Add addoption by annotation feature

These changes introduce a new feature gate called `ForceAdoptResources`
which allows users to provide the read required fields in the annotation
and an empty spec, and the controller would populate the resource
and adopt from AWS

apis/core/v1alpha1/annotations.go

@@ -81,4 +81,13 @@ const (
 	// the resource is read-only and should not be created/patched/deleted by the
 	// ACK service controller.
 	AnnotationReadOnly = AnnotationPrefix + "read-only"
+	// AnnotationForceAdoption is an annotation whose value is the identifier for whether
+	// we will force adoption or not. If this annotation is set to true on a CR, that
+	// means the user is indicating to the ACK service controller that it should
+	// force adoption of the resource.
+	AnnotationForceAdoption = AnnotationPrefix + "force-adoption"
+	// AnnotationAdoptionFields is an annotation whose value contains a json-like
+	// format of the requied fields to do a ReadOne when attempting to force-adopt
+	// a Resource
+	AnnotationAdoptionFields = AnnotationPrefix + "adoption-fields"
 )

pkg/featuregate/features.go

@@ -19,6 +19,10 @@ package featuregate
 import "fmt"
 
 const (
+	// ForcedAdoptResources is a feature gate for enabling forced adoption of resources
+	// by annotation
+	ForcedAdoptResources = "ForcedAdoptResources"
+
 	// ReadOnlyResources is a feature gate for enabling ReadOnly resources annotation.
 	ReadOnlyResources = "ReadOnlyResources"
 
@@ -32,9 +36,10 @@ const (
 // defaultACKFeatureGates is a map of feature names to Feature structs
 // representing the default feature gates for ACK controllers.
 var defaultACKFeatureGates = FeatureGates{
-	ReadOnlyResources: {Stage: Alpha, Enabled: false},
-	TeamLevelCARM:     {Stage: Alpha, Enabled: false},
-	ServiceLevelCARM:  {Stage: Alpha, Enabled: false},
+	ForcedAdoptResources: {Stage: Alpha, Enabled: false},
+	ReadOnlyResources:    {Stage: Alpha, Enabled: false},
+	TeamLevelCARM:        {Stage: Alpha, Enabled: false},
+	ServiceLevelCARM:     {Stage: Alpha, Enabled: false},
 }
 
 // FeatureStage represents the development stage of a feature.

pkg/runtime/reconciler.go

@@ -360,13 +360,91 @@ func (r *resourceReconciler) Sync(
 	isAdopted := IsAdopted(desired)
 	rlog.WithValues("is_adopted", isAdopted)
 
+	if r.cfg.FeatureGates.IsEnabled(featuregate.ForcedAdoptResources) {
+		isForcedAdoption := IsForcedAdoption(desired)
+		rlog.WithValues("is_forced_adoption", isForcedAdoption)
+
+		// If the resource is being adopted by force, we need to access
+		// the required field passed by annotation and attempt a read.
+		if isForcedAdoption && NeedAdoption(desired) {
+			rlog.Info("Adopting Resource")
+			extractedFields, err := ExtractAdoptionFields(desired)
+			if err != nil {
+				return desired, err
+			}
+			if extractedFields == nil {
+				// TODO(michaelhtm) figure out error here
+				return nil, fmt.Errorf("Failed extracting fields from annotation")
+			}
+			res := desired.DeepCopy()
+			err = res.PopulateResourceFromAnnotation(extractedFields)
+			if err != nil {
+				return nil, err
+			}
+			resolved := res
+			if hasRef, ok := extractedFields["hasReferences"]; ok && hasRef == "true" {
+				rlog.Enter("rm.ResolveReferences")
+				resolved, hasReferences, err := rm.ResolveReferences(ctx, r.apiReader, res)
+				rlog.Exit("rm.ResolveReferences", err)
+				if err != nil {
+					return ackcondition.WithReferencesResolvedCondition(res, err), err
+				}
+				if hasReferences {
+					resolved = ackcondition.WithReferencesResolvedCondition(resolved, err)
+				}
+			}
+
+			rlog.Enter("rm.EnsureTags")
+			err = rm.EnsureTags(ctx, resolved, r.sc.GetMetadata())
+			rlog.Exit("rm.EnsureTags", err)
+			if err != nil {
+				return resolved, err
+			}
+			rlog.Enter("rm.ReadOne")
+			latest, err = rm.ReadOne(ctx, resolved)
+			if err != nil {
+				return nil, err
+			}
+
+			if !r.rd.IsManaged(latest) {
+				if err = r.setResourceManaged(ctx, rm, latest); err != nil {
+					return nil, err
+				}
+
+				// Ensure tags again after adding the finalizer and patching the
+				// resource. Patching desired resource omits the controller tags
+				// because they are not persisted in etcd. So we again ensure
+				// that tags are present before performing the create operation.
+				rlog.Enter("rm.EnsureTags")
+				err = rm.EnsureTags(ctx, latest, r.sc.GetMetadata())
+				rlog.Exit("rm.EnsureTags", err)
+				if err != nil {
+					return latest, err
+				}
+			}
+			r.rd.MarkAdopted(latest)
+			latest, err = r.patchResourceMetadataAndSpec(ctx, rm, desired, latest)
+			if err != nil {
+				return latest, err
+			}
+			err = r.patchResourceStatus(ctx, desired, latest)
+			if err != nil {
+				return latest, err
+			}
+			rlog.Info("Resource Adopted")
+			return latest, nil
+		}
+	}
+
 	if r.cfg.FeatureGates.IsEnabled(featuregate.ReadOnlyResources) {
 		isReadOnly := IsReadOnly(desired)
 		rlog.WithValues("is_read_only", isReadOnly)
 
