Kubernetes Operator Charms

Charmed Kubernetes is built with Juju's Charmed Operators. These operators are not limited to being deployed only on 'machines' (cloud instances, local VMs or metal) but many Charmed Operators are designed to be deployed on Kubernetes too. Additional features of Charmed Kubernetes are often supplied as Kubernetes Operator charms (for example, the Multus charm which provides multiple container network capability). To make full use of these operators, some additional setup of the Charmed Kubernetes cluster is required, as explained below.

Adding your cluster to the Juju controller

To manage operators within the cluster, Juju needs to be made aware of it and given the details of the cluster. If you are currently using kubectl with your Charmed Kubernetes cluster, you may already have performed the step of retrieving the cluster information from Charmed Kubernetes:

juju ssh kubernetes-control-plane/leader -- cat config > ~/.kube/config

This fetches the cluster information directly from Charmed Kubernetes and stores it in the default location (Note: if you run multiple clusters you may wish to merge these files rather than simple replace them).

Next, add your Kubernetes cluster as a cloud to your Juju controller:

juju add-k8s ck8s --controller $(juju switch | cut -d: -f1)

You may replace ck8s with whatever name you want to use to refer to this cluster.

Finally, to be able to deploy operators you will need to create a Juju model in the cluster:

juju add-model my-k8s-model ck8s

Again, you should replace my-k8s-model with a name you want to use to refer to this Kubernetes model. As well as creating a Juju model, this action will also create a Kubernetes namespace of the same name which you can use to easily monitor or manage operators you install on the cluster.