kubernetes(16)：k8s的配置管理configmap

K8s的配置管理configmap

1 k8s中的配置修改需求

很多情况下我们为某一应用做好镜像，当我们想修改其中的一些参数的时候，就变得比较麻烦，又要重新制作镜像，我们是不是有一种方式，让镜像根据不同的场景调用我们不同的配置文件呢，那我们就需要用到 k8s 的另外一种资源，那就是 ConfigMap。

我们知道，在几乎所有的应用开发中，都会涉及到配置文件的变更，比如说在web的程序中，需要连接数据库，缓存甚至是队列等等。而我们的一个应用程序从写第一行代码开始，要经历开发环境、测试环境、预发布环境只到最终的线上环境。而每一个环境都要定义其独立的各种配置。如果我们不能很好的管理这些配置文件，你的运维工作将顿时变的无比的繁琐。为此业内的一些大公司专门开发了自己的一套配置管理中心，如360的Qcon，百度的disconf等。kubernetes也提供了自己的一套方案，即ConfigMap。kubernetes通过ConfigMap来实现对容器中应用的配置管理。

给Kubernetes管理员或用户提供从集群外部向POD内部的应用注入配置信息的方式.类似一个配置中心。把配置文件存入配置中心。配置有变化，让POD重载这些配置文件，极大方便管理。可以理解为configMap就是K8S上的配置中心。但是configMap存储的数据是明文保存的，Secret则是BASE64编码机制保存的。

2 创建 ConfigMap的4个方法

ConfigMap是用来存储配置文件的kubernetes资源对象，所有的配置内容都存储在etcd中。

创建ConfigMap的方式有4种：

l 通过直接在命令行中指定configmap参数创建，即--from-literal；

l 通过指定文件创建，即将一个配置文件创建为一个ConfigMap，--from-file=<文件>；

l 通过一个文件内多个键值对，--from-env-file=<文件>；

l 事先写好标准的configmap的yaml文件，然后kubectl create -f 创建。

2.1 通过--from-literal

kubectl create configmap test-config --from-literal=db.host=192.168.1.2 --from-literal=db.port=3306  --from-literal=user=admin --from-literal=password=123456

[root@k8s-master configmap]# kubectl get cm test-config
NAME          DATA   AGE
test-config   4      18s
[root@k8s-master configmap]# kubectl get cm test-config -o yaml
apiVersion: v1
data:
  db.host: 192.168.1.2
  db.port: "3306"
  password: "123456"
  user: admin
kind: ConfigMap
metadata:
  creationTimestamp: "2019-09-03T08:38:54Z"
  name: test-config
  namespace: default
  resourceVersion: "680690"
  selfLink: /api/v1/namespaces/default/configmaps/test-config
  uid: fc3ef6c3-6b97-4b73-8692-9db6f175659d
[root@k8s-master configmap]#

2.2 通过--from-file

echo -n '192.168.0.1' > ./db.host
echo -n '3306' > ./db.port
echo -n 'admin' > ./user
echo -n '123456' > ./password
kubectl create cm test-config2 --from-file=./db.host --from-file=./db.port --from-file=user --from-file=password

[root@k8s-master configmap]# kubectl get cm test-config2NAME           DATA   AGE
test-config2   4      6s
[root@k8s-master configmap]# kubectl get cm test-config2 -o yamlapiVersion: v1
data:
  db.host: 192.168.0.1
  db.port: "3306"
  password: "123456"
  user: admin
kind: ConfigMap
metadata:
  creationTimestamp: "2019-09-03T08:42:46Z"
  name: test-config2
  namespace: default
  resourceVersion: "681058"
  selfLink: /api/v1/namespaces/default/configmaps/test-config2
  uid: 9176b7e2-0ac5-4891-9040-5bb8b3e1450c
[root@k8s-master configmap]#

2.3 通过--from-env-file

cat << EOF > env-config.txt
db.host=192.168.0.1
db.port=3306
user=admin
password=123456
EOF
kubectl create cm test-config3 --from-env-file=env-config.txt

[root@k8s-master configmap]# kubectl get cm test-config3NAME           DATA   AGE
test-config3   4      5s
[root@k8s-master configmap]# kubectl get cm test-config3 -o yamlapiVersion: v1
data:
  db.host: 192.168.0.1
  db.port: "3306"
  password: "123456"
  user: admin
kind: ConfigMap
metadata:
  creationTimestamp: "2019-09-03T08:46:02Z"
  name: test-config3
  namespace: default
  resourceVersion: "681371"
  selfLink: /api/v1/namespaces/default/configmaps/test-config3
  uid: 882cd303-9d94-4f04-bc10-2cd205293df3
[root@k8s-master configmap]#

