add inline patch document

examples/inlinePatch.md

@@ -0,0 +1,265 @@
+[Strategic Merge Patch]: https://github.com/kubernetes/community/blob/master/contributors/devel/sig-api-machinery/strategic-merge-patch.md
+[JSON Patch]: https://tools.ietf.org/html/rfc6902
+
+# Demo: Inline Patch
+
+A kustomization file supports patching in three ways:
+- patchesStrategicMerge: A list of patch files where each file is parsed as a [Stragetic Merge Patch].
+- patchesJSON6902: A list of patches and associated targetes, where each file is parsed as a [JSON Patch] and can only be applied to one target resource.
+- patches: A list of patches and their associated targets. The patch can be applied to multiple objects. It auto detects whether the patch is a [Strategic Merge Patch] or [JSON Patch].
+
+Since 3.2.0, all three support inline patch, where the patch content is put inside the kustomization file as a single string. With this feature, no separate patch files need to be created.
+
+Make a base kustomization containing a Deployment resource.
+<!-- @createKustomization @test -->
+```
+DEMO_HOME=$(mktemp -d)
+
+BASE=$DEMO_HOME/base
+mkdir $BASE
+
+cat <<EOF >$BASE/kustomization.yaml
+resources:
+- deployments.yaml
+EOF
+
+cat <<EOF >$BASE/deployments.yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: deploy
+spec:
+  template:
+    metadata:
+      labels:
+        foo: bar
+    spec:
+      containers:
+        - name: nginx
+          image: nginx
+          args:
+          - one
+          - two
+EOF
+```
+
+
+## Inline Patch for PatchesStrategicMerge
+
+Create an overlay and add an inline patch in `patchesStrategicMerge` field to the kustomization file
+to change the image from `nginx` to `nginx:latest`.
+
+<!-- @addSMPatch @test -->
+```
+SMP_OVERLAY=$DEMO_HOME/smp
+mkdir $SMP_OVERLAY
+cat <<EOF >$SMP_OVERLAY/kustomization.yaml
+resources:
+- ../base
+
+patchesStrategicMerge:
+- |-
+  apiVersion: apps/v1
+  kind: Deployment
+  metadata:
+    name: deploy
+  spec:
+    template:
+      spec:
+        containers:
+        - name: nginx
+          image: nginx:latest
+          
+EOF
+```
+
+Running `kustomize build $SMP_OVERLAY`, in the output confirm that image is updated successfully.
+
+<!-- @confirmSMPatch @test -->
+```
+test 1 == \
+  $(kustomize build $SMP_OVERLAY | grep "image: nginx:latest" | wc -l); \
+  echo $?
+```
+
+The output is
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: deploy
+spec:
+  template:
+    metadata:
+      labels:
+        foo: bar
+    spec:
+      containers:
+        - name: nginx
+          image: nginx:latest
+          args:
+          - one
+          - two
+```
+
+`$patch: delete` and `$patch: replace` also work in the inline patch. Change the inline patch to delete the container `nginx`.
+
+<!-- @addDeleteSMPatch @test -->
+```
+cat <<EOF >$SMP_OVERLAY/kustomization.yaml
+resources:
+- ../base
+
+patchesStrategicMerge:
+- |-
+  apiVersion: apps/v1
+  kind: Deployment
+  metadata:
+    name: deploy
+  spec:
+    template:
+      spec:
+        containers:
+        - name: nginx
+          $patch: delete
+
+EOF
+```
+Running `kustomize build $SMP_OVERLAY`, in the output confirm that the `nginx` container has been deleted.
+
+<!-- @confirmDeleteSMPatch @test -->
+```
+test 0 == \
+  $(kustomize build $SMP_OVERLAY | grep "image: nginx" | wc -l); \
+  echo $?
+```
+
+The output is
+```
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: deploy
+spec:
+  template:
+    metadata:
+      labels:
+        foo: bar
+    spec:
+      containers: []
+```
+
+## Inline Patch for PatchesJson6902
+
+Create an overlay and add an inline patch in `patchesJSON6902` field to the kustomization file
+to change the image from `nginx` to `nginx:latest`.
+
+<!-- @addJSONPatch @test -->
+```
+JSON_OVERLAY=$DEMO_HOME/json
+mkdir $JSON_OVERLAY
+cat <<EOF >$JSON_OVERLAY/kustomization.yaml
+resources:
+- ../base
+
+patchesJSON6902:
+- target:
+    group: apps
+    version: v1
+    kind: Deployment
+    name: deploy
+  patch: |-
+    - op: replace
+      path: /spec/template/spec/containers/0/image
+      value: nginx:latest
+EOF
+```
+
+Running `kustomize build $JSON_OVERLAY`, in the output confirm that image is updated successfully.
+
+<!-- @confirmJSONPatch @test -->
+```
+test 1 == \
+  $(kustomize build $JSON_OVERLAY | grep "image: nginx:latest" | wc -l); \
+  echo $?
+```
+
+The output is
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: deploy
+spec:
+  template:
+    metadata:
+      labels:
+        foo: bar
+    spec:
+      containers:
+        - name: nginx
+          image: nginx:latest
+          args:
+          - one
+          - two
+```
+
+## Inline Patch for Patches
+
+Create an overlay and add an inline patch in `patches` field to the kustomization file
+to change the image from `nginx` to `nginx:latest`.
+
+<!-- @addPatch @test -->
+```
+PATCH_OVERLAY=$DEMO_HOME/patch
+mkdir $PATCH_OVERLAY
+cat <<EOF > $PATCH_OVERLAY/kustomization.yaml
+resources:
+- ../base
+
+patches:
+- target:
+    kind: Deployment
+    name: deploy
+  patch: |-
+    apiVersion: apps/v1
+    kind: Deployment
+    metadata:
+      name: deploy
+    spec:
+      template:
+        spec:
+          containers:
+          - name: nginx
+            image: nginx:latest
+EOF
+```
+
+Running `kustomize build $PATCH_OVERLAY`, in the output confirm that image is updated successfully.
+
+<!-- @confirmPatch @test -->
+```
+test 1 == \
+  $(kustomize build $PATCH_OVERLAY | grep "image: nginx:latest" | wc -l); \
+  echo $?
+```
+
+The output is
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: deploy
+spec:
+  template:
+    metadata:
+      labels:
+        foo: bar
+    spec:
+      containers:
+        - name: nginx
+          image: nginx:latest
+          args:
+          - one
+          - two
+```