Adding Ability to MergePatch CRDs properly (#488)

* adding ability to merge patch crds properly

* added test for instance creation in an operator

* added specific error case for UnsupportedMediaType StrategicMergePatch

* added Kubernetes helper function and fixed linter

* linter fix

pkg/controller/planexecution/planexecution_controller.go

@@ -499,11 +499,33 @@ func (r *ReconcilePlanExecution) Reconcile(request reconcile.Request) (reconcile
 						log.Printf("Error getting patch between truth and obj: %v\n", err)
 					} else {
 						err = r.Client.Patch(context.TODO(), truth, client.ConstantPatch(types.StrategicMergePatchType, rawObj))
-						log.Printf("PlanExecutionController: CreateOrUpdate Patch: %v", err)
+						if err != nil {
+							// Right now applying a Strategic Merge Patch to custom resources does not work. There is
+							// certain metadata needed, which when missing, leads to an invalid Content-Type Header and
+							// causes the request to fail.
+							// ( see https://github.com/kubernetes-sigs/kustomize/issues/742#issuecomment-458650435 )
+							//
+							// We temporarily solve this by checking for the specific error when a SMP is applied to
+							// custom resources and handle it by defaulting to a Merge Patch.
+							//
+							// The error message for which we check is:
+							// 		the body of the request was in an unknown format - accepted media types include:
+							//			application/json-patch+json, application/merge-patch+json
+							//
+							// 		Reason: "UnsupportedMediaType" Code: 415
+							if errors.IsUnsupportedMediaType(err) {
+								err = r.Client.Patch(context.TODO(), truth, client.ConstantPatch(types.MergePatchType, rawObj))
+								if err != nil {
+									log.Printf("PlanExecutionController: CreateOrUpdate MergePatch: %v", err)
+								}
+							} else {
+								log.Printf("PlanExecutionController: CreateOrUpdate StrategicMergePatch: Unknown Error: %v", err)
+							}
+						}
 					}
 				} else {
 					//create
-					log.Printf("PlanExecutionController: CreateOrUpdate Object not present")
+					log.Println("PlanExecutionController: CreateOrUpdate Object not present")
 					err = r.Client.Create(context.TODO(), obj)
 					log.Printf("PlanExecutionController: CreateOrUpdate Create: %v", err)
 				}

test/integration/create-operator-in-operator/00-dream.yaml

@@ -0,0 +1,50 @@
+## Dream is the umbrella operator that tests the creation of instances within an operator
+apiVersion: kudo.k8s.io/v1alpha1
+kind: Operator
+metadata:
+  labels:
+    controller-tools.k8s.io: "1.0"
+  name: dream
+---
+apiVersion: kudo.k8s.io/v1alpha1
+kind: OperatorVersion
+metadata:
+  labels:
+    controller-tools.k8s.io: "1.0"
+  name: dream-v1
+spec:
+  version: "1.0.0"
+  connectionString: ""
+  operator:
+    name: dream
+    kind: Operator
+  templates:
+    operator.yaml: |
+      apiVersion: kudo.k8s.io/v1alpha1
+      kind: Instance
+      metadata:
+        name: operator
+      spec:
+        operatorVersion:
+          kind: OperatorVersion
+          name: test-operator-1.0
+          namespace: default
+        parameters:
+          REPLICAS: "0"
+  tasks:
+    operator:
+      resources:
+        - operator.yaml
+  parameters:
+    - name: Param
+      description: "Sample parameter"
+      default: "dream-in-a-dream"
+  plans:
+    deploy:
+      strategy: serial
+      phases:
+        - name: dependencies
+          steps:
+            - name: operator
+              tasks:
+                - operator

test/integration/create-operator-in-operator/01-assert.yaml

@@ -0,0 +1,20 @@
+apiVersion: kudo.k8s.io/v1alpha1
+kind: Instance
+metadata:
+  name: dream1
+status:
+  status: COMPLETE
+---
+apiVersion: kudo.k8s.io/v1alpha1
+kind: Instance
+metadata:
+  name: dream1-operator
+status:
+  status: COMPLETE
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: dream1-operator-nginx
+spec:
+  replicas: 0

test/integration/create-operator-in-operator/01-install.yaml

@@ -0,0 +1,11 @@
+apiVersion: kudo.k8s.io/v1alpha1
+kind: Instance
+metadata:
+  labels:
+    controller-tools.k8s.io: "1.0"
+    operator: dream
+  name: dream1
+spec:
+  operatorVersion:
+    name: dream-v1
+    kind: OperatorVersion