396 lines
9.9 KiB
Markdown
396 lines
9.9 KiB
Markdown
<h1><center>Kubernetes资源对象ConfigMap</center></h1>
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著作：行癫 <盗版必究>
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------
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## 一：ConfigMap
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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；ConfigMap与 Secret 类似
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#### 1.ConfigMap与 Secret 的区别
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ConfigMap 保存的是不需要加密的、应用所需的配置信息
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ConfigMap 的用法几乎与 Secret 完全相同：可以使用 kubectl create configmap 从文件或者目录创建 ConfigMap，也可以直接编写 ConfigMap 对象的 YAML 文件
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#### 2.创建ConfigMap
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方式1：通过直接在命令行中指定configmap参数创建，即--from-literal
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方式2：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>
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方式3：通过指定目录创建，即将一个目录下的所有配置文件创建为一个ConfigMap，--from-file=<目录>
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方式4：事先写好标准的configmap的yaml文件，然后kubectl create -f 创建
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通过命令行参数--from-literal创建：
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创建命令
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```shell
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[root@master yaml]# kubectl create configmap test-config1 --from-literal=db.host=10.5.10.116 --from-literal=db.port='3306'
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configmap/test-config1 created
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```
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结果如下面的data内容所示
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```shell
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[root@master yaml]# kubectl get configmap test-config1 -o yaml
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apiVersion: v1
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data:
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db.host: 10.5.10.116
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db.port: "3306"
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kind: ConfigMap
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metadata:
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creationTimestamp: "2019-02-14T08:22:34Z"
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name: test-config1
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namespace: default
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resourceVersion: "7587"
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selfLink: /api/v1/namespaces/default/configmaps/test-config1
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uid: adfff64c-3031-11e9-abbe-000c290a5b8b
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```
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通过指定文件创建：
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编辑配置文件app.properties内容如下
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```shell
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[root@master yaml]# cat app.properties
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property.1 = value-1
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property.2 = value-2
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property.3 = value-3
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property.4 = value-4
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[mysqld]
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!include /home/wing/mysql/etc/mysqld.cnf
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port = 3306
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socket = /home/wing/mysql/tmp/mysql.sock
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pid-file = /wing/mysql/mysql/var/mysql.pid
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basedir = /home/mysql/mysql
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datadir = /wing/mysql/mysql/var
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```
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创建（可以有多个--from-file）
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```shell
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[root@master yaml]# kubectl create configmap test-config2 --from-file=./app.properties
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```
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结果如下面data内容所示
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```shell
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[root@master yaml]# kubectl get configmap test-config2 -o yaml
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apiVersion: v1
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data:
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app.properties: |
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property.1 = value-1
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property.2 = value-2
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property.3 = value-3
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property.4 = value-4
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[mysqld]
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!include /home/wing/mysql/etc/mysqld.cnf
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port = 3306
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socket = /home/wing/mysql/tmp/mysql.sock
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pid-file = /wing/mysql/mysql/var/mysql.pid
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basedir = /home/mysql/mysql
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datadir = /wing/mysql/mysql/var
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kind: ConfigMap
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metadata:
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creationTimestamp: "2019-02-14T08:29:33Z"
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name: test-config2
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namespace: default
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resourceVersion: "8176"
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selfLink: /api/v1/namespaces/default/configmaps/test-config2
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uid: a8237769-3032-11e9-abbe-000c290a5b8b
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```
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通过指定文件创建时，configmap会创建一个key/value对，key是文件名，value是文件内容。如不想configmap中的key为默认的文件名，可以在创建时指定key名字
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```shell
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[root@master yaml]# kubectl create configmap game-config-3 --from-file=<my-key-name>=<path-to-file>
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```
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指定目录创建：
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configs 目录下的config-1和config-2内容如下所示
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```shell
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[root@master yaml]# tail configs/config-1
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aaa
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bbb
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c=d
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[root@master yaml]# tail configs/config-2
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eee
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fff
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h=k
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```
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创建
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```shell
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[root@master yaml]# kubectl create configmap test-config3 --from-file=./configs
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```
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结果下面data内容所示
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```shell
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[root@master yaml]# kubectl get configmap test-config3 -o yaml
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apiVersion: v1
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data:
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config-1: |
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aaa
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bbb
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c=d
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config-2: |
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eee
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fff
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h=k
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kind: ConfigMap
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metadata:
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creationTimestamp: "2019-02-14T08:37:05Z"
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name: test-config3
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namespace: default
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resourceVersion: "8808"
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selfLink: /api/v1/namespaces/default/configmaps/test-config3
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uid: b55ffbeb-3033-11e9-abbe-000c290a5b8b
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```
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指定目录创建时，configmap内容中的各个文件会创建一个key/value对，key是文件名，value是文件内容，忽略子目录
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通过事先写好configmap的标准yaml文件创建：
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yaml文件内容如下： 注意其中一个key的value有多行内容时的写法
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```shell
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[root@master yaml]# cat configmap.yaml
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: test-config4
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namespace: default
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data:
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cache_host: memcached-gcxt
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cache_port: "11211"
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cache_prefix: gcxt
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my.cnf: |
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[mysqld]
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log-bin = mysql-bin
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haha = hehe
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```
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创建
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```shell
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[root@master yaml]# kubectl apply -f configmap.yaml
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configmap/test-config4 created
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```
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结果如下面data内容所示
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```shell
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[root@master yaml]# kubectl get configmap test-config4 -o yaml
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apiVersion: v1
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data:
