Customize Hook

Controller changes

The composite and decorator controller sync and finalize hooks will contain a new field, related.

This field is in the same format as children / ChildMap.

Customize Hook

If the customize hook is defined, Metacontroller will ask for which related objects, or classes of objects that your sync and finalize hooks need to know about.

This is useful for mapping across many objects. One example would be a controller that lets you specify ConfigMaps to be placed in every Namespace.

Another use-case is being able to reference other objects, e.g. the env section from a core Pod object.

If you don't define a customize hook, then the related section of the hooks will be empty.

The customize hook will not provide any information about the current state of the cluster. Thus, the set of related objects may only depend on the state of the parent object.

This hook may also accept other fields in future, for other customizations.

Customize Hook Request

A separate request will be sent for each parent object, so your hook only needs to think about one parent at a time.

The body of the request (a POST in the case of a webhook) will be a JSON object with the following fields:

FieldDescription
controllerThe whole CompositeController object, like what you might get from kubectl get compositecontroller <name> -o json.
parentThe parent object, like what you might get from kubectl get <parent-resource> <parent-name> -o json.

Customize Hook Response

The body of your response should be a JSON object with the following fields:

FieldDescription
relatedResourcesA list of JSON objects representing all the desired related resource label selectors.

The relatedResources field should contain a flat list of objects, not an associative array.

Each resource rule object should be a JSON object with the following fields:

FieldDescription
apiVersionThe API <group>/<version> of the parent resource, or just <version> for core APIs. (e.g. v1, apps/v1, batch/v1)
resourceThe canonical, lowercase, plural name of the parent resource. (e.g. deployments, replicasets, statefulsets)
labelSelectorA v1.LabelSelector object.
namespaceOptional. The Namespace to select in
namesOptional. A list of strings, representing individual objects to return

If the parent resource is cluster scoped and the related resource is namespaced, the namespace may be used to restrict which objects to look at. If the parent resource is namespaced, the related resources must come from the same namespace. Specifying the namespace is optional, but if specified must match.

Note that your webhook handler must return a response with a status code of 200 to be considered successful. Metacontroller will wait for a response for up to the amount defined in the Webhook spec.