Understanding the KubeConfig File: Insights from Building KubeTidy

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As someone who works with numerous customers and frequently builds landing zones using Infrastructure as Code (IaC), I often find myself spinning up and tearing down Azure Kubernetes Service (AKS) clusters in quick succession. These clusters often only stay up for a few minutes, but each time, my KubeConfig file grows larger and more disorganized, filled with outdated clusters, users, and contexts.

This experience led me to dig deeper into how the KubeConfig file works. I realized that keeping this file clean and efficient was becoming a bigger challenge as the number of clusters I interacted with increased. That’s why I decided to create KubeTidy, a tool designed to help manage and tidy up KubeConfig files.

In this post, I’ll share what I’ve learned about the KubeConfig file, why it tends to become bloated, and how KubeTidy helps solve these problems. Plus, I’ll touch on some existing tools I explored, and why I felt compelled to build something new.

What is a KubeConfig File?

A KubeConfig file is a configuration file that Kubernetes uses to manage connections to one or more clusters. It stores information about clusters, users, and contexts, allowing Kubernetes tools (such as kubectl) to authenticate and interact with different clusters.

The default KubeConfig file is typically located at ~/.kube/config, but you can manage multiple files and merge them as needed.

Main Sections of a KubeConfig File

1. Clusters: Contains the details of Kubernetes clusters, including the API server endpoint.

2. Users: Stores credentials (such as tokens or certificates) used to authenticate to the clusters.

3. Contexts: Defines a relationship between a user and a cluster. This is used to switch between environments.

4. Current Context: Specifies which context is currently active, meaning which cluster and user combination is being used.

Managing the KubeConfig File with Kubectl

You can use kubectl to interact with the KubeConfig file. Here are a few key commands:

• View your KubeConfig file:
  • kubectl config view
• Set the active context:
  • kubectl config use-context <context-name>
• Add a new cluster:
  • kubectl config set-cluster <cluster-name> --server=https://<cluster-endpoint>
• Add a new user:
  • kubectl config set-credentials <user-name> --token=<token>

While these commands make it easier to manage your KubeConfig file, over time, the file can become bloated with clusters, users, and contexts that are no longer in use—especially if you frequently create short-lived clusters like I do.

The Problem: KubeConfig File Bloat

In my work, testing AKS clusters for just a few minutes at a time, I noticed that my KubeConfig file was quickly becoming cluttered. Even though clusters would be deleted, their references remained in the KubeConfig file, along with user credentials and contexts that were no longer valid.

This growing list of outdated clusters made it harder to switch between active environments and increased the risk of misconfigurations or errors. Cleaning up the file manually was tedious and error-prone.

Why Existing Tools Weren’t Enough

I explored other tools that aimed to solve the problem of managing KubeConfig files, but I found them either outdated, lacking in the features I needed, or difficult to get started with. Some tools required you to build the software yourself, while others involved using an additional tool to even download the software.

I needed a solution that:

1. Was easy to get up and running without extra dependencies.
2. Make a backup before any changes were made.
3. Could efficiently clean up clusters, users, and contexts that were no longer relevant.
4. Would allow me to focus on my work rather than on manual file management.

Introducing KubeTidy

That’s when I decided to build KubeTidy, a simple tool designed to help Kubernetes users keep their KubeConfig files clean and manageable.

KubeTidy automatically removes stale or unused clusters, users, and contexts from your KubeConfig file, ensuring that it remains tidy and relevant. Here are some of the key benefits of KubeTidy:

• Automatically Cleans Stale Entries: It identifies and removes clusters, users, and contexts that are no longer in use.
• Streamlines Configuration: Keeps your file organized so that you only see relevant information.
• Improves Performance: A cleaner file reduces the risk of confusion and misconfigurations when switching between clusters.

Using KubeTidy is incredibly simple. Once installed (you can find out how in the readme at kubetidy.io just run:

This command will clean up your KubeConfig file, leaving only the active and necessary entries.

Why I Built KubeTidy

As someone who regularly works with multiple Kubernetes clusters and helps clients set up cloud infrastructure, I needed a way to manage the ever-growing KubeConfig file without constantly worrying about cleaning it up manually.

KubeTidy was built to solve this problem, and I’m excited to share it with the Kubernetes community. It’s open source, and I’m happy to receive pull requests, issues, or any feedback to make it better. You can find the project at KubeTidy.io.

If you’ve experienced similar frustrations with your KubeConfig file, I encourage you to give KubeTidy a try and let me know how it works for you!

Conclusion

The KubeConfig file is a vital part of working with Kubernetes, but it can quickly get out of control as you interact with multiple clusters and environments. By understanding the structure of the KubeConfig file and using tools like kubectl and KubeTidy, you can keep your configuration clean, manageable, and efficient.

If you’ve ever struggled with a bloated KubeConfig file, check out KubeTidy. I’m looking forward to hearing your thoughts, ideas, and feedback on how to make it even better!