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kubeprompt

Built with Nix

Isolates KUBECONFIG in each shell and shows the current Kubernetes context/namespace in your prompt

prompt

Installation

Manual install

Pre-built binaries are available for linux and MacOS on the releases page.

Homebrew (macOS and Linux)

brew tap jlesquembre/kubeprompt https://github.com/jlesquembre/kubeprompt/
brew install kubeprompt

NixOS

kubeprompt is available in the Nix Packages collection.

To install it globally, add it to your systemPackages. If you just want to try it, you can do it in a Nix shell:

nix-shell -p kubeprompt

Usage

kubeprompt is shell-agnostic and thus works on any shell, but every shell has a different way to customize its prompt. Some examples:

fish shell:

function fish_prompt
  echo (kubeprompt -f default) '>'
end

Zsh:

PROMPT='$(kubeprompt -f default)'$PROMPT

Bash:

PS1="[\u@\h \W \$(kubeprompt -f default)]\$ "

kubeprompt will print to stdout information about the current cluster, but first it needs to be enabled. It is considered enabled if the environment variable KUBECONFIG is set to a file in the $TMP/kubeprompt directory. To enable it, just execute kubeprompt. This will spawn a new shell (based on your SHELL environment variable) and will copy your current kubeconfig to a new temporary file (it uses k8s cli-runtime)

kubeprompt command will print the current K8S context and namespace, if kubeprompt is enabled. If not, it will start a sub shell with kubeprompt enabled. The sub shell to launch depends on the value of the environment variable SHELL, starting a bash shell if is not defined.

To disable kubeprompt you just need to got back to the previous shell. You can do that with the exit command or with the CTRL+d shortcut.

Valid flags:

  • -f, --format custom format string
  • -t, --temp-config copies the current KUBECONFIG to a temporary file, used with direnv
  • -c, --check print information about kubeprompt status
  • -h, --help help for kubeprompt
  • -v, --version print the version

Usage with direnv

From version 0.4, kubeprompt can be integrated with direnv. In this case, there is no need to start a sub shell.

.envrc e.g.:

export KUBECONFIG=$(kubeprompt -t)

# Only required if you want to set the K8S context
kubectx minikube

If you use direnv with nix (you should!), use this instead:

shell.nix:

with import <nixpkgs> { };
pkgs.mkShell {
  buildInputs = [
    # ...
  ];
  shellHook = ''
    export KUBECONFIG=$(kubeprompt -t)
    kubectx minikube
  '';
}

See direnv Wiki: Nix integration for more info.

direnv limitations: It is not possible to clean up the temporary KUBECONFIG files created when you exit the shell. But those temporary files are usually deleted when you shutdown your system. If you don't use direnv and spawn a new subshell with kubeprompt, the temporary files are deleted after you exit the subshell.

Integration with other tools

kubeprompt tries to leverage and complement existing tools.

To read and create a copy of your KUBECONFIG, it uses k8s cli-runtime. You can expect the same behavior as with the kubectl command.

It plays well with kubectx, since it uses kubectl under the hood.

For the same reason, it also plays well with k9s.

Prompt customization

It is possible to customize the prompt using go templates. The templates have access to 3 variables, Ctx, Ns and Enabled, and to the color functions provided by Aurora, plus the Bold, Faint, Italic and Underline functions.

The default format is

{{if .Enabled}}(K8S {{.Ctx | Yellow | Bold}}|{{.Ns | Magenta | Bold}}){{end}}

You have 2 options to provide your format string, with -f / --format option, or setting the environment variable KUBEPROMPT_FORMAT. If both are provided, -f is used.

Some examples:

  • No colors:
'(⎈ {{.Ctx}}|{{.Ns}})'
  • Print only if kubeprompt is enabled:
'{{if .Enabled}}{{"⎈" | Black | BgWhite }} {{.Ctx}}|{{.Ns}}{{end}}'
  • Print k8s string with a different color if kubeprompt is enabled:
'{{if .Enabled}}{{"k8s"|Green|Bold}}{{else}}{{"k8s"|Red}}{{end}} {{.Ctx}}|{{.Ns}}'

Workflows

Usually you'll call kubeprompt -f default in your dot files. In the terminal, you usually want to call kubeprompt to enable it, because after it, you can be confident about the information in your terminal, since every terminal will have its own isolated kubeconfig.

You can decide if you want to show the kubernetes information always or only when kubeprompt is enabled. If you want to show the information always, I recommend to use different colors to know if kubeprompt is enabled or not. I consider the disabled color as a warning, because in this case, you cannot be sure if the information is accurate. Since your kubeconfig is global, other applications (or yourself in other terminal) can change the global kubernetes context.

F.A.Q.

Why to copy kubeconfig and start a sub shell?

If you are working with multiple contexts/namespaces in multiple terminals, all of them will modify the same kubeconfig file when you update the context/namespace. For more context, see kubernetes PR #60044

Let's suppose that you are working in 2 terminals with kubectl in context foo. Since you are using kubeprompt, your prompt shows that the context is foo. Now, you change the context in one terminal to bar, and after it you change the focus to the other terminal. Since the prompt information is static, in that terminal the prompt still says that the context is foo, but that information is old, and you could execute a command in the wrong context.

To avoid it, kubeprompt creates a copy of your current kubeconfig per terminal and sets the KUBECONFIG environment variable to that copy. If now you change the context or the namespace, only that terminal will be affected. If you want to disable kubeprompt on one terminal, you just need to press CTRL+d

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