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MicroK8s

MicroK8s is a lightweight, pre-packaged Kubernetes distribution which is easy to use and works well for small deployments.

Install

Install MicroK8s 1.19.1 or greater from Snap on all your nodes. https://microk8s.io/

# To install
sudo snap install microk8s --classic --channel=1.22/stable

# Or to upgrade
sudo snap refresh microk8s --classic --channel=1.22/stable

sudo usermod -a -G microk8s jonathan
sudo chown -f -R jonathan ~/.kube
microk8s status --wait-ready

Cluster

Enable microk8s HA mode on all nodes, which allows any of the worker nodes to also behave as a master, instead of just being a worker node. This must be enabled before nodes are joined to the master. https://microk8s.io/docs/high-availability

microk8s enable ha-cluster

Enable microk8s clustering, which allows you to add multiple worker nodes to your existing master node https://microk8s.io/docs/clustering

On the first node:

[jonathan@kube01 ~]$ microk8s add-node
From the node you wish to join to this cluster, run the following:
microk8s join 192.168.0.41:25000/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Then execute the join command on the other nodes, to join them to the master. Verify that they are correctly joined:

[jonathan@kube01 ~]$ microk8s kubectl get nodes
NAME                         STATUS   ROLES    AGE     VERSION
kube02.jonathangazeley.com   Ready    <none>   27m     v1.18.8-33+c9c9e3f85f05f9
kube01.jonathangazeley.com   Ready    <none>   6d16h   v1.18.8-33+c9c9e3f85f05f9
kube03.jonathangazeley.com   Ready    <none>   86s     v1.18.8-33+c9c9e3f85f05f9

Finally make sure that full HA mode is enabled:

[jonathan@kube01 ~]$ microk8s status
microk8s is running
high-availability: yes
  datastore master nodes: 192.168.0.41:19001 192.168.0.42:19001 192.168.0.43:19001
  datastore standby nodes: none
addons:
  enabled:
...

We've already checked that all 3 nodes are up. Now let's make sure pods are being scheduled on all nodes:

[jonathan@kube01 ~]$ kubectl get pods --all-namespaces -o wide
NAMESPACE     NAME                                                READY   STATUS              RESTARTS   AGE    IP             NODE                      
kube-system   calico-node-bqqqd                                   1/1     Running             0          112m   192.168.0.41   kube01.jonathangazeley.com
kube-system   calico-node-z4sxd                                   1/1     Running             0          110m   192.168.0.43   kube03.jonathangazeley.com
kube-system   calico-kube-controllers-847c8c99d-4qblz             1/1     Running             0          115m   10.1.58.1      kube01.jonathangazeley.com
kube-system   coredns-86f78bb79c-t2sgt                            1/1     Running             0          109m   10.1.111.65    kube02.jonathangazeley.com
kube-system   calico-node-t5skc                                   1/1     Running             0          111m   192.168.0.42   kube02.jonathangazeley.com
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