2.4 通过yaml文件

# cat config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: test-config4
data:
  db.host: 192.168.0.200
  db.port: "3306"
  user: "admin"
  password: "123456"

[root@k8s-master configmap]# kubectl apply -f config.yaml
configmap/test-config4 created
[root@k8s-master configmap]# kubectl get cm test-config4
NAME           DATA   AGE
test-config4   4      4s
[root@k8s-master configmap]# kubectl get cm test-config4 -o yaml
apiVersion: v1
data:
  db.host: 192.168.0.200
  db.port: "3306"
  password: "123456"
  user: admin
kind: ConfigMap
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","data":{"db.host":"192.168.0.200","db.port":"3306","password":"123456","user":"admin"},"kind":"ConfigMap","metadata":{"annotations":{},"name":"test-config4","namespace":"default"}}
  creationTimestamp: "2019-09-03T08:48:31Z"
  name: test-config4
  namespace: default
  resourceVersion: "681609"
  selfLink: /api/v1/namespaces/default/configmaps/test-config4
  uid: 3101d4c0-e130-46da-8b18-8bf0116b11f1
[root@k8s-master configmap]#

3 ConfigMap 使用

使用ConfigMap有二种方式：

l 第一种是通过环境变量的方式，直接传递给pod；

l 第二种是作为volume的方式挂载到pod内。

3.1 Nginx通过环境变量使用

使用valueFrom、configMapKeyRef、name、key指定要用的key。

https://www.cnblogs.com/lovelinux199075/p/11294987.html

docker官方给出的Nginx安装文档

https://github.com/docker-library/docs/tree/master/nginx#using-environment-variables-in-nginx-configuration

常见的变量

- NGINX_HOST=foobar.com

- NGINX_PORT=80

创建configmap

[root@k8s-master configmap]# kubectl create configmap nginx-config --from-literal=NGINX_PORT=888 --from-literal=SERVER_NAME=www.wx.com
configmap/nginx-config created
[root@k8s-master configmap]# kubectl describe configmap nginx-config
Name:         nginx-config
Namespace:    default
Labels:       <none>
Annotations:  <none>

Data
====
NGINX_PORT:
----
888
SERVER_NAME:
----
www.wx.com
Events:  <none>
[root@k8s-master configmap]#
[root@k8s-master configmap]#
[root@k8s-master configmap]# kubectl get cm nginx-config -o yaml
apiVersion: v1
data:
  NGINX_PORT: "888"
  SERVER_NAME: www.wx.com
kind: ConfigMap
metadata:
  creationTimestamp: "2019-09-04T07:43:15Z"
  name: nginx-config
  namespace: default
  resourceVersion: "812366"
  selfLink: /api/v1/namespaces/default/configmaps/nginx-config
  uid: b8c71e6f-8a37-45b3-ac87-eb9547b78d8d
[root@k8s-master configmap]#

创建Nginx-deployment

# cat nginx_dep.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80
        envFrom:
        - configMapRef:
            name: nginx-config
       # env: #两种方法都行
       # - name: NGINX_SERVER_PORT   #pod容器中的环境变量名字
       #   valueFrom:
       #     configMapKeyRef:
       #       name: nginx-config       #configmap的名字
       #       key: nginx_port           #configmap中定义的key
       #
       # - name: NGINX_SERVER_NAME
       #   valueFrom:
       #     configMapKeyRef:
       #       name: nginx-config
       #       key: server_name

验证

[root@k8s-master configmap]# kubectl exec  -it nginx-deployment-b7cbfc4c-6w6p6 env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=nginx-deployment-b7cbfc4c-6w6p6
TERM=xterm
NGINX_SERVER_PORT=888
NGINX_SERVER_NAME=www.wx.com
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_PORT=tcp://10.96.0.1:443
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_PORT_443_TCP_PORT=443
KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
KUBERNETES_SERVICE_HOST=10.96.0.1
KUBERNETES_SERVICE_PORT=443
NGINX_VERSION=1.17.3
NJS_VERSION=0.3.5
PKG_RELEASE=1~buster
HOME=/root

Dashboard查看

3.2 NGINX通过volumeMount使用ConfigMap

https://blog.51cto.com/passed/2348256

文件创建configmap

# cat config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config2
data:
  nginx.conf: |+                      ##这一段就是内容,nginx.conf是该文件的键
    server {
       listen       8081;
       server_name  www.sb.com 127.0.0.1;
       root         /html;

       location / {
       }

    }

[root@k8s-master configmap]# kubectl apply -f config.yaml
configmap/nginx-config2 unchanged
[root@k8s-master configmap]# kubectl get cm nginx-config2
NAME            DATA   AGE
nginx-config2   1      18m

[root@k8s-master configmap]# kubectl describe cm nginx-config2
Name:         nginx-config2
Namespace:    default
Labels:       <none>
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"v1","data":{"nginx.conf":"server {\n   listen       8081;\n   server_name  www.sb.com 127.0.0.1;\n   root         /html;\n\...

