Add cross controller referenced resources to scheme (#302)

Description of changes:

* Add cross controller referenced resources to scheme
* Tested locally with successful reconciliation of referencing Subnet resource from ec2-controller inside VPCLink resource of apigatewayv2-controller

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

Author: vijtrip2

pkg/generate/ack/controller.go

@@ -241,12 +241,22 @@ func Controller(
 
 	// Next add the template for the main.go file
 	snakeCasedCRDNames := make([]string, 0)
+	// using Map to implement the Set
+	referencedServiceNamesMap := make(map[string]struct{})
 	for _, crd := range crds {
 		snakeCasedCRDNames = append(snakeCasedCRDNames, crd.Names.Snake)
+		for _, serviceName := range crd.ReferencedServiceNames() {
+			referencedServiceNamesMap[serviceName] = struct{}{}
+		}
+	}
+	referencedServiceNames := make([]string, 0)
+	for serviceName := range referencedServiceNamesMap {
+		referencedServiceNames = append(referencedServiceNames, serviceName)
 	}
 	cmdVars := &templateCmdVars{
 		metaVars,
 		snakeCasedCRDNames,
+		referencedServiceNames,
 	}
 	if err = ts.Add("cmd/controller/main.go", "cmd/controller/main.go.tpl", cmdVars); err != nil {
 		return nil, err
@@ -267,6 +277,10 @@ func Controller(
 type templateCmdVars struct {
 	templateset.MetaVars
 	SnakeCasedCRDNames []string
+	// ReferencedServiceNames contains the service name for ACK controllers whose
+	// resources are referenced inside the CRDs.
+	// Service name is go package name of AWS service in aws-sdk-go.
+	ReferencedServiceNames []string
 }
 
 // templateConfigVars contains template variables for the templates that require

templates/cmd/controller/main.go.tpl

@@ -19,8 +19,18 @@ import (
 	ackv1alpha1 "github.com/aws-controllers-k8s/runtime/apis/core/v1alpha1"
 	svcresource "github.com/aws-controllers-k8s/{{ .ServicePackageName }}-controller/pkg/resource"
 	svctypes "github.com/aws-controllers-k8s/{{ .ServicePackageName }}-controller/apis/{{ .APIVersion }}"
+{{- /* Import the go types from service controllers whose resources are referenced in this service controller.
+If these referenced types are not added to scheme, this service controller will not be able to read
+resources across service controller. */ -}}
+{{- $servicePackageName := .ServicePackageName }}
+{{- $apiVersion := .APIVersion }}
+{{- range $referencedServiceName := .ReferencedServiceNames }}
+{{- if not (eq $referencedServiceName $servicePackageName) }}
+    {{ $referencedServiceName }}apitypes "github.com/aws-controllers-k8s/{{ $referencedServiceName }}-controller/apis/{{ $apiVersion }}"
+{{- end }}
+{{- end }}
 	{{/* TODO(a-hilaly): import apis/* packages to register webhooks */}}
-	{{ $serviceAlias := .ServicePackageName }} {{range $crdName := .SnakeCasedCRDNames }}_ "github.com/aws-controllers-k8s/{{ $serviceAlias }}-controller/pkg/resource/{{ $crdName }}"
+	{{range $crdName := .SnakeCasedCRDNames }}_ "github.com/aws-controllers-k8s/{{ $servicePackageName }}-controller/pkg/resource/{{ $crdName }}"
 	{{end}}
 )
 
@@ -37,6 +47,11 @@ func init() {
 	{{/* TODO(a-hilaly): register all the apis/* schemes */}}
 	_ = svctypes.AddToScheme(scheme)
 	_ = ackv1alpha1.AddToScheme(scheme)
+{{- range $referencedServiceName := .ReferencedServiceNames }}
+{{- if not (eq $referencedServiceName $servicePackageName) }}
+    _ = {{ $referencedServiceName }}apitypes.AddToScheme(scheme)
+{{- end }}
+{{- end }}
 }
 
 func main() {