Add static value source for replacement

Introduces `sourceValue` on replacement object for replacing from a
static value instead of sourcing from another object.

Solves #5516

api/filters/replacement/replacement.go

@@ -23,7 +23,7 @@ type Filter struct {
 // Filter replaces values of targets with values from sources
 func (f Filter) Filter(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
 	for i, r := range f.Replacements {
-		if r.Source == nil || r.Targets == nil {
+		if (r.SourceValue == nil && r.Source == nil) || r.Targets == nil {
 			return nil, fmt.Errorf("replacements must specify a source and at least one target")
 		}
 		value, err := getReplacement(nodes, &f.Replacements[i])
@@ -39,6 +39,13 @@ func (f Filter) Filter(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
 }
 
 func getReplacement(nodes []*yaml.RNode, r *types.Replacement) (*yaml.RNode, error) {
+	if r.SourceValue != nil && r.Source != nil {
+		return nil, fmt.Errorf("value and resource selectors are mutually exclusive")
+	}
+	if r.SourceValue != nil {
+		return yaml.NewScalarRNode(*r.SourceValue), nil
+	}
+
 	source, err := selectSourceNode(nodes, r.Source)
 	if err != nil {
 		return nil, err

api/filters/replacement/replacement_test.go

@@ -2829,6 +2829,70 @@ spec:
           create: true
 `,
 			expectedErr: "unable to find or create field \"spec.tls.5.hosts.5\" in replacement target: index 5 specified but only 0 elements found",
+		}, "replace with static value": {
+			input: `apiVersion: v1
+kind: Deployment
+metadata:
+  name: deploy
+spec:
+  template:
+    spec:
+      containers:
+      - image: nginx:1.7.9
+        name: nginx-tagged
+      - image: postgres:1.8.0
+        name: postgresdb
+`,
+			replacements: `replacements:
+- sourceValue: custom/postgres:1.9.0
+  targets:
+  - select:
+      kind: Deployment
+      name: deploy
+    fieldPaths:
+    - spec.template.spec.containers.[name=postgresdb].image
+`,
+			expected: `apiVersion: v1
+kind: Deployment
+metadata:
+  name: deploy
+spec:
+  template:
+    spec:
+      containers:
+      - image: nginx:1.7.9
+        name: nginx-tagged
+      - image: custom/postgres:1.9.0
+        name: postgresdb
+`,
+		}, "source value and selector error": {
+			input: `apiVersion: v1
+kind: Deployment
+metadata:
+  name: deploy
+spec:
+  replicas: 1
+  template:
+    spec:
+      containers:
+      - image: nginx:1.7.9
+        name: nginx-tagged
+      - image: postgres:1.8.0
+        name: postgresdb
+`,
+			replacements: `replacements:
+- source:
+    kind: Deployment
+    name: deploy
+  sourceValue: 2
+  targets:
+  - select:
+      kind: Deployment
+      name: deploy
+    fieldPaths:
+    - spec.replicas
+`,
+			expectedErr: "value and resource selectors are mutually exclusive",
 		},
 	}
 

api/types/replacement.go

@@ -20,6 +20,9 @@ type Replacement struct {
 
 	// The N fields to write the value to.
 	Targets []*TargetSelector `json:"targets,omitempty" yaml:"targets,omitempty"`
+
+	// Used to define an static value
+	SourceValue *string `json:"sourceValue,omitempty" yaml:"sourceValue,omitempty"`
 }
 
 // SourceSelector is the source of the replacement transformer.