Microk8s Docker Registry

Published in

ITNEXT

3 min readAug 22, 2018

A friend once asked, why would one prefer microk8s over minikube?… We never spoke since. True story!

That was a hard question, especially for an engineer. The answer is not so obvious largely because it has to do with personal preferences. Let me show you why.

Microk8s-wise this is what you have to do to have a local Kubernetes cluster with a registry:

sudo snap install microk8s --edge --classic
microk8s.enable registry

How is this great?

It is super fast! A couple of hundreds of MB over the internet tubes and you are all set.
You skip the pain of going through the docs for setting up and configuring Kubernetes with persistent storage and the registry.

So why is this bad?

As a Kubernetes engineer you may want to know what happens under the hood. What got deployed? What images? Where?
As a Kubernetes user you may want to configure the registry. Where are the images stored? Can you change any access credentials?

Do you see why this is a matter of preference? Minikube is a mature solution for setting up a Kubernetes in a VM. It runs everywhere (even on windows) and it does only one thing, sets up a Kubernetes cluster.

On the other hand, microk8s offers Kubernetes as an application. It is opinionated and it takes a step towards automating common development workflows. Speaking of development workflows...

The full story with the registry

The registry shipped with microk8s is available on port 32000 of the localhost. It is an insecure registry because, let’s be honest, who cares about security when doing local development :) .

And it’s getting better, check this out! The docker daemon used by microk8s is configured to trust this insecure registry. It is this daemon we talk to when we want to upload images. The easiest way to do so is by using the microk8s.docker command coming with microk8s:

# Lets get a Docker file first
wget https://raw.githubusercontent.com/nginxinc/docker-nginx/ddbbbdf9c410d105f82aa1b4dbf05c0021c84fd6/mainline/stretch/Dockerfile# And build it
microk8s.docker build -t localhost:32000/nginx:testlocal . microk8s.docker push localhost:32000/nginx:testlocal

If you prefer to use an external docker client you should point it to the socket dockerd is listening on:
docker -H unix:///var/snap/microk8s/docker.sock ps

To use an image from the local registry just reference it in your manifests:

apiVersion: v1
kind: Pod
metadata:
  name: my-nginx
  namespace: default
spec:
  containers:
  - name: nginx
    image: localhost:32000/nginx:testlocal
  restartPolicy: Always

And deploy with:

microk8s.kubectl create -f the-above-awesome-manifest.yaml

Microk8s and registry

Recorded by kjackal

asciinema.org

What to keep from this post?

You want Kubernetes? We deliver it as a (sn)app!

You want to see your tool-chain in microk8s? Drop us a line. Send us a PR!

We are pleased to see happy Kubernauts!

Those of you who are here for the gossip. He was not that good of a friend (obviously!). We only met in a meetup :) !

References

Microk8s main site: http://microk8s.io
Microk8s repo: https://github.com/ubuntu/microk8s
Microk8s registry: https://github.com/ubuntu/microk8s/blob/master/docs/registry.md