如何在 Kubernetes Pod 中注入环境变量及优先级问题

apiVersion: v1
kind: Pod
metadata:
  name: envar-demo
  labels:
    purpose: demonstrate-envars
spec:
  containers:
  - name: envar-demo-container
    image: gcr.io/google-samples/node-hello:1.0
    env:
    - name: DEMO_GREETING
      value: "Hello from the environment"
    - name: DEMO_FAREWELL
      value: "Such a sweet sorrow"
    - name: MY_NODE_NAME
      valueFrom:
        fieldRef:
          fieldPath: spec.nodeName
    - name: MY_POD_NAME
      valueFrom:
        fieldRef:
          fieldPath: metadata.name

apiVersion: v1
kind: Pod
metadata:
  name: secret-env-pod
spec:
  containers:
  - name: mycontainer
    image: redis
    envFrom:
      - secretRef:
          name: secret-config
    env:
      - name: SECRET_USERNAME
        valueFrom:
          secretKeyRef:
            name: secret-config
            key: username
      - name: SECRET_PASSWORD
        valueFrom:
          secretKeyRef:
            name: secret-config
            key: password

apiVersion: v1
kind: Pod
metadata:
  name: dapi-test-pod
spec:
  containers:
    - name: test-container
      image: k8s.gcr.io/busybox
      envFrom:
        - configMapRef:
            name: configmap-config
      env:
        - name: SPECIAL_LEVEL_KEY
          valueFrom:
            configMapKeyRef:
              name: special-config
              key: special.how
        - name: LOG_LEVEL
          valueFrom:
            configMapKeyRef:
              name: env-config
              key: log_level