kustomize patching a specific container other than by array (/containers/0)

user_8436666 0
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I'm trying to see if there's a way to apply a kustomize patchTransformer to a specific container in a pod other than using its array index. For example, if I have 3 containers in a pod, (0, 1, 2) and I want to patch container "1" I would normally do something like this:

patch: |-
  - op: add
    path: /spec/containers/1/command
    value:  ["sh", "-c", "tail -f /dev/null"]

That is heavily dependent on that container order remaining static. If container "1" is removed for whatever reason, the array is reshuffled and container "2" suddenly becomes container "1", making my patch no longer applicable.

Is there a way to patch by name, or target a label/annotation, or some other mechanism?

path: /spec/containers/${NAME_OF_CONTAINER}/command

Any insight is greatly appreciated.

kustomize kubernetes patch containers arrays
1 Answers

This is more of a Json6902 patch limitation together with the fact that containers are defined in a K8s pod as an Array and not a Hash where something like this would work:

path: /spec/containers/${NAME_OF_CONTAINER}/command

You could just try a StrategicMergePatch. which essentially what kubectl apply does.

cat <<EOF > deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  selector:
    matchLabels:
      run: my-app
  replicas: 2
  template:
    metadata:
      labels:
        run: my-app
    spec:
      containers:
      - name: my-container
        image: myimage
        ports:
        - containerPort: 80
EOF

cat <<EOF > set_command.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  template:
    spec:
      containers:
      - name: my-app
        command: ["sh", "-c", "tail -f /dev/null"]
EOF

cat <<EOF >./kustomization.yaml
resources:
- deployment.yaml
patchesStrategicMerge:
- set_command.yaml
EOF

✌️

user_29892610
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