Kubeconfig-merger: merging kubeconfig files into ~/.kube/config

Each new Kubernetes cluster usually comes with its own kubeconfig file, and getting it into ~/.kube/config means copying its cluster, user and context entries over by hand. Kubeconfig-merger is a small Go CLI that removes this step: kubeconfig files are simply dropped into a directory, and the application merges all of them into ~/.kube/config.

How it works

By default, kubeconfig files are kept as separate files in ~/.kube/config.d, one per cluster. The application:

  1. Walks the source directory recursively and collects every .yaml and .yml file
  2. Sets KUBECONFIG to the list of those files, using the path separator of the current OS (; on Windows, : elsewhere)
  3. Runs kubectl config view --merge --flatten, which merges the files and embeds certificates and keys inline instead of referencing them by path
  4. Writes the output to ~/.kube/config

The merging itself is delegated to kubectl, so kubectl must be installed and available in the PATH.

Usage

./kubeconfig-merger

A source directory other than ~/.kube/config.d can be specified with the -source flag:

./kubeconfig-merger -source /path/to/config/dir

Adding or removing a cluster then comes down to adding or removing a file in the source directory and running the merger again. Note that ~/.kube/config is overwritten each time, so it should only be edited through the files in the source directory.

Source code

The source code is available on GitHub. Binaries are built with GoReleaser through GitHub Actions.