Running k0s in Docker#
In this tutorial you'll create a k0s cluster on top of docker. By default, both controller and worker are run in the same container to provide an easy local testing "cluster". The tutorial also shows how to add additional worker nodes to the cluster.
Docker environment on Mac, Windows or Linux. Get Docker.
The k0s containers are published both on Docker Hub and GitHub. The examples in this page show Docker Hub, because it's more simple to use. Using GitHub requires a separate authentication (not covered here). Alternative links:
1. Start k0s#
You can run your own k0s in Docker easily with:
docker run -d --name k0s --hostname k0s --privileged -v /var/lib/k0s -p 6443:6443 docker.io/k0sproject/k0s:latest
2. Create additional workers (optional)#
If you want to attach multiple workers nodes into the cluster you can then distribute your application containers to separate workers.
First, we need a join token for the worker:
token=$(docker exec -t -i k0s k0s token create --role=worker)
Then create and join a new worker by running the container with:
docker run -d --name k0s-worker1 --hostname k0s-worker1 --privileged -v /var/lib/k0s docker.io/k0sproject/k0s:latest k0s worker $token
Repeat for as many workers you need, and have resources for. :)
3. Access your cluster#
You can access your cluster with kubectl:
docker exec k0s kubectl get nodes
Alternatively, grab the kubeconfig file with
docker exec k0s cat /var/lib/k0s/pki/admin.conf and paste it e.g. into Lens.
Docker Compose (alternative)#
You can also run k0s with Docker Compose:
version: "3.9" services: k0s: container_name: k0s image: docker.io/k0sproject/k0s:latest command: k0s controller --config=/etc/k0s/config.yaml --enable-worker hostname: k0s privileged: true volumes: - "/var/lib/k0s" tmpfs: - /run - /var/run ports: - "6443:6443" network_mode: "bridge" environment: K0S_CONFIG: |- apiVersion: k0s.k0sproject.io/v1beta1 kind: Cluster metadata: name: k0s # Any additional configuration goes here ...
No custom Docker networks#
Currently, we cannot run k0s nodes if the containers are configured to use custom networks e.g. with
--net my-net. This is caused by the fact that Docker sets up a custom DNS service within the network and that messes up CoreDNS. We know that there are some workarounds possible, but they are bit hackish. And on the other hand, running k0s cluster(s) in bridge network should not cause issues.
- Installing with k0sctl for deploying and upgrading multi-node clusters with one command
- Control plane configuration options for example for networking and datastore configuration
- Worker node configuration options for example for node labels and kubelet arguments
- Support for cloud providers for example for load balancer or storage configuration
- Installing the Traefik Ingress Controller, a tutorial for ingress deployment