Fix ResourceInUseException when deleting cluster (#25)

Issue #, if available: aws-controllers-k8s/community#1191

Description of changes:
Adds a hook that checks to see all nodegroups have been deleted from the cluster before it attempts to delete the cluster itself

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

Author: RedbackThomson

apis/v1alpha1/ack-generate-metadata.yaml

@@ -1,7 +1,7 @@
 ack_generate_info:
-  build_date: "2022-02-28T18:05:07Z"
-  build_hash: 4724c496a77a35bd6d1d1a2cc415d342457a7463
-  go_version: go1.17.5
+  build_date: "2022-03-01T19:48:47Z"
+  build_hash: 7dff1f4590e623d17e58660b7dd1c66e22b5215a
+  go_version: go1.17.1
   version: v0.17.1
 api_directory_checksum: 50ce02741686341685d2a897fdcdd80c80e260d9
 api_version: v1alpha1

pkg/resource/addon/references.go

@@ -15,6 +15,7 @@ package cluster
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"
 
@@ -56,6 +57,10 @@ var (
 		fmt.Errorf("cluster in '%s' state, cannot be modified or deleted", StatusDeleting),
 		ackrequeue.DefaultRequeueAfterDuration,
 	)
+	requeueWaitWhileInUse = ackrequeue.NeededAfter(
+		errors.New("cluster is still in use, cannot be deleted"),
+		ackrequeue.DefaultRequeueAfterDuration,
+	)
 	RequeueAfterUpdateDuration = 15 * time.Second
 )
 
@@ -138,6 +143,19 @@ func returnClusterUpdating(r *resource) (*resource, error) {
 	return r, requeueAfterAsyncUpdate()
 }
 
+// clusterInUse returns true if the supplied cluster is still being used. It
+// determines this by checking if there are any nodegroups still attached to
+// the cluster.
+func (rm *resourceManager) clusterInUse(ctx context.Context, r *resource) (bool, error) {
+	nodes, err := rm.listNodegroups(ctx, r)
+	if err != nil {
+		return false, err
+	}
+
+	// Cluster is in use if # of nodegroups != 0
+	return (nodes != nil && len(nodes.Nodegroups) > 0), nil
+}
+
 func (rm *resourceManager) customUpdate(
 	ctx context.Context,
 	desired *resource,
@@ -267,3 +285,23 @@ func (rm *resourceManager) updateConfigResourcesVPCConfig(
 
 	return nil
 }
+
+func (rm *resourceManager) listNodegroups(
+	ctx context.Context,
+	r *resource,
+) (nodes *svcsdk.ListNodegroupsOutput, err error) {
+	rlog := ackrtlog.FromContext(ctx)
+	exit := rlog.Trace("rm.listNodegroups")
+	defer exit(err)
+	input := &svcsdk.ListNodegroupsInput{
+		ClusterName: r.ko.Spec.Name,
+	}
+
+	nodes, err = rm.sdkapi.ListNodegroupsWithContext(ctx, input)
+	rm.metrics.RecordAPICall("READ_MANY", "ListNodegroups", err)
+	if err != nil {
+		return nil, err
+	}
+
+	return nodes, nil
+}

pkg/resource/cluster/hook.go

@@ -1,3 +1,9 @@
 	if clusterDeleting(r) {
 		return r, requeueWaitWhileDeleting
 	}
+	inUse, err := rm.clusterInUse(ctx, r);
+	if err != nil {
+		return nil, err
+	} else if inUse {
+		return r, requeueWaitWhileInUse
+	}