How to build Kubernetes from source and test in Kind with VSCode & devcontainers
I found myself last week looking at a bit of code in K8s which I thought I could make better, so I set about trying to understand how to clone, change and test it.
Luckily K8s has some good docs , trust these over me as they’re a great gui de. This blog is more of a brain dump of how I got on trying with Devcontainers and VSCode.This is my first try at this so I’ve likely got lots of things wrong.
Roughly I knew what I needed as I’d heard about:
As the K8s build and testing cycle can use up quite a bit of machine power I didn’t want be doing all this on my laptop and ideally I wanted to capture all the setup in a nice repeatable way.
Enter DevContainers for VSCode, I’ve got them setup on my laptop to actually run on a meaty server for me and I can use them to capture all the setup requirements for building K8s.
After a lot of wrangling I got a Dockerfile and devcontainer.json file together which mount and install the required bits (warning: There may be lots wrong with this, I’m pretty new to the world of building K8s from source).
Now all I need to do is clone K8s, drop these two files into a .devcontainer folder and open the folder in VSCode. Once open you get prompted to open the folder in the devcontainer and away you go.
What do you do now?
- Make the change you want to make
- Build an image for kind with your changes:
kind build node-image --type bazel \
-v 5 --image kindest/node:lawrence
- Start a cluster based off that image:
kind create cluster --name lg \
--image kindest/node:lawrence
- You can run the e2e tests too (still getting to grips with this)
kubetest --up --test --down \
--deployment=kind \
--kind-node-image=kindest/node:lawrence \
--provider=skeleton
The best part? All of this runs nicely in VSCode like its running locally but behind the scenes it’s on a remote server. The left window is my laptop and the right is the server doing a build.
Let me try it
https://gist.github.com/lawrencegripper/0027a76b90539a9534a87c136c35c484
Current devcontainer setup (WIP)