl.
• k completion.
• kubens for changing default .kube/config namespace.
• kubectx for changing .kube/config context.
• kns alias for kubens.
• kctx alias for kubectx.
• kubens/kns completion.
• kubectx/kctx completion.

Changes to .bashrc at once

# kubectl
alias k=kubectl
source <(kubectl completion bash)
complete -F __start_kubectl kubectl k

# kubens
_kube_namespaces()
{
  local curr_arg;
  curr_arg=${COMP_WORDS[COMP_CWORD]}
  COMPREPLY=( $(compgen -W "- $(kubectl get namespaces -o=jsonpath='{range .items[*].metadata.name}{@}{"\n"}{end}')" -- $curr_arg ) );
}
alias kns=kubens
complete -F _kube_namespaces kubens kns

# kubectx
_kube_contexts()
{
  local curr_arg;
  curr_arg=${COMP_WORDS[COMP_CWORD]}
  COMPREPLY=( $(compgen -W "- $(kubectl config get-contexts --output='name')" -- $curr_arg ) );
}
alias kctx=kubectx
complete -F _kube_contexts kubectx kctx