Gábor Hermann's blog

Local development with Kubernetes

It's worth investing in local Kubernetes setup if we're using Kubernetes. It can save a lot of time.


Nowadays, Kubernetes is part of development. E.g. we might tweak readiness probe together with application code. Using a local cluster gets us a much faster to development cycle compared to a real cluster. There are many reasons, but there's one big in my experience.

Building Docker image is slow when using a real cluster. Every time we make a code change we either need to push code to some CI/CD environment or build Docker image locally and push the image to a remote registry.


We will set up a

Then use it:

Before we get started, we'll need a Docker Desktop, a terminal, and a text editor. We use MacOS, but should mostly work on Linux too.

Setup local Kubernetes cluster

We're going to use k3d. It's an easy way to run k3s which is a very lightweight k8s distribution. I hope the names are confusing.

Install k3d:

brew install k3d

(See other installation methods if you're not on MacOS.)

Create cluster including local Docker image registry for being able to use local images:

k3d registry create registry.localhost --port 5000
k3d cluster create mycluster \
  --registry-use k3d-registry.localhost:5000 \
  --registry-config <(echo '{"mirrors":{"localhost:5000":{"endpoint":["http://k3d-registry.localhost:5000"]}}}')

Then we should see k3d-mycluster context:

kubectl config get-contexts

That context should be used from whatever Kubernetes interface (I recommend k9s).

Create script

Let's create an "application" that we can package in Docker. A simple script myscript.sh:


echo Hello local Kubernetes!

Package script in Docker

Then a Dockerfile so that we can package it:

FROM busybox

COPY myscript.sh myscript.sh

Build the image locally and push it to local registry.

docker build -t localhost:5000/myimage:latest .
docker push localhost:5000/myimage:latest

Run script on Kubernetes

We will run a Kubernetes Pod. We should create a spec for the Pod in pod.yml:

apiVersion: v1
kind: Pod
  name: mypod
  restartPolicy: Never
    - name: mycontainer
      image: localhost:5000/myimage:latest
      command: ["/bin/sh", "myscript.sh"]

Then we can create this Pod:

kubectl apply -f pod.yml

It probably already run instantly, and we can see the logs:

kubectl logs pod/mypod

It should say Hello local Kubernetes!.

Going further

Our application is probably going to be more complex. E.g. we can use Deployments, set up a Service, and port-forwarding so that we can look at our service in browser. But this really depends on application.


I do software: data crunching, functional programming, pet projects. This blog is to rant about these.

Hit me up on Twitter or email blHIDDEN TEXTog@gaborhermHIDDEN TEXT 2ann.org

Of course, opinions are my own, they do not reflect the opinions of any past, present, future, or parallel universe employer.