Merge pull request #27220 from xordspar0/patch-1

Document using generators in Deployments

Author: k8s-ci-robot

content/en/docs/tasks/manage-kubernetes-objects/kustomization.md

@@ -114,6 +114,98 @@ metadata:
   name: example-configmap-2-g2hdhfc6tk
 ```
 
+To use a generated ConfigMap in a Deployment, reference it by the name of the configMapGenerator. Kustomize will automatically replace this name with the generated name.
+
+This is an example deployment that uses a generated ConfigMap:
+
+```yaml
+# Create a application.properties file
+cat <<EOF >application.properties
+FOO=Bar
+EOF
+
+cat <<EOF >deployment.yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: my-app
+  labels:
+    app: my-app
+spec:
+  selector:
+    matchLabels:
+      app: my-app
+  template:
+    metadata:
+      labels:
+        app: my-app
+    spec:
+      containers:
+      - name: app
+        image: my-app
+        volumeMount:
+        - name: config
+          mountPath: /config
+      volumes:
+      - name: config
+        configMap:
+          name: example-configmap-1
+EOF
+
+cat <<EOF >./kustomization.yaml
+resources:
+- deployment.yaml
+configMapGenerator:
+- name: example-configmap-1
+  files:
+  - application.properties
+EOF
+```
+
+Generate the ConfigMap and Deployment:
+
+```shell
+kubectl kustomize ./
+```
+
+The generated Deployment will refer to the generated ConfigMap by name:
+
+```yaml
+apiVersion: v1
+data:
+  application.properties: |
+    FOO=Bar
+kind: ConfigMap
+metadata:
+  name: example-configmap-1-g4hk9g2ff8
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app: my-app
+  name: my-app
+spec:
+  selector:
+    matchLabels:
+      app: my-app
+  template:
+    metadata:
+      labels:
+        app: my-app
+    spec:
+      containers:
+      - image: my-app
+        name: app
+        volumeMount:
+        - mountPath: /config
+          name: config
+      volumes:
+      - configMap:
+          name: example-configmap-1-g4hk9g2ff8
+        name: config
+```
+
 #### secretGenerator
 
 You can generate Secrets from files or literal key-value pairs. To generate a Secret from a file, add an entry to the `files` list in `secretGenerator`. Here is an example of generating a Secret with a data item from a file:
@@ -170,6 +262,53 @@ metadata:
 type: Opaque
 ```
 
+Like ConfigMaps, generated Secrets can be used in Deployments by refering to the name of the secretGenerator:
+
+```shell
+# Create a password.txt file
+cat <<EOF >./password.txt
+username=admin
+password=secret
+EOF
+
+cat <<EOF >deployment.yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: my-app
+  labels:
+    app: my-app
+spec:
+  selector:
+    matchLabels:
+      app: my-app
+  template:
+    metadata:
+      labels:
+        app: my-app
+    spec:
+      containers:
+      - name: app
+        image: my-app
+        volumeMount:
+        - name: password
+          mountPath: /secrets
+      volumes:
+      - name: password
+        secret:
+          secretName: example-secret-1
+EOF
+
+cat <<EOF >./kustomization.yaml
+resources:
+- deployment.yaml
+secretGenerator:
+- name: example-secret-1
+  files:
+  - password.txt
+EOF
+```
+
 #### generatorOptions
 
 The generated ConfigMaps and Secrets have a content hash suffix appended. This ensures that a new ConfigMap or Secret is generated when the contents are changed. To disable the behavior of appending a suffix, one can use `generatorOptions`. Besides that, it is also possible to specify cross-cutting options for generated ConfigMaps and Secrets.