在k8s中通常会有需要向容器传递变量参数，可以通过env或envFrom配置容器环境变量。

🐳 Docker传参方式

先看看docker如何传参，假设docker启动参数如下：

docker run -e PARAMS="--spring.datasource.url=jdbc:mysql://127.0.0.1:3306/db_test?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=Asia/Shanghai"

上述传递的参数名为：PARAMS

⚙️ k8s通过env配置环境变量

spec:
  template:
    spec:
      containers:
        - name: xx-name
          env:
            - name: PARAMS
              value: "--spring.datasource.url=jdbc:mysql://127.0.0.1:3306/db_test?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=Asia/Shanghai"

📝 k8s通过envFrom访问configMap配置环境变量

spec:
  template:
    spec:
      containers:
        - name: xx-name
          envFrom:
            - configMapRef:
                name: xx-env-configmap

xx-env-configmap为对应的configMap，configMap配置如下：

apiVersion: v1
kind: ConfigMap
metadata:
  name: xx-env-configmap
data:
  PARAMS: --spring.datasource.url=jdbc:mysql://127.0.0.1:3306/db_xx?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=Asia/Shanghai --server.servlet.context-path=/

上述配置一个key为PARAMS的参数变量，值以空格隔开，但不太直观，不太方便配置，可以采用以下这种形式：

apiVersion: v1
kind: ConfigMap
metadata:
  name: xx-env-configmap
data:
  PARAMS: >-
    --spring.datasource.url=jdbc:mysql://127.0.0.1:3306/db_xx?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=Asia/Shanghai
    --server.servlet.context-path=/

🔗 k8s通过env访问configMap配置环境变量

spec:
  template:
    spec:
      containers:
        - name: xx-name
          env:
            - name: PARAMS
              valueFrom:
                configMapKeyRef:
                  name: xx-env-configmap
                  key: PARAMS