Data
====
nginx.conf:
----
server {
   listen       8081;
   server_name  www.sb.com 127.0.0.1;
   root         /html;

   location / {
   }

}

Events:  <none>

创建Nginx-dep和svc

# cat nginx_dep.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80
        volumeMounts:                        #挂载
        - name: nginxconfig                  #调用下面定义的存储卷, 名字要一致
          mountPath: /etc/nginx/conf.d/    #pod容器目录
          readOnly: true                  #只读
      volumes:                   #创建一个存储卷
      - name: nginxconfig        #定义存储卷名字
        configMap:                 #定义存储卷类型为configMap
          name: nginx-config2         #引用名字叫nginx-file的configmap,

---
apiVersion: v1
kind: Service
metadata:
  name: nginx-svc
spec:
  type: NodePort
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 8081
      targetPort: 8081
      nodePort: 30081

验证

[root@k8s-master configmap]# kubectl exec  -it nginx-deployment-6c7bc64dbf-dd9s7 /bin/bash
root@nginx-deployment-6c7bc64dbf-dd9s7:/# cd /etc/nginx/
root@nginx-deployment-6c7bc64dbf-dd9s7:/etc/nginx# cd conf.d/
root@nginx-deployment-6c7bc64dbf-dd9s7:/etc/nginx/conf.d# ls -al
total 4
drwxrwxrwx 3 root root   74 Sep  4 08:05 .
drwxr-xr-x 3 root root 4096 Aug 15 21:22 ..
drwxr-xr-x 2 root root   23 Sep  4 08:05 ..2019_09_04_08_05_02.735756292
lrwxrwxrwx 1 root root   31 Sep  4 08:05 ..data -> ..2019_09_04_08_05_02.735756292
lrwxrwxrwx 1 root root   17 Sep  4 08:05 nginx.conf -> ..data/nginx.conf
#可以看到这个配置文件是一个相对路径不是实体文件
root@nginx-deployment-6c7bc64dbf-dd9s7:/etc/nginx/conf.d#
root@nginx-deployment-6c7bc64dbf-dd9s7:/# mkdir /html
root@nginx-deployment-6c7bc64dbf-dd9s7:/# cd /html/
root@nginx-deployment-6c7bc64dbf-dd9s7:/html# ls
root@nginx-deployment-6c7bc64dbf-dd9s7:/html# echo 'cc' >> index.html
root@nginx-deployment-6c7bc64dbf-dd9s7:/html# exit
[root@k8s-master configmap]#
[root@k8s-master configmap]#
[root@k8s-master configmap]# curl 10.254.2.74:8081
cc
[root@k8s-master configmap]#
[root@k8s-master configmap]# curl  10.6.76.24:30091
cc
[root@k8s-master configmap]#

3.3 ConfigMap的热更新

使用该 ConfigMap 挂载的 Env 不会同步更新；
使用该 ConfigMap 挂载的 Volume 中的数据需要一段时间（实测大概10秒）才能同步更新。

# cat config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config2
data:
  nginx.conf: |+                      ##这一段就是内容,nginx.conf是该文件的键
    server {
       listen       8081;
       server_name  www.new-sb.com 127.0.0.1;
       root         /html;

       location / {
       }

    }

# cat config.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-config2
data:
  nginx.conf: |+                      ##这一段就是内容,nginx.conf是该文件的键
    server {
       listen       8081;
       server_name  www.new-sb.com 127.0.0.1;
       root         /html;

       location / {
       }

    }

3.4 通过configmap更新Mysql配置文件

https://www.cnblogs.com/chy-op/p/9811852.html

https://www.cnblogs.com/wzlinux/p/10159340.html#%E6%9C%80%E4%BD%B3%E4%BD%BF%E7%94%A8%E6%96%B9%E6%B3%95

大多数情况下，配置信息都以文件形式提供，所以在创建 ConfigMap 时通常采用 --from-file 或 YAML 方式，读取 ConfigMap 时通常采用 Volume 方式。
比如我们的 MySQL 配置文件/etc/my.cnf。

