k8s之configmap应用

一、创建configmap

1、基于命令创建configmap

root@k8s-master01:~# kubectl create configmap demoapp-cfg --from-literal=listen.port=8080 --from-literal=listen.address='127.0.0.1'
configmap/demoapp-cfg created
root@k8s-master01:~# kubectl get cm
NAME               DATA   AGE
demoapp-cfg        2      7s
kube-root-ca.crt   1      35h

root@k8s-master01:~# kubectl get cm demoapp-cfg -oyaml
apiVersion: v1
data:
  listen.address: 127.0.0.1
  listen.port: "8080"
kind: ConfigMap
metadata:
  creationTimestamp: "2024-01-20T00:55:59Z"
  name: demoapp-cfg
  namespace: default
  resourceVersion: "273698"
  uid: 1df08044-46c7-4672-a328-7f81174e27d8

2、基于文件创建nginx-configmap

准备nginx配置文件

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# pwd
/root/learning-k8s/examples/configmaps_and_secrets
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# ls nginx-conf.d/
myserver-gzip.cfg  myserver-status.cfg  myserver.conf
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets#

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# ls nginx-conf.d/
myserver-gzip.cfg  myserver-status.cfg  myserver.conf
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# cat nginx-conf.d/myserver-gzip.cfg
gzip on;
gzip_comp_level 5;
gzip_proxied     expired no-cache no-store private auth;
gzip_types text/plain text/css application/xml text/javascript;
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# cat nginx-conf.d/myserver-status.cfg
location /nginx-status {
    stub_status on;
    access_log off;
}
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# cat nginx-conf.d/myserver.conf
server {
    listen 8080;
    server_name www.ik8s.io;

    include /etc/nginx/conf.d/myserver-*.cfg;

    location / {
        root /usr/share/nginx/html;
    }
}

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl create configmap nginx-cfg --from-file=./nginx-conf.d/myserver.conf  --from-file=./nginx-conf.d/myserver-status.cfg --from-file=./nginx-conf.d/myserver-gzip.cfg --dry-run=client -oyaml
apiVersion: v1
data:
  myserver-gzip.cfg: |
    gzip on;
    gzip_comp_level 5;
    gzip_proxied     expired no-cache no-store private auth;
    gzip_types text/plain text/css application/xml text/javascript;
  myserver-status.cfg: |
    location /nginx-status {
        stub_status on;
        access_log off;
    }
  myserver.conf: |
    server {
        listen 8080;
        server_name www.ik8s.io;

        include /etc/nginx/conf.d/myserver-*.cfg;

        location / {
            root /usr/share/nginx/html;
        }
    }
kind: ConfigMap
metadata:
  creationTimestamp: null
  name: nginx-cfg

以下命令同上命令效果相同

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl create configmap nginx-cfg --from-file=./nginx-conf.d/ --dry-run=client -oyaml
apiVersion: v1
data:
  myserver-gzip.cfg: |
    gzip on;
    gzip_comp_level 5;
    gzip_proxied     expired no-cache no-store private auth;
    gzip_types text/plain text/css application/xml text/javascript;
  myserver-status.cfg: |
    location /nginx-status {
        stub_status on;
        access_log off;
    }
  myserver.conf: |
    server {
        listen 8080;
        server_name www.ik8s.io;

        include /etc/nginx/conf.d/myserver-*.cfg;

        location / {
            root /usr/share/nginx/html;
        }
    }
kind: ConfigMap
metadata:
  creationTimestamp: null
  name: nginx-cfg

二、在Pod上引用环境变量

• 环境变量
  
  将configmap对象上的某key的值赋值给(valueFrom)指定的环境变量

• 卷
  
  在Pod上基于configMap卷插件引用configmap对象
  
  在Container上挂载configMap卷
  
  每个kv会分别被映射为一个文件，文件名同key，value将成为文件内容

  注意：

  • 通过环境变量引用在Pod创建的时候完成赋值，configmap更改不生效。
  • 通过卷挂载，基于卷引用，configmap可以动态加载。

1、通过环境变量引用configmap

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# cat configmaps-env-demo.yaml
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: demoapp-config
  namespace: default
data:
  demoapp.port: "8080"
  demoapp.host: 127.0.0.1
---
apiVersion: v1
kind: Pod
metadata:
  name: configmaps-env-demo
  namespace: default
spec:
  containers:
  - image: ikubernetes/demoapp:v1.0
    name: demoapp
    env:
    - name: PORT
      valueFrom:
        configMapKeyRef:
          name: demoapp-config
          key: demoapp.port
          optional: false
    - name: HOST
      valueFrom:
        configMapKeyRef:
          name: demoapp-config
          key: demoapp.host
          optional: true

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl apply -f configmaps-env-demo.yaml
configmap/demoapp-config created
pod/configmaps-env-demo created
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl get cm
NAME               DATA   AGE
demoapp-cfg        2      24m
demoapp-config     2      6s
kube-root-ca.crt   1      35h
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl get pod
NAME                  READY   STATUS    RESTARTS   AGE
configmaps-env-demo   1/1     Running   0          7m27s

2、通过卷挂载configmap

• 创建configmap

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl create configmap nginx-config-files --from-file=./nginx-conf.d/
configmap/nginx-config-files created
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl get cm
NAME                 DATA   AGE
demoapp-cfg          2      38m
demoapp-config       2      13m
kube-root-ca.crt     1      36h
nginx-config-files   3      6s

• 创建nginx pod将configmap作为配置文件挂载到指定目录下

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# cat configmaps-volume-demo.yaml
apiVersion: v1
kind: Pod
metadata:
  name: configmaps-volume-demo
  namespace: default
spec:
  containers:
  - image: nginx:1.22
    name: nginx-server
    volumeMounts:
    - name: ngxconfs
      mountPath: /etc/nginx/conf.d/
      readOnly: true
  volumes:
  - name: ngxconfs
    configMap:
      name: nginx-config-files
      optional: false

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl apply -f configmaps-volume-demo.yaml
pod/configmaps-volume-demo created
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl get pod
NAME                     READY   STATUS    RESTARTS   AGE
configmaps-env-demo      1/1     Running   0          23m
configmaps-volume-demo   1/1     Running   0          5m16s

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl exec -it configmaps-volume-demo bash
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
root@configmaps-volume-demo:/# ls /etc/nginx/conf.d/
myserver-gzip.cfg  myserver-status.cfg  myserver.conf
root@configmaps-volume-demo:/# nginx -T
...
# configuration file /etc/nginx/conf.d/myserver.conf:
server {
    listen 8080;
    server_name www.ik8s.io;

    include /etc/nginx/conf.d/myserver-*.cfg;

    location / {
        root /usr/share/nginx/html;
    }
}

# configuration file /etc/nginx/conf.d/myserver-gzip.cfg:
gzip on;
gzip_comp_level 5;
gzip_proxied     expired no-cache no-store private auth;
gzip_types text/plain text/css application/xml text/javascript;

# configuration file /etc/nginx/conf.d/myserver-status.cfg:
location /nginx-status {
    stub_status on;
    access_log off;
}
...

• 访问nginx服务

root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# kubectl get pod -o wide
NAME                     READY   STATUS    RESTARTS   AGE   IP            NODE         NOMINATED NODE   READINESS GATES
configmaps-env-demo      1/1     Running   0          28m   10.244.2.24   k8s-node01   <none>           <none>
configmaps-volume-demo   1/1     Running   0          10m   10.244.2.25   k8s-node01   <none>           <none>
root@k8s-master01:~/learning-k8s/examples/configmaps_and_secrets# curl 10.244.2.25:8080
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>