Resource Discrimination Based on Desired State in Dependent Resources

[csviri]

If there are multiple resources of same type we use resource discriminators in Dependent Resources to identify the one that is managed by the dependent resource. Usually those discriminate by name, in most use cases. In terms of KubernetesDependentResource the default behavior could be improved in a way, that it would take a desired state and based on the name/namespace of the desired state would select the managed resource from the resources. So there will be no need for resource discriminator in most of the cases.

This is a bit more problematic for external resources, however there the POJO representing the resource could implement an interface that would mark the id(s) of the managed resource

[metacosm]

This idea sounds interesting but could you elaborate with a concrete example, please?

[csviri]

Consider this sample:

java-operator-sdk/operator-framework/src/test/java/io/javaoperatorsdk/operator/sample/multiplemanageddependentsametype/MultipleManagedDependentResourceReconciler.java

Lines 16 to 22 in af77064

	@ControllerConfiguration(dependents = {
	@Dependent(type = MultipleManagedDependentResourceConfigMap1.class,
	useEventSourceWithName = CONFIG_MAP_EVENT_SOURCE),
	@Dependent(type = MultipleManagedDependentResourceConfigMap2.class,
	useEventSourceWithName = CONFIG_MAP_EVENT_SOURCE)
	})
	public class MultipleManagedDependentResourceReconciler

Where both Config Map Dependents needs a discriminator:

@KubernetesDependent(resourceDiscriminator = ConfigMap1Discriminator.class)
public class MultipleManagedDependentResourceConfigMap1

However that discriminator typically what just does is maps primary resource to name (+namespaces) of the secondary resource. However based on desired state we already could know the name/namespace of the resource to select. So we could just override in this case for KubernetesDependentResource the getSecondaryResource to get the desired and if there are more of a type select one based on the name+namespace of the desired.