是否可以在 json 或 yaml 中获取一个 kubernetes 对象，并将所有可选字段显式设置为 null？

Question

我正在尝试将 helm/kubernetes 代码库迁移到 dhall-kubernetes. Dhall is typed, so I need to provide full records with optional fields set to null if there were not set. So I'm looking for something like kubectl get objname id -o yaml, but I need it to output all optional fields like fieldName: null. Is there a way to accomplish this? I don't know how to do it, so as a plan B I wrote dhall-default，我尝试以不同的方式处理它。

Answer 1

我会将@sjakobi 的解决方案变成@dredozubov 建议的答案

您可以将所需的类型从 dhall-kubernetes 传递到 yaml-to-dhall，它会生成等效的 Dhall 代码，尽管没有任何简化。

例如，假设您有以下 Kubernetes 资源：

# ./nginx.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      name: nginx
  template:
    metadata:
      name: nginx
    spec:
      containers:
        - image: nginx:1.15.3
          name: nginx
          ports:
            - containerPort: 80

...以及以下用于 Kubernetes 部署的 Dhall 类型：

-- ./Deployment.dhall

let kubernetes = https://raw.githubusercontent.com/dhall-lang/dhall-kubernetes/506d633e382872346927b8cb9884d8b7382e6cab/package.dhall

in  kubernetes.Deployment.Type

然后你可以通过运行将YAML翻译成Dhall:

$ yaml-to-dhall --file ./nginx.yaml ./Deployment.dhall

输出有点大（~1300 行），因为 yaml-to-dhall 还没有利用对默认值的支持，所以我不会在这里包含输出。

如果将结果通过管道返回 dhall-to-yaml，那么您将获得原始资源（尽管字段已排序）：

$ yaml-to-dhall --file ./nginx.yaml ./Deployment.dhall | dhall-to-yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      name: nginx
  template:
    metadata:
      name: nginx
    spec:
      containers:
        - image: nginx:1.15.3
          name: nginx
          ports:
            - containerPort: 80

... 如果您向 dhall-to-yaml 提供 --preserve-null 选项，它将保留所有 null 字段作为问题请求：

$ yaml-to-dhall --file ./nginx.yaml ./Deployment.dhall | dhall-to-yaml --preserve-null 
apiVersion: apps/v1
kind: Deployment
metadata:
  annotations: null
  clusterName: null
  creationTimestamp: null
  deletionGracePeriodSeconds: null
  deletionTimestamp: null
  finalizers: null
  generateName: null
  generation: null
  labels: null
  managedFields: null
  name: nginx
  namespace: null
  ownerReferences: null
  resourceVersion: null
  selfLink: null
  uid: null
spec:
  minReadySeconds: null
  paused: null
  progressDeadlineSeconds: null
  replicas: 2
  revisionHistoryLimit: null
  selector:
    matchExpressions: null
    matchLabels:
      name: nginx
  strategy: null
  template:
    metadata:
      annotations: null
      clusterName: null
      creationTimestamp: null
      deletionGracePeriodSeconds: null
      deletionTimestamp: null
      finalizers: null
      generateName: null
      generation: null
      labels: null
      managedFields: null
      name: nginx
      namespace: null
      ownerReferences: null
      resourceVersion: null
      selfLink: null
      uid: null
    spec:
      activeDeadlineSeconds: null
      affinity: null
      automountServiceAccountToken: null
      containers:
        - args: null
          command: null
          env: null
          envFrom: null
          image: nginx:1.15.3
          imagePullPolicy: null
          lifecycle: null
          livenessProbe: null
          name: nginx
          ports:
            - containerPort: 80
              hostIP: null
              hostPort: null
              name: null
              protocol: null
          readinessProbe: null
          resources: null
          securityContext: null
          startupProbe: null
          stdin: null
          stdinOnce: null
          terminationMessagePath: null
          terminationMessagePolicy: null
          tty: null
          volumeDevices: null
          volumeMounts: null
          workingDir: null
      dnsConfig: null
      dnsPolicy: null
      enableServiceLinks: null
      ephemeralContainers: null
      hostAliases: null
      hostIPC: null
      hostNetwork: null
      hostPID: null
      hostname: null
      imagePullSecrets: null
      initContainers: null
      nodeName: null
      nodeSelector: null
      overhead: null
      preemptionPolicy: null
      priority: null
      priorityClassName: null
      readinessGates: null
      restartPolicy: null
      runtimeClassName: null
      schedulerName: null
      securityContext: null
      serviceAccount: null
      serviceAccountName: null
      shareProcessNamespace: null
      subdomain: null
      terminationGracePeriodSeconds: null
      tolerations: null
      topologySpreadConstraints: null
      volumes: null
status: null

是否可以在 json 或 yaml 中获取一个 kubernetes 对象，并将所有可选字段显式设置为 null？

Is it possible to get a kubernetes object in json or yaml with all optional fields explicitly set to null?

kubernetes

dhall