Server resources can be updated by using the configPatches section of the custom resource. Any field of the Talos machine config can be overridden on a per-machine basis using this method. The format of these patches is based on JSON 6902 that you may be used to in tools like kustomize.

Any patches specified in the server resource are processed by the Metal Metadata Server before it returns a Talos machine config for a given server at boot time.

A set of patches may look like this:

kind: Server
  name: 00000000-0000-0000-0000-d05099d33360
    - op: replace
      path: /machine/install
        disk: /dev/sda
    - op: replace
      path: /cluster/network/cni
        name: "custom"
          - ""

Testing Configuration Patches

While developing config patches it is usually convenient to test generated config with patches before actual server is provisioned with the config.

This can be achieved by querying the metadata server endpoint directly:

$ curl http://$PUBLIC_IP:9091/configdata?uuid=$SERVER_UUID
version: v1alpha1

Replace $PUBLIC_IP with the Sidero IP address and $SERVER_UUID with the name of the Server to test against.

If metadata endpoint returns an error on applying JSON patches, make sure config subtree being patched exists in the config. If it doesn't exist, create it with the op: add above the op: replace patch.

Combining Patches from Multiple Sources

Config patches might be combined from multiple sources (Server, ServerClass), which is explained in details in Metadata section.