ConfigMap 是一種 API 物件，用來將非機密性的資料儲存到鍵值對中。使用時， Pods 可以將其用作環境變數、命令列引數或者儲存卷中的配置檔案。

以下以nginx映象提供配置檔案為例映象演示,是將ConfigMap 以卷的形式掛載到Pod中

1.編寫congfigmap, serice,Deployment yaml檔案

root@k8-deploy:~/k8s-yaml/volume# vim configmap.yml 
apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config
data:
 default: |
    server {
       listen       80;
       server_name  www.yanql.com;
       index        index.html;

       location / {
           root /data/nginx/html;
           if (!-e $request_filename) {
               rewrite ^/(.*) /index.html last;
           }
       }
    }


---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: ng-deploy-80
  template:
    metadata:
      labels:
        app: ng-deploy-80
    spec:
      containers:
      - name: ng-deploy-80
        image: nginx:1.17.10
        ports:
        - containerPort: 80
        volumeMounts:
        - mountPath: /data/nginx/html
          name: nginx-static-dir
        - name: nginx-config
          mountPath:  /etc/nginx/conf.d
      volumes:
      - name: nginx-static-dir
        hostPath:
          path: /data/nginx/html
      - name: nginx-config
        configMap:
          name: nginx-config
          items:
             - key: default
               path: www.yanql.com.conf

---
apiVersion: v1
kind: Service
metadata:
  name: ng-deploy-80
spec:
  ports:
  - name: http
    port: 81
    targetPort: 80
    nodePort: 30080
    protocol: TCP
  type: NodePort
  selector:
    app: ng-deploy-80
 

2.使用yaml檔案建立資源

root@k8-deploy:~/k8s-yaml/volume# kubectl apply -f configmap.yml 
configmap/nginx-config created
deployment.apps/nginx-deployment created
service/ng-deploy-80 created

3.檢視資源是否建立完成

root@k8-deploy:~/k8s-yaml/volume# kubectl get configmap
NAME               DATA   AGE
kube-root-ca.crt   1      26d
nginx-config       1      89s

root@k8-deploy:~/k8s-yaml/volume# kubectl get svc
NAME           TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
kubernetes     ClusterIP   10.0.0.1     <none>        443/TCP        26d
ng-deploy-80   NodePort    10.0.41.43   <none>        81:30080/TCP   97s

root@k8-deploy:~/k8s-yaml/volume# kubectl get deploy
NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   1/1     1            1           105s
 

4.驗證配置檔案在pod中是否掛載了configmap提供的配置檔案

root@k8-deploy:~/k8s-yaml/volume# kubectl get pod
NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-55cb7cdfff-gkdcf   1/1     Running   0          14m

root@k8-deploy:~/k8s-yaml/volume# kubectl exec nginx-deployment-55cb7cdfff-gkdcf -it -- bash

root@nginx-deployment-55cb7cdfff-gkdcf:/# cat /etc/nginx/conf.d/www.yanql.com.conf 
server {
   listen       80;
   server_name  www.yanql.com;
   index        index.html;

   location / {
       root /data/nginx/html;
       if (!-e $request_filename) {
           rewrite ^/(.*) /index.html last;
       }
   }
}
 

5.通過訪問serice的nodePort埠驗證nginx服務是否正常()

# 3個node節點
root@k8-deploy:~/k8s-yaml/volume# curl 192.168.2.17:30080
www.yanql.com Mon Oct 11 03:31:35 UTC 2021

root@k8-deploy:~/k8s-yaml/volume# curl 192.168.2.18:30080
www.yanql.com Mon Oct 11 03:31:35 UTC 2021

root@k8-deploy:~/k8s-yaml/volume# curl 192.168.2.19:30080
www.yanql.com Mon Oct 11 03:31:35 UTC 2021

6.動態修改configmap中配置檔案,pod中掛載的配置檔案會同步修改。

# 找到需要修改的configmap
root@k8-deploy:~/k8s-yaml/volume# kubectl get configmap
NAME               DATA   AGE
kube-root-ca.crt   1      26d
nginx-config       1      31m

# 修改configmap
root@k8-deploy:~/k8s-yaml/volume# kubectl edit configmap nginx-config

configmap也可以使用create建立，使用--from-file指定配置檔案的內容。

詳情參考官網文件：https://kubernetes.io/zh/docs/tasks/configure-pod-container/configure-pod-configmap/

可以以使用 kubectl create configmap 命令基於 目錄、檔案 或者字面值來建立 ConfigMap

kubectl create configmap <map-name> <data-source>

基於目錄建立 ConfigMap

# 建立本地目錄
mkdir -p configure-pod-container/configmap/

# 將例項檔案下載到 `configure-pod-container/configmap/` 目錄
wget https://kubernetes.io/examples/configmap/game.properties -O configure-pod-container/configmap/game.properties
wget https://kubernetes.io/examples/configmap/ui.properties -O configure-pod-container/configmap/ui.properties

# 建立 configmap
kubectl create configmap game-config --from-file=configure-pod-container/configmap/

可以使用下面的命令顯示 ConfigMap 的詳細資訊

kubectl describe configmaps game-config

基於單個檔案或多個檔案建立 ConfigMap

kubectl create configmap game-config-2 --from-file=configure-pod-container/configmap/game.properties

kubectl create configmap game-config-2 --from-file=configure-pod-container/configmap/game.properties --from-file=configure-pod-container/configmap/ui.properties

將configmap匯出到yaml

kubectl get configmap config-multi-env-files -o yaml

定義從檔案建立 ConfigMap 時要使用的鍵

kubectl create configmap game-config-3 --from-file=<my-key-name>=<path-to-file>