 		// NOTE(a-hilaly): When the time comes to support adopting resources
 		// using annotations, we will need to think a little bit more about
 		// the case where a user, wants to adopt a resource as read-only.
+		//
+		// NOTE(michaelhtm): Done, tnx :)
 
 		// If the resource is read-only, we enter a different code path where we
 		// only read the resource and patch the metadata and spec.

pkg/runtime/util.go

@@ -14,6 +14,7 @@
 package runtime
 
 import (
+	"encoding/json"
 	"strings"
 
 	corev1 "k8s.io/api/core/v1"
@@ -68,3 +69,50 @@ func IsReadOnly(res acktypes.AWSResource) bool {
 	}
 	return false
 }
+
+// IsForcedAdoption returns true if the supploed AWSResource has an annotation
+// indicating that it should be adopted
+func IsForcedAdoption(res acktypes.AWSResource) bool {
+	mo := res.MetaObject()
+	if mo == nil {
+		// Should never happen... if it does, it's buggy code.
+		panic("IsForcedAdoption received resource with nil RuntimeObject")
+	}
+	for k, v := range mo.GetAnnotations() {
+		if k == ackv1alpha1.AnnotationForceAdoption {
+			return strings.ToLower(v) == "true"
+		}
+	}
+	return false
+}
+
+func NeedAdoption(res acktypes.AWSResource) bool {
+	return IsForcedAdoption(res) && !IsAdopted(res)
+}
+
+func ExtractAdoptionFields(res acktypes.AWSResource) (map[string]string, error) {
+	fields := extractFieldsFromAnnotation(res)
+
+	extractedFields := &map[string]string{}
+	err := json.Unmarshal([]byte(fields), extractedFields)
+	if err != nil {
+		return nil, err
+	}
+
+	return *extractedFields, nil
+}
+
+func extractFieldsFromAnnotation(res acktypes.AWSResource) string {
+	mo := res.MetaObject()
+	if mo == nil {
+		// Should never happen... if it does, it's buggy code.
+		panic("ExtractRequiredFields received resource with nil RuntimeObject")
+	}
+
+	for k, v := range mo.GetAnnotations() {
+		if k == ackv1alpha1.AnnotationAdoptionFields {
+			return v
+		}
+	}
+	return ""
+}

pkg/types/aws_resource.go

@@ -48,4 +48,7 @@ type AWSResource interface {
 	SetStatus(AWSResource)
 	// DeepCopy will return a copy of the resource
 	DeepCopy() AWSResource
+	// PopulateResourceFromAnnotation will set the Spec or Status field that user
+	// provided from annotations
+	PopulateResourceFromAnnotation(fields map[string]string) error 
 }