Introduction

This is a simple example of configuring a MachineSet in OpenShift using Server-Side-Apply in Argo CD. This feature enables us to provide a partial version of the MachineSet that will be merged into the existing one.

MachineSet Naming

One of the challenges around managing MachineSets with GitOps is that each MachineSet gets a unique name which cannot be predicted in advance. Give this how can we provide a base configuration that can be used across all MachineSets in a fleet of customers?

In this example we will use kustomize to manage this. A base MachineSet exists in the folder components/apps/machineset/workers/base which can then be re-used at the cluster level. To handle the unique naming of the machineset we can simply use a kustomize override to patch the correct name into the partial yaml.

This kustomization for patching the name is located under the clusters/rhpds/apps/machineset/overrides/workers folder, here it is as an example:

patches:
  - patch: |-
      - op: replace
        path: /metadata/name
        value: cluster-lcfp9-k7g79-worker-us-east-2b
    target:
      group: machine.openshift.io
      kind: MachineSet
      name: example-worker