k8s

How to valid your K8S manifest file

kubectk apply / create with --dry-run option, you can check whether manifest file is correctly or not without without persisting the resource into your cluster.
--dry-run has three options: none, server, client. I will try to run with these options.

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apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      name: nginx
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        # Correct: - containerPort: 80
        - containerPort: -1
          name: nginx
        resources:
          limits:
            memory: "128Mi"
            cpu: "500m"

  • dry-run: none (default)

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    sh-3.2$ kubectl apply -f nginx-deployment.yaml --dry-run=none
    The Deployment "nginx" is invalid: spec.template.spec.containers[0].ports[0].containerPort: Invalid value: -1: must be between 1 and 65535, inclusive

  • dry-run: client

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    sh-3.2$ kubectl apply -f nginx-deployment.yaml --dry-run=client
    deployment.apps/nginx created (dry run)

    If client strategy, only print the object that would be sent, without sending it.
    So you don’t know the syntax of manifest file is correct or not.

  • dry-run: server

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    sh-3.2$ kubectl apply -f nginx-deployment.yaml --dry-run=server
    The Deployment "nginx" is invalid: spec.template.spec.containers[0].ports[0].containerPort: Invalid value: -1: must be between 1 and 65535, inclusive

    If server strategy, submit server-side request without persisting the resource.
    The syntax of manifest file will be checked.