Added 'versioned-explicit-ref' annotation

pkg/kapp/diff/explicit_versioned_ref.go

@@ -0,0 +1,70 @@
+// Copyright 2020 VMware, Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+package diff
+
+import (
+	"fmt"
+)
+
+type VersionedRefDesc struct {
+	Namespace string `json:"namespace"`
+	APIGroup  string `json:"apiGroup"`
+	Kind      string `json:"kind"`
+	Name      string `json:"name"`
+}
+
+type ExplicitVersionedRefAnn struct {
+	References []VersionedRefDesc `json:"references"`
+}
+
+type ExplicitVersionedRef struct {
+	Resource   VersionedResource
+	Annotation ExplicitVersionedRefAnn
+}
+
+const (
+	explicitReferenceKey = "kapp.k14s.io/versioned-explicit-ref"
+)
+
+func NewExplicitVersionedRef(res VersionedResource, annotation ExplicitVersionedRefAnn) *ExplicitVersionedRef {
+	return &ExplicitVersionedRef{res, annotation}
+}
+
+func (e *ExplicitVersionedRef) IsReferenced() bool {
+	refList := e.refStringList()
+	resRef := e.resourceRefString()
+
+	for _, v := range refList {
+		if v == resRef {
+			return true
+		}
+	}
+
+	return false
+}
+
+func (e *ExplicitVersionedRef) refStringList() []string {
+	list := []string{}
+	for _, v := range e.Annotation.References {
+		if v.APIGroup == "core" {
+			v.APIGroup = ""
+		}
+
+		list = append(list, fmt.Sprintf("%s/%s/%s/%s", v.Namespace, v.APIGroup, v.Kind, v.Name))
+	}
+	return list
+}
+
+func (e *ExplicitVersionedRef) resourceRefString() string {
+	return e.Resource.UniqVersionedKey().String()
+}
+
+/*
+Annotation with a list of references in JSON format:
+
+kapp.k14s.io/versioned-explicit-ref: '{ "references": [ { "namespace": <resource-namespace>, "apiGroup":  <resource-apiGroup>, "kind" : <resource-kind>, "name":  <resource-name> } ] }'
+
+"namespace" need not be assigned a value for cluster-scoped resources.
+"apiGroup" need not be assigned a value for resources belonging to "core" API group.
+*/

pkg/kapp/diff/versioned_resource.go

@@ -83,11 +83,35 @@ func (d VersionedResource) updateAffected(rule ctlconf.TemplateRule, rs []ctlres
 			ReplacementFunc: d.buildObjRefReplacementFunc(affectedObjRef),
 		}
 
+		resourceExplicitKey := fmt.Sprintf("%s.%s", explicitReferenceKey, ctlres.NewUniqueResourceKey(d.res).String())
+		explicitReferenceMod := ctlres.StringMapAppendMod{
+			ResourceMatcher: ctlres.AllMatcher{},
+			Path:            ctlres.NewPathFromStrings([]string{"metadata", "labels"}),
+			KVs: map[string]string{
+				resourceExplicitKey: d.res.Name(),
+			},
+		}
+
 		for _, res := range rs {
 			err := mod.Apply(res)
 			if err != nil {
 				return err
 			}
+
+			if val, found := res.Annotations()[explicitReferenceKey]; found {
+				annotation := ExplicitVersionedRefAnn{}
+				err := json.Unmarshal([]byte(val), &annotation)
+				if err != nil {
+					return fmt.Errorf("Error unmarshalling explicit references : %s", err)
+				}
+
+				if NewExplicitVersionedRef(d, annotation).IsReferenced() {
+					err = explicitReferenceMod.Apply(res)
+					if err != nil {
+						return err
+					}
+				}
+			}
 		}
 	}