Kubernetes clusters run cluster addons atop Kubernetes itself. Addons may be considered essential for bootstrapping (non-optional), important (highly recommended), or optional.
Several addons are considered essential. CoreOS cluster creation tools ensure these addons are included. Kubernetes clusters deployed via the Matchbox examples or using our Terraform Modules include these addons as well.
kube-proxy is deployed as a DaemonSet.
kube-dns is deployed as a Deployment.
The Container Linux Update Operator (i.e. CLUO) coordinates reboots of auto-updating Container Linux nodes so that one node reboots at a time and nodes are drained before reboot. CLUO enables the auto-update behavior Container Linux clusters are known for, but does it in a Kubernetes native way. Deploying CLUO is strongly recommended.
update-operator deployment and
kubectl apply -f examples/addons/cluo/update-operator.yaml kubectl apply -f examples/addons/cluo/update-agent.yaml
Note, CLUO replaces
locksmithd reboot coordination. The
update_engine systemd unit on hosts still performs the Container Linux update check, download, and install to the inactive partition.