Add set-default-labels function

Author: yuwenma

examples/set-default-labels-nested-package/.expected/diff.patch

@@ -0,0 +1,51 @@
+diff --git a/app1_ghost/resources.yaml b/app1_ghost/resources.yaml
+index 2e6dcbd..935a47b 100644
+--- a/app1_ghost/resources.yaml
++++ b/app1_ghost/resources.yaml
+@@ -2,6 +2,8 @@ apiVersion: apps/v1
+ kind: Deployment
+ metadata:
+   name: ghost
++  labels:
++    app.kubernetes.io/name: root-app
+ spec:
+   replicas: 2
+   template:
+@@ -14,4 +16,10 @@ spec:
+             - containerPort: 2368
+           env:
+             - name: url
+-              value: http://my-blog.com
+\ No newline at end of file
++              value: http://my-blog.com
++    metadata:
++      labels:
++        app.kubernetes.io/name: root-app
++  selector:
++    matchLabels:
++      app.kubernetes.io/name: root-app
+diff --git a/app2_mysql/resources.yaml b/app2_mysql/resources.yaml
+index 88d0df7..be45a8d 100644
+--- a/app2_mysql/resources.yaml
++++ b/app2_mysql/resources.yaml
+@@ -2,6 +2,8 @@ apiVersion: apps/v1
+ kind: Deployment
+ metadata:
+   name: mysql
++  labels:
++    app.kubernetes.io/name: root-app
+ spec:
+   template:
+     spec:
+@@ -11,5 +13,11 @@ spec:
+           ports:
+             - name: mysql
+               containerPort: 3306
++    metadata:
++      labels:
++        app.kubernetes.io/name: root-app
+   strategy:
+     type: Recreate
++  selector:
++    matchLabels:
++      app.kubernetes.io/name: root-app

examples/set-default-labels-nested-package/.krmignore

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

examples/set-default-labels-nested-package/Kptfile

@@ -0,0 +1,9 @@
+apiVersion: kpt.dev/v1
+kind: Kptfile
+metadata:
+  name: root-app
+  annotations:
+    config.kubernetes.io/local-config: "true"
+pipeline:
+  mutators:
+    - image: gcr.io/kpt-fn/set-default-labels:unstable

examples/set-default-labels-nested-package/README.md

@@ -0,0 +1,39 @@
+# set-default-labels: Nested Package Example
+
+### Overview
+
+This example shows how to run [`set-default-labels`] in a nested KPT package. 
+
+### Fetch the example package
+
+Get the example package by running the following commands:
+
+```shell
+$ kpt pkg get https://github.com/GoogleContainerTools/kpt-functions-catalog.git/examples/set-default-labels-nested-package root-app
+```
+
+Take a look at the `Kptfile`, it has the `set-default-labels` configured. Note: you do not need to specify the function config via `configPath` or `configMap`. 
+
+```yaml
+apiVersion: kpt.dev/v1
+kind: Kptfile
+metadata:
+  name: your-app
+pipeline:
+  mutators:
+    - image: gcr.io/kpt-fn/set-default-labels:unstable
+```
+
+### Function invocation
+
+Invoke the function:
+
+```shell
+$ kpt fn render root-app
+```
+
+### Expected result
+A [recommended label] `app.kubernetes.io/name: root-app` using the root package name is added to all the resources `labels` and `matchLabels` fields.
+
+[`set-default-labels`]: https://catalog.kpt.dev/set-default-labels/v0.1/
+[recommended label]: https://kubernetes.io/docs/concepts/overview/working-with-objects/common-labels/

examples/set-default-labels-nested-package/app1_ghost/Kptfile

@@ -0,0 +1,8 @@
+apiVersion: kpt.dev/v1
+kind: Kptfile
+metadata:
+  name: app1_ghost
+  annotations:
+    config.kubernetes.io/local-config: "true"
+info:
+  description: sample description

examples/set-default-labels-nested-package/app1_ghost/resources.yaml

@@ -0,0 +1,17 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: ghost
+spec:
+  replicas: 2
+  template:
+    spec:
+      containers:
+        - name: blog
+          image: ghost:2.6-alpine
+          imagePullPolicy: Always
+          ports:
+            - containerPort: 2368
+          env:
+            - name: url
+              value: http://my-blog.com

examples/set-default-labels-nested-package/app2_mysql/Kptfile

@@ -0,0 +1,8 @@
+apiVersion: kpt.dev/v1
+kind: Kptfile
+metadata:
+  name: app2_mysql
+  annotations:
+    config.kubernetes.io/local-config: "true"
+info:
+  description: sample description

examples/set-default-labels-nested-package/app2_mysql/resources.yaml

@@ -0,0 +1,15 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: mysql
+spec:
+  template:
+    spec:
+      containers:
+        - name: mysql
+          image: mysql:5.7
+          ports:
+            - name: mysql
+              containerPort: 3306
+  strategy:
+    type: Recreate

functions/go/Makefile

@@ -37,6 +37,7 @@ FUNCTIONS := \
 	set-enforcement-action \
 	set-image \
 	set-labels \
+	set-default-labels \
 	set-namespace \
 	set-project-id \
 	source-gcloud-config \

functions/go/set-default-labels/README.md

@@ -0,0 +1,62 @@
+# set-default-labels
+
+## Overview
+
+<!--mdtogo:Short-->
+
+The `set-default-labels` function applies KPT label convention to your KPT package.
+
+
+### `app.kubernetes.io/name` 
+
+Running the function can add this label using the value from the root `Kptfile` name.
+
+This convention believes that all KRM resources under the same kpt package should be served for a specific application.
+An application (or KPT package) can be composed by other applications (nested sub KPT packages). 
+So the function can accept multiple Kptfile and use the root Kptfile to set the app name.
+
+<!--mdtogo-->
+
+You can learn more about recommended labels [here][recommended labels].
+
+<!--mdtogo:Long-->
+
+## Usage
+
+This function should be run in a KPT package. It does not require function config.
+
+### Run the function once
+```shell
+$ kpt fn eval --image set-default-labels:unstable
+```
+
+### Run the function in a Kpt pipeline
+
+```shell
+# add the function to Kptfile
+$ kpt fn eval -t mutator -s -i set-default-labels:unstable
+```
+
+```shell
+# check Kptfile
+$ cat Kptfile
+
+apiVersion: kpt.dev/v1
+kind: Kptfile
+metadata:
+  name: set-default-label-example
+  annotations:
+    config.kubernetes.io/local-config: "true"
+pipeline:
+  mutators:
+    - image: gcr.io/kpt-fn/set-default-labels:unstable
+```
+
+```shell
+# run the function in a CI pipeline
+$ kpt fn render
+```
+<!--mdtogo-->
+
+
+[recommended labels]: https://kubernetes.io/docs/concepts/overview/working-with-objects/common-labels/