创建configmap

# cat my.conf.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: mysql-config
data:
  my.cnf: |+
   [mysqld]
   datadir=/var/lib/mysql
   socket=/var/lib/mysql/mysql.sock
   symbolic-links=0
   [mysqld_safe]
   log-error=/var/log/mysql/mysql.log
   pid-file=/var/run/mysql/mysql.pid

[root@k8s-master configmap]# kubectl apply  -f my.conf.yaml
configmap/mysql-config unchanged

查看创建的cm

[root@k8s-master configmap]# kubectl get cm mysql-config
NAME           DATA   AGE
mysql-config   1      50s
[root@k8s-master configmap]# kubectl describe cm mysql-config
Name:         mysql-config
Namespace:    default
Labels:       <none>
Annotations:  kubectl.kubernetes.io/last-applied-configuration:
                {"apiVersion":"v1","data":{"my.cnf":"[mysqld]\ndatadir=/var/lib/mysql\nsocket=/var/lib/mysql/mysql.sock\nsymbolic-links=0\n[mysqld_safe]\n...

Data
====
my.cnf:
----
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
symbolic-links=0
[mysqld_safe]
log-error=/var/log/mysql/mysql.log
pid-file=/var/run/mysql/mysql.pid

Events:  <none>
[root@k8s-master configmap]#

在Pod 中使用此 ConfigMap

Version: apps/v1
kind: Deployment
metadata:
  name: mysql-dev
  namespace: default
  labels:
    app: mysql-dev
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql-dev
  template:
    metadata:
      labels:
        app: mysql-dev
    spec:
      containers:
      - name: mysql
        image: mysql:5.7
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456"
        ports:
        - containerPort: 3306
        volumeMounts:
        - name: mysqlconfig-volume                      #<--（1）
          mountPath: "/etc/mysql/mysql.conf.d/"    #<--（2）
      volumes:
      - name: mysqlconfig-volume                       # <--（3）
        configMap:                                # <--（4）
          name: mysql-config                      # <--（5）

　其中，（1）表示一个挂载点的名称

　　　　　（2）表示新挂载点的路径，这里就是mysql配置文件的路径

　　　　（3）表示挂载点的名称

　　　　（4）使用configmap

　　　　（5）使用名为mysql-config，configmap的name

创建 Pod 并读取配置信息

[root@k8s-master configmap]# kubectl apply -f mysql.yaml
deployment.apps/mysql-dev unchanged
[root@k8s-master configmap]# kubectl get pod
NAME                         READY   STATUS    RESTARTS   AGE
mysql-dev-767875cf5f-pqd6x   1/1     Running   0          4m46s
[root@k8s-master configmap]# kubectl exec -it mysql-dev-767875cf5f-pqd6x /bin/bash
root@mysql-dev-767875cf5f-pqd6x:/# cd /etc/mysql/
root@mysql-dev-767875cf5f-pqd6x:/etc/mysql# ls -al
total 12
drwxr-xr-x  4 root root   94 Aug 14 06:09 .
drwxr-xr-x 33 root root 4096 Sep  4 09:11 ..
drwxr-xr-x  2 root root   62 Aug 14 06:09 conf.d
lrwxrwxrwx  1 root root   24 Aug 14 06:09 my.cnf -> /etc/alternatives/my.cnf
-rw-r--r--  1 root root  839 Jul  9  2016 my.cnf.fallback
-rw-r--r--  1 root root  796 Jun 10 14:58 mysql.cnf
drwxrwxrwx  3 root root   70 Sep  4 09:11 mysql.conf.d
root@mysql-dev-767875cf5f-pqd6x:/etc/mysql# cd mysql.conf.d/
root@mysql-dev-767875cf5f-pqd6x:/etc/mysql/mysql.conf.d# ls -al
total 0
drwxrwxrwx 3 root root 70 Sep  4 09:11 .
drwxr-xr-x 4 root root 94 Aug 14 06:09 ..
drwxr-xr-x 2 root root 19 Sep  4 09:11 ..2019_09_04_09_11_55.727621531
lrwxrwxrwx 1 root root 31 Sep  4 09:11 ..data -> ..2019_09_04_09_11_55.727621531
lrwxrwxrwx 1 root root 13 Sep  4 09:11 my.cnf -> ..data/my.cnf
root@mysql-dev-767875cf5f-pqd6x:/etc/mysql/mysql.conf.d# cat my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
symbolic-links=0
[mysqld_safe]
log-error=/var/log/mysql/mysql.log
pid-file=/var/run/mysql/mysql.pid
root@mysql-dev-767875cf5f-pqd6x:/etc/mysql/mysql.conf.d#

posted on 2019-10-14 14:12 光阴8023 阅读(2336) 评论(0) 编辑收藏举报