[Feature] Set labels conditional spec selector

functions/go/set-labels/README.md

@@ -72,6 +72,25 @@ labels:
   fruit: apple
 ```
 
+The `set-labels` function adds the desired labels to more fields than just the one
+found in `.metadata`. For example, the `Deployment` resource has a `spec.selector`,
+which gets updated by the `set-labels` function by default. This is not always desired.
+
+To disable updating of `.spec.selectors`, define a `SetLabels` custom resource, and set
+`.options.setSelectorLabels` to `false` like so:
+
+```yaml
+apiVersion: fn.kpt.dev/v1alpha1
+kind: SetLabels
+metadata:
+  name: my-config
+labels:
+  color: orange
+  fruit: apple
+options:
+  setSelectorLabels: false # default is true
+```
+
 <!--mdtogo-->
 
 [labels]: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/

functions/go/set-labels/run.go

@@ -24,7 +24,18 @@ import (
 )
 
 func NewTransformer() fn.ResourceListProcessor {
-	return fn.WithContext(fn.Context{Context: context.Background()}, &setlabels.SetLabels{})
+	// Create a new SetLabels struct
+	labels := make(map[string]string)
+	options := map[string]bool{
+		"setSelectorLabels": true,
+	}
+	setLabels := &setlabels.SetLabels{
+		Labels:  labels,
+		Options: options,
+	}
+
+	// Return the SetLabels struct as a fn.ResourceListProcessor
+	return fn.WithContext(fn.Context{Context: context.Background()}, setLabels)
 }
 
 func run() error {

functions/go/set-labels/setlabels/transformer.go

@@ -20,8 +20,12 @@ var _ fn.Runner = &SetLabels{}
 // SetLabels supports the set-labels workflow, it uses Config to parse functionConfig, Transform to change the labels
 type SetLabels struct {
 	// labels is the desired labels
-	Labels map[string]string `json:"labels,omitempty"`
-	count  int
+	Labels  map[string]string `json:"labels,omitempty"`
+
+	// options is the configurable and optional options
+	Options map[string]bool   `json:"options,omitempty"`
+
+	count   int
 }
 
 // EmptyfnConfig is a workaround since kpt creates a FunctionConfig placeholder if users don't provide the functionConfig.
@@ -161,6 +165,11 @@ func hasSpecSelector(o *fn.KubeObject) bool {
 
 // setLabelsInSelector set labels for all selectors, including spec selector map, spec selector LabelSelector, LabelSelector in JobTemplate, and podSelector in NetworkPolicy, and
 func (p *SetLabels) setLabelsInSelector(o *fn.KubeObject) error {
+	// setSelectorLabels is true by default
+	if !p.Options["setSelectorLabels"] {
+		return nil
+	}
+
 	if hasSpecSelector(o) {
 		fieldPath := FieldPath{"spec", "selector"}
 		if err := p.updateLabels(&o.SubObject, fieldPath, p.Labels, true); err != nil {

tests/set-labels/deployment/.expected/diff.patch

@@ -0,0 +1,78 @@
+diff --git a/Kptfile b/Kptfile
+index ad493d3..917ae02 100644
+--- a/Kptfile
++++ b/Kptfile
+@@ -17,4 +17,4 @@ pipeline:
+     - image: gcr.io/kpt-fn/set-labels:unstable
+       configPath: fn-config-selector-labels-undefined.yaml
+       selectors:
+-        - name: the-deployment-selector-labels-undefined
+\ No newline at end of file
++        - name: the-deployment-selector-labels-undefined
+diff --git a/deployment.yaml b/deployment.yaml
+index 11be507..b03ae0a 100644
+--- a/deployment.yaml
++++ b/deployment.yaml
+@@ -4,6 +4,8 @@ metadata:
+   name: the-deployment-selector-labels-false
+   labels:
+     app: the-deployment
++    color: orange
++    fruit: apple
+ spec:
+   selector:
+     matchLabels:
+@@ -12,6 +14,8 @@ spec:
+     metadata:
+       labels:
+         app: the-deployment
++        color: orange
++        fruit: apple
+     spec:
+       containers:
+       - name: the-container
+@@ -23,14 +27,20 @@ metadata:
+   name: the-deployment-selector-labels-true
+   labels:
+     app: the-deployment
++    color: orange
++    fruit: apple
+ spec:
+   selector:
+     matchLabels:
+       app: the-deployment
++      color: orange
++      fruit: apple
+   template:
+     metadata:
+       labels:
+         app: the-deployment
++        color: orange
++        fruit: apple
