RKE supports configuring pluggable add-ons in the cluster YML. Add-ons are used to deploy several cluster components including:

These add-ons require images that can be found under the system_images directive. For each Kubernetes version, there are default images associated with each add-on, but these can be overridden by changing the image tag in system_images.

There are a few things worth noting:

  • In addition to these pluggable add-ons, you can specify an add-on that you want deployed after the cluster deployment is complete.
  • As of v0.1.8, RKE will update an add-on if it is the same name.
  • Prior to v0.1.8, update any add-ons by using kubectl edit.

Critical and Non-Critical Add-ons

As of version v0.1.7, add-ons are split into two categories:

  • Critical add-ons: If these add-ons fail to deploy for any reason, RKE will error out.
  • Non-critical add-ons: If these add-ons fail to deploy, RKE will only log a warning and continue deploying any other add-ons.

Currently, only the network plug-in is considered critical. KubeDNS, ingress controllers and user-defined add-ons are considered non-critical.

Add-on deployment jobs

RKE uses Kubernetes jobs to deploy add-ons. In some cases, add-ons deployment takes longer than expected. As of with version v0.1.7, RKE provides an option to control the job check timeout in seconds. This timeout is set at the cluster level.

addon_job_timeout: 30

Add-on placement

Applies to v0.2.3 and higher

Component nodeAffinity nodeSelectorTerms nodeSelector Tolerations
Calico beta.kubernetes.io/os:NotIn:windows none - NoSchedule:Exists
- NoExecute:Exists
- CriticalAddonsOnly:Exists
Flannel beta.kubernetes.io/os:NotIn:windows none - operator:Exists
Canal beta.kubernetes.io/os:NotIn:windows none - NoSchedule:Exists
- NoExecute:Exists
- CriticalAddonsOnly:Exists
Weave beta.kubernetes.io/os:NotIn:windows none - NoSchedule:Exists
- NoExecute:Exists
CoreDNS node-role.kubernetes.io/worker:Exists beta.kubernetes.io/os:linux - NoSchedule:Exists
- NoExecute:Exists
- CriticalAddonsOnly:Exists
kube-dns - beta.kubernetes.io/os:NotIn:windows
- node-role.kubernetes.io/worker Exists		 none - NoSchedule:Exists
- NoExecute:Exists
- CriticalAddonsOnly:Exists
nginx-ingress - beta.kubernetes.io/os:NotIn:windows
- node-role.kubernetes.io/worker Exists		 none - NoSchedule:Exists
- NoExecute:Exists
metrics-server - beta.kubernetes.io/os:NotIn:windows
- node-role.kubernetes.io/worker Exists		 none - NoSchedule:Exists
- NoExecute:Exists