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cache_host: memcached-gcxt
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cache_port: "11211"
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cache_prefix: gcxt
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my.cnf: |
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[mysqld]
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log-bin = mysql-bin
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haha = hehe
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kind: ConfigMap
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metadata:
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annotations:
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kubectl.kubernetes.io/last-applied-configuration: |
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{"apiVersion":"v1","data":{"cache_host":"memcached-gcxt","cache_port":"11211","cache_prefix":"gcxt","my.cnf":"[mysqld]\nlog-bin = mysql-bin\nhaha = hehe\n"},"kind":"ConfigMap","metadata":{"annotations":{},"name":"test-config4","namespace":"default"}}
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creationTimestamp: "2019-02-14T08:46:57Z"
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name: test-config4
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namespace: default
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resourceVersion: "9639"
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selfLink: /api/v1/namespaces/default/configmaps/test-config4
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uid: 163fbe1e-3035-11e9-abbe-000c290a5b8b
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```
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查看configmap的详细信息
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```shell
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[root@master yaml]# kubectl describe configmap
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```
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#### 3.使用ConfigMap
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通过环境变量的方式，直接传递pod
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通过在pod的命令行下运行的方式
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使用volume的方式挂载入到pod内
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示例ConfigMap文件：
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```shell
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: special-config
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namespace: default
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data:
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special.how: very
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special.type: charm
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```
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通过环境变量使用：
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使用valueFrom、configMapKeyRef、name、key指定要用的key
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```shell
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[root@master yaml]# cat testpod.yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: dapi-test-pod
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spec:
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containers:
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- name: test-container
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image: daocloud.io/library/nginx
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env:
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- name: SPECIAL_LEVEL_KEY //这里是容器里设置的新变量的名字
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valueFrom:
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configMapKeyRef:
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name: special-config //这里是来源于哪个configMap
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key: special.how //configMap里的key
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- name: SPECIAL_TYPE_KEY
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valueFrom:
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configMapKeyRef:
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name: special-config
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key: special.type
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restartPolicy: Never
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```
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测试
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```shell
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[root@master yaml]# kubectl exec -it dapi-test-pod /bin/bash
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root@dapi-test-pod:/# echo $SPECIAL_TYPE_KEY
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charm
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```
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通过envFrom、configMapRef、name使得configmap中的所有key/value对都自动变成环境变量
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```shell
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apiVersion: v1
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kind: Pod
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metadata:
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name: dapi-test-pod
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spec:
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containers:
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- name: test-container
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image: daocloud.io/library/nginx
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envFrom:
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- configMapRef:
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name: special-config
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restartPolicy: Never
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```
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这样容器里的变量名称直接使用configMap里的key名
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```shell
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[root@master yaml]# kubectl exec -it dapi-test-pod /bin/bash
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root@dapi-test-pod:/# env
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HOSTNAME=dapi-test-pod
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NJS_VERSION=1.15.8.0.2.7-1~stretch
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NGINX_VERSION=1.15.8-1~stretch
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KUBERNETES_PORT_443_TCP_PROTO=tcp
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KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
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KUBERNETES_PORT=tcp://10.96.0.1:443
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PWD=/
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special.how=very
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HOME=/root
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KUBERNETES_SERVICE_PORT_HTTPS=443
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KUBERNETES_PORT_443_TCP_PORT=443
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KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
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TERM=xterm
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SHLVL=1
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KUBERNETES_SERVICE_PORT=443
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PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
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special.type=charm
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KUBERNETES_SERVICE_HOST=10.96.0.1
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```
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作为volume挂载使用：
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```shell
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: nginx-configmap
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spec:
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replicas: 1
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selector:
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matchLabels:
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app: nginx
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template:
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metadata:
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labels:
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app: nginx
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spec:
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containers:
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- name: nginx-configmap
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image: daocloud.io/library/nginx:latest
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ports:
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- containerPort: 80
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volumeMounts:
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- name: config-volume3
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mountPath: /tmp/config3
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volumes:
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- name: config-volume3
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configMap:
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name: test-config-3
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```
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进入容器中/tmp/config4查看
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```shell
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[root@master yaml]# kubectl exec -it nginx-configmap-7447bf77d6-svj2t /bin/bash
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root@nginx-configmap-7447bf77d6-svj2t:/# ls /tmp/config4/
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cache_host cache_port cache_prefix my.cnf
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root@nginx-configmap-7447bf77d6-svj2t:/# cat /tmp/config4/cache_host
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memcached-gcxt
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可以看到，在config4文件夹下以每一个key为文件名value为值创建了多个文件。
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```
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假如不想以key名作为配置文件名可以引入items 字段，在其中逐个指定要用相对路径path替换的key：
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```shell
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volumes:
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- name: config-volume4
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configMap:
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name: test-config4
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items:
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- key: my.cnf //原来的key名
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path: mysql-key
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- key: cache_host //原来的key名
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path: cache-host
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```
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注意：
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删除configmap后原pod不受影响；然后再删除pod后，重启的pod的events会报找不到cofigmap的volume
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pod起来后再通过kubectl edit configmap …修改configmap，过一会pod内部的配置也会刷新
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在容器内部修改挂进去的配置文件后，过一会内容会再次被刷新为原始configmap内容
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