可以通过单个ConfigMap定义环境变量，也通过多个ConfigMap定义环境变量和将ConfigMap作为卷挂载成文件使用等。valueFrom通常用于使用ConfigMap的单个Key设置环境变量，但实际使用时更常用的是把ConfigMap里面所有的数据都作为环境变量，此时可以使用envFrom参数。

一、使用valueFrom定义单个环境变量¶

1.创建工作目录

[root@k8s-master01 ~]# mkdir -p configmap/conf

2.编写配置文件

[root@k8s-master01 ~]# vim configmap/conf/game.conf
lives=3
secret.code=true

3.创建ConfigMap

[root@k8s-master01 conf]# kubectl create cm gameenvcm --from-env-file=/root/configmap/conf/game.conf

4.验证

[root@k8s-master01 conf]# kubectl get cm 
NAME               DATA   AGE
cmfromdir          2      25m
cmfromfile         1      20m
cmspecialname      1      10m
cmspecialname2     2      7m51s
gameenvcm          2      11s
kube-root-ca.crt   1      26h

[root@k8s-master01 conf]# kubectl get cm gameenvcm -oyaml
apiVersion: v1
data:
  lives: "3"
  secret.code: "true"
kind: ConfigMap
metadata:
  creationTimestamp: "2022-12-03T08:39:30Z"
  name: gameenvcm
  namespace: default
  resourceVersion: "36100"
  uid: 62346419-855c-48de-8f78-9b17bb5da665

[root@k8s-master01 ~]# kubectl describe cm gameenvcm 
Name:         gameenvcm
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
lives:
----
3
secret.code:
----
true

BinaryData
====

Events:  <none>

5.编写一个deployment的Yaml文件

[root@k8s-master01 conf]# vim dp-cm.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: dp-cm
  name: dp-cm
spec:
  replicas: 1
  selector:
    matchLabels:
      app: dp-cm
  template:
    metadata:
      labels:
        app: dp-cm
    spec:
      containers:
      - image: registry.cn-hangzhou.aliyuncs.com/zq-demo/nginx:1.14.2
        name: nginx
        env: 
        - name: TEST_ENV
          value: testenv
        - name: LIVES
          valueFrom:
            configMapKeyRef: 
              name: gameenvcm
              key: lives

上面内容分析

    env: 
    #手动创建
    - name: TEST_ENV
      value: testenv
    #基于valueFrom单个定义环境变量
    - name: LIVES
      valueFrom:
        configMapKeyRef: 
          name: gameenvcm
          key: lives

6.创建一个deployment

[root@k8s-master01 conf]# kubectl create -f dp-cm.yaml 
deployment.apps/dp-cm created

注意:创建的deployment要和configMap位于同一命名空间，且名为gameenvcm的configMap要真实存在，否则Pod起不来

7.验证

[root@k8s-master01 conf]# kubectl get deployments
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
dp-cm              1/1     1            1           27s

[root@k8s-master01 conf]# kubectl get po
NAME                               READY   STATUS    RESTARTS      AGE
dp-cm-6d84dc5fcb-vzrfw             1/1     Running   0             82s

8.查看env

[root@k8s-master01 conf]# kubectl exec dp-cm-6d84dc5fcb-vzrfw -- env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=dp-cm-6d84dc5fcb-vzrfw
NGINX_VERSION=1.14.2
NJS_VERSION=0.5.0
PKG_RELEASE=1~buster
TEST_ENV=testenv
LIVES=3
KUBERNETES_PORT_443_TCP=tcp://10.0.0.1:443
NGINX_PORT=tcp://10.0.239.136:80
NGINX_PORT_80_TCP_PORT=80
KUBERNETES_SERVICE_HOST=10.0.0.1
KUBERNETES_PORT=tcp://10.0.0.1:443
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_PORT_443_TCP_PORT=443
KUBERNETES_PORT_443_TCP_ADDR=10.0.0.1
NGINX_SERVICE_HOST=10.0.239.136
NGINX_PORT_80_TCP=tcp://10.0.239.136:80
KUBERNETES_SERVICE_PORT=443
KUBERNETES_SERVICE_PORT_HTTPS=443
NGINX_SERVICE_PORT=80
NGINX_PORT_80_TCP_PROTO=tcp
NGINX_PORT_80_TCP_ADDR=10.0.239.136
HOME=/root

二、使用envFrom定义多个环境变量¶