Pod Environment Variables

spec.containers.env

• https://kubernetes.io/docs/tasks/inject-data-application/define-interdependent-environment-variables/

spec:
  containers:
    - env:
        - name: SERVICE_PORT
          value: "8080"
        - name: SERVICE_IP
          value: "172.16.1.2"
        - name: UNCHANGED_REFERENCE
          # SCHEME이 다음에 정의되어 있으므로 `$(SCHEME)://172.16.1.2:8080` 로 설정됨
          value: "$(SCHEME)://$(SERVICE_IP):$(SERVICE_PORT)"
        - name: SCHEME
          value: "https"
        - name: SERVICE_ADDRESS
          # 관련 변수가 이전에 정의도어 있으므로 `https://172.16.1.2:8080`로 설정됨
          value: "$(SCHEME)://$(SERVICE_IP):$(SERVICE_PORT)"
        - name: ESCAPED_REFERENCE
          # SCHEME이 escape되어 있으므로 `$(SCHEME)://172.16.1.2:8080`로 설정됨
          value: "$$(SCHEME)://$(SERVICE_IP):$(SERVICE_PORT)"

spec.containers.envFrom

• ConfigMap
• Secret

Pod fields to env

• https://kubernetes.io/docs/concepts/workloads/pods/downward-api/#downwardapi-fieldRef

apiVersion: v1
kind: Pod
metadata:
  name: <podName>
spec:
  containers:
    - env:
        - name: <envName>
          valueFrom:
            fieldRef:
              fieldPath: <fieldPath>
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name

• <fieldPath>
  • metadata.name
  • metadata.namespace
  • metadata.uid
  • metadata.anonotations[<key>]
  • metadata.labels[<key>]
  • spec.serviceAccountName
  • spec.nodeName
  • status.hostIP
  • status.podIP

Container fields to env

• https://kubernetes.io/docs/concepts/workloads/pods/downward-api/#downwardapi-resourceFieldRef

apiVersion: v1
kind: Pod
metadata:
  name: <podName>
spec:
  containers:
    - name: <containerName>
      env:
        - name: <envName>
          valueFrom:
            resourceFieldRef:
              # containerName: <containerName>
              resource: <resource>
        - name: CONTAINER_CPU_LIMIT
          valueFrom:
            resourceFieldRef:
              resource: limits.cpu

• <resource>
  • requests.cpu
  • requests.memory
  • requests.hugepages-*
  • requests.ephemeral-storage
  • limits.cpu
  • limits.memory
  • limits.hugepages-*
  • limits.ephemeral-storage

• CPU, Memory 설정이 없으면 kubelet이 할당가능한 최대 할당 가능 값을 사용하게 됩니다
• CPU는 올림된 Core 수가 사용됩니다(250m -> 1)
• Memory는 바이트 단위 값이 사용됩니다(64Mi -> 67108864)