inlinePatch.md

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.

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.

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.

test 1 == \
  $(kustomize build $SMP_OVERLAY | grep "image: nginx:latest" | wc -l); \
  echo $?

The output is

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.

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.

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.

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.

test 1 == \
  $(kustomize build $JSON_OVERLAY | grep "image: nginx:latest" | wc -l); \
  echo $?

The output is

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.

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.

test 1 == \
  $(kustomize build $PATCH_OVERLAY | grep "image: nginx:latest" | wc -l); \
  echo $?

The output is

apiVersion: apps/v1
kind: Deployment
metadata:
  name: deploy
spec:
  template:
    metadata:
      labels:
        foo: bar
    spec:
      containers:
        - name: nginx
          image: nginx:latest
          args:
          - one
          - two