Add Region() to ResourceMetadata struct and AWSResourceIdentifiers interface (#79)

Currently when a resource is created without setting a region in the
annotations, the controller uses either the namespace annotation or the
controller region flag. This causes the controller to miss manage the
resource if they are restart with a different region, or if run a second
controller using a different region flag.

This patch adds a new field to `ResourceMetadata` struct and
`AWSResourceIdentifiers` interface to store the AWS region in which
the resource is created/should be managed. This patch also updates the
`reconciler.getRegion` method to lookup for a region in the
status.ResourceMetadata before trying to get one from the
resource/namespace annotations or the controller configuration.

Addresses aws-controllers-k8s/community#1220

This patch will also require some changes to the code-generator.

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

Author: a-hilaly

apis/core/v1alpha1/resource_metadata.go

@@ -30,4 +30,6 @@ type ResourceMetadata struct {
 	// OwnerAccountID is the AWS Account ID of the account that owns the
 	// backend AWS service API resource.
 	OwnerAccountID *AWSAccountID `json:"ownerAccountID"`
+	// Region is the AWS region in which the resource exists or will exist.
+	Region *AWSRegion `json:"region"`
 }

mocks/pkg/types/aws_resource_identifiers.go

@@ -827,14 +827,23 @@ func (r *resourceReconciler) getRoleARN(
 	return ackv1alpha1.AWSResourceName(roleARN)
 }
 
-// getRegion returns the AWS region that the given resource is in or should be
-// created in. If the CR have a region associated with it, it is used. Otherwise
-// we look for the namespace associated region, if that is set we use it. Finally
-// if none of these annotations are set we use the use the region specified in the
-// configuration is used
+// getRegion returns the region the resource exists in, or if the resource
+// has yet to be created, the region the resource *should* be created in.
+//
+// If the resource has not yet been created, we look for the AWS region
+// in the following order of precedence:
+//  - The resource's `services.k8s.aws/region` annotation, if present
+//  - The resource's Namespace's `services.k8s.aws/region` annotation, if present
+//  - The controller's `--aws-region` CLI flag
 func (r *resourceReconciler) getRegion(
 	res acktypes.AWSResource,
 ) ackv1alpha1.AWSRegion {
+	// first try to get the region from the status.resourceMetadata
+	metadataRegion := res.Identifiers().Region()
+	if metadataRegion != nil {
+		return *metadataRegion
+	}
+
 	// look for region in CR metadata annotations
 	resAnnotations := res.MetaObject().GetAnnotations()
 	region, ok := resAnnotations[ackv1alpha1.AnnotationRegion]

pkg/runtime/reconciler.go

@@ -27,4 +27,6 @@ type AWSResourceIdentifiers interface {
 	// this means the resource has not yet been created in the backend AWS
 	// service.
 	ARN() *ackv1alpha1.AWSResourceName
+	// Region is the AWS region in which the resource exists or will exist.
+	Region() *ackv1alpha1.AWSRegion
 }