apiVersion: apps/v1
kind: Deployment
metadata:
  name: app
  labels:
    app: app
spec:
  selector:
    matchLabels:
      app: app
  template:
    metadata:
      labels:
        app: app
    spec:
      nodeSelector:
        beta.kubernetes.io/os: linux
      containers:
      - name: app
        image: app:dev
        imagePullPolicy: "Always"
        ports:
        - name: app
          containerPort: 80
          protocol: TCP
        - name: smtp
          containerPort: 
          protocol: TCP

Error: Failed to render chart: exit status 1: Error: unable to build kubernetes objects from release manifest: error validating "": error validating data: ValidationError(Deployment.spec.template.spec.containers[0].ports[1]): missing required field "containerPort" in io.k8s.api.core.v1.ContainerPort