Snap showing how to use the configuration launcher in MicroK8s.

Create a YAML file called launcher/configuration/content.yaml with the launch configuration you want to apply to the MicroK8s instance. In this example snap, we only enable a few addons.

The configuration schema can be found in Configuration. Also see full.yaml for an example.

# launcher/configuration/content.yaml
---
version: 0.1.0
addons:
  - name: dns
  - name: rbac
  - name: ingress

Create one or more tar archives containing OCI images that will be sideloaded into the cluster and add them under launcher/sideload/<image>.tar. The filename does not matter, but the file extension must be .tar.

By default, this snap only contains the pause image (registry.k8s.io/pause:3.7) due to size considerations.

# retrieve pause.tar from a running instance:
microk8s ctr images export-local pause.tar registry.k8s.io/pause:3.7

# copy to launcher/sideload/
mkdir -p launcher/sideload
cp pause.tar launcher/sideload/pause.tar

Build the snap using snapcraft. This will produce a content-demo-microk8s_<version>_<arch>.snap file.

snapcraft

Optionally, upload and release the snap to the Snap Store:

snapcraft upload ./content-demo-microk8s_*.snap --release latest/edge

Install microk8s from a strict channel:

sudo snap install microk8s --channel=latest/edge/strict

Install the snap carrying the configuration. In this case the snap is content-demo-microk8s:

sudo snap install content-demo-microk8s --channel=latest/edge

Connect the configuration interface:

sudo snap connect microk8s:configuration content-demo-microk8s

After the configuration is applied, disconnect the interface:

sudo snap disconnect microk8s:configuration content-demo-microk8s:configuration

The end goal of this snap is to deliver a configuration yaml file to a MicroK8s cluster. To do so it implements the slot side of a content interface:

slots:
  configuration:
    interface: content
    content: configuration
    source:
      read:
        - $SNAP/launcher

On the other end of the content interface (the plug) a MicroK8s instance will search for the configuration yaml file and apply the requests setup.

• MicroK8s.io
• MicroK8s repository
• Content interface