Use fzf to Supercharge Your kubectl Command

First let’s have a look at fzf, a super fast command line fuzzy finder. It’s mostly written in golang and there are so many ways to use it. In this note, I’ll just use it to select a value from a list in a terminal and then return it to next command.

When working with kubernetes, I open need to switch between namespaces in a cluster. The raw kubectl command for this is:

 kubectl config set-context --current --namespace='my-namespace'

But I don’t remember every namespace, do I? If auto-completion of kubectl is available I can double-tab and then get a list of namespaces like this:

This is not quite convenient, not at all. So I created this simple bash function using fzf to speed this up.

#select k8s namespace
function kns() {
  kubectl config set-context --current --namespace=$(kubectl get namespaces --output=jsonpath='{range .items[*]}{.metadata.name}{"\n"}'|fzf)
}

The kubectl get... command in the sub shell above simple output a list of available kubernetes namespaces and then pipe to fzf to make an interactive auto-completion. And then the selected namespace will be passed back to kubectl config ... command to actually set the namespace to current context. The result looks like this:

PS. I’ve put this and other handy shorthand functions here.

Use FZF to Speed Up KUBECTL

FZF is general purpose option selector for Linux command line. By default fzf is an super-upgrade for the ctrl-r command history finder, but it is helpful for almost any scenario where you need to pick 1 item from a list.

Here’s a tiny use case where I use fzf to select a kubernetes namespace and set it as the default namespace, just to save the effort to type --namespace flag everytime when I need to do something not in the default namespace.

#!/bin/bash
function kns() {
cns=$(kubectl get namespaces --output=jsonpath='{range .items[*]}{.metadata.name}{"\n"}'|fzf)
kubectl config set-context --current --namespace=$cns
}

Let me explain the script above step by step:

  1. kubectl get namespaces will list all namespaces currently accessible
  2. --output=jsonpath='{range .items[*]}{.metadata.name}{"\n"}' will only output the name of namespaces and 1 in each line
  3. |fzf to pipe the result from step 2 to fzf, a list will popup and becomes interactive for the user to choose one.
  4. kubectl config set-context --current --namespace=$cns will set the chosen namespace from step 3 as the default namespace

This is very convenient when there are not too many namespaces and when you need to work in different namespaces randomly. 🙂