在容器中通过环境变量获取Pod基础信息

客户如果需要在容器内获取POD的基础信息，可以通过kubernetes中的Downward API注入环境变量的方式实现。本操作实践展示如何在Deployment和POD的定义中增加环境变量配置，获取Pod的namespace、name、uid、IP、Region和AZ。

CCI创建Pod并分配节点的同时，Pod Annotations中新增所在节点的region和az信息。

此时Pod中Annotations格式为：

apiVersion: v1
 kind: Pod
 metadata:
   annotations:
     topology.kubernetes.io/region: "{{region}}"  
     topology.kubernetes.io/zone: "{{available-zone}}"

topology.kubernetes.io/region为所在节点的region信息。

topology.kubernetes.io/zone为所在节点的az信息。

kind: Deployment
apiVersion: apps/v1
metadata:
  name: cci-downwardapi-test
  namespace: cci-test  # 填写具体的命名空间
spec:
  replicas: 2
  selector:
    matchLabels:
      app: cci-downwardapi-test
  template:
    metadata:
      labels:
        app: cci-downwardapi-test
    spec:
      containers:
        - name: container-0
          image: 'library/euleros:latest'
          command:
            - /bin/bash
            - '-c'
            - while true; do echo hello; sleep 10; done
          env:
           - name: MY_POD_UID
             valueFrom:
               fieldRef:
                 fieldPath: metadata.uid
           - name: MY_POD_NAME
             valueFrom:
               fieldRef:
                 fieldPath: metadata.name
           - name: MY_POD_NAMESPACE
             valueFrom:
               fieldRef:
                 fieldPath: metadata.namespace
           - name: MY_POD_IP
             valueFrom:
               fieldRef:
                 fieldPath: status.podIP
           - name: REGION
             valueFrom:
               fieldRef:       
                 fieldPath: metadata.annotations['topology.kubernetes.io/region']
           - name: ZONE
             valueFrom:
               fieldRef:
                 fieldPath: metadata.annotations['topology.kubernetes.io/zone']
          resources:
            limits:
              cpu: 500m
              memory: 1Gi
            requests:
              cpu: 500m
              memory: 1Gi

负载运行起来后就可以通过环境变量在容器内查看到具体的Pod信息：

图1 Pod基础信息