+     spec:
+       containers:
+       - name: the-container
+@@ -42,15 +52,21 @@ metadata:
+   name: the-deployment-selector-labels-undefined
+   labels:
+     app: the-deployment
++    color: orange
++    fruit: apple
+ spec:
+   selector:
+     matchLabels:
+       app: the-deployment
++      color: orange
++      fruit: apple
+   template:
+     metadata:
+       labels:
+         app: the-deployment
++        color: orange
++        fruit: apple
+     spec:
+       containers:
+       - name: the-container
+-        image: the-image
+\ No newline at end of file
++        image: the-image

tests/set-labels/deployment/.expected/results.yaml

@@ -0,0 +1,21 @@
+apiVersion: kpt.dev/v1
+kind: FunctionResultList
+metadata:
+  name: fnresults
+exitCode: 0
+items:
+  - image: gcr.io/kpt-fn/set-labels:unstable
+    exitCode: 0
+    results:
+      - message: set 4 labels in total
+        severity: info
+  - image: gcr.io/kpt-fn/set-labels:unstable
+    exitCode: 0
+    results:
+      - message: set 6 labels in total
+        severity: info
+  - image: gcr.io/kpt-fn/set-labels:unstable
+    exitCode: 0
+    results:
+      - message: set 6 labels in total
+        severity: info

tests/set-labels/deployment/.krmignore

@@ -0,0 +1 @@
+.expected

tests/set-labels/deployment/Kptfile

@@ -0,0 +1,20 @@
+apiVersion: kpt.dev/v1
+kind: Kptfile
+metadata:
+  name: example
+  annotations:
+    config.kubernetes.io/local-config: "true"
+pipeline:
+  mutators:
+    - image: gcr.io/kpt-fn/set-labels:unstable
+      configPath: fn-config-selector-labels-false.yaml
+      selectors:
+        - name: the-deployment-selector-labels-false
+    - image: gcr.io/kpt-fn/set-labels:unstable
+      configPath: fn-config-selector-labels-true.yaml
+      selectors:
+        - name: the-deployment-selector-labels-true
+    - image: gcr.io/kpt-fn/set-labels:unstable
+      configPath: fn-config-selector-labels-undefined.yaml
+      selectors:
+        - name: the-deployment-selector-labels-undefined

tests/set-labels/deployment/deployment.yaml

@@ -0,0 +1,56 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: the-deployment-selector-labels-false
+  labels:
+    app: the-deployment
+spec:
+  selector:
+    matchLabels:
+      app: the-deployment
+  template:
+    metadata:
+      labels:
+        app: the-deployment
+    spec:
+      containers:
+      - name: the-container
+        image: the-image
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: the-deployment-selector-labels-true
+  labels:
+    app: the-deployment
+spec:
+  selector:
+    matchLabels:
+      app: the-deployment
+  template:
+    metadata:
+      labels:
+        app: the-deployment
+    spec:
+      containers:
+      - name: the-container
+        image: the-image
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: the-deployment-selector-labels-undefined
+  labels:
+    app: the-deployment
+spec:
+  selector:
+    matchLabels:
+      app: the-deployment
+  template:
+    metadata:
+      labels:
+        app: the-deployment
+    spec:
+      containers:
+      - name: the-container
+        image: the-image

tests/set-labels/deployment/fn-config-selector-labels-false.yaml

@@ -0,0 +1,11 @@
+apiVersion: fn.kpt.dev/v1alpha1
+kind: SetLabels
+metadata:
+  name: my-config
+  annotations:
+    config.kubernetes.io/local-config: "true"
+labels:
+  color: orange
+  fruit: apple
+options:
+  setSelectorLabels: false

tests/set-labels/deployment/fn-config-selector-labels-true.yaml

@@ -0,0 +1,11 @@
+apiVersion: fn.kpt.dev/v1alpha1
+kind: SetLabels
+metadata:
+  name: my-config
+  annotations:
+    config.kubernetes.io/local-config: "true"
+labels:
+  color: orange
+  fruit: apple
+options:
+  setSelectorLabels: true

tests/set-labels/deployment/fn-config-selector-labels-undefined.yaml

@@ -0,0 +1,9 @@
+apiVersion: fn.kpt.dev/v1alpha1
+kind: SetLabels
+metadata:
+  name: my-config
+  annotations:
+    config.kubernetes.io/local-config: "true"
+labels:
+  color: orange
+  fruit: apple