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kubernetes/kubernetes-MD/kubernetes资源对象ConfigMap.md

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<h1><center>Kubernetes资源对象ConfigMap</center></h1>
著作：行癫 <盗版必究>
------
## 一：ConfigMap
​ 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
#### 1.ConfigMap与 Secret 的区别
​ ConfigMap 保存的是不需要加密的、应用所需的配置信息
​ 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
#### 2.创建ConfigMap
​ 方式1：通过直接在命令行中指定configmap参数创建，即--from-literal
​ 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>
​ 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>
​ 方式4：事先写好标准的configmap的yaml文件，然后kubectl create -f 创建
通过命令行参数--from-literal创建：
​ 创建命令
```shell
[root@master yaml]# kubectl create configmap test-config1 --from-literal=db.host=10.5.10.116 --from-literal=db.port='3306'
configmap/test-config1 created
```
​ 结果如下面的data内容所示
```shell
[root@master yaml]# kubectl get configmap test-config1 -o yaml
apiVersion: v1
data:
db.host: 10.5.10.116
db.port: "3306"
kind: ConfigMap
metadata:
creationTimestamp: "2019-02-14T08:22:34Z"
name: test-config1
namespace: default
resourceVersion: "7587"
selfLink: /api/v1/namespaces/default/configmaps/test-config1
uid: adfff64c-3031-11e9-abbe-000c290a5b8b
```
通过指定文件创建：
​ 编辑配置文件app.properties内容如下
```shell
[root@master yaml]# cat app.properties
property.1 = value-1
property.2 = value-2
property.3 = value-3
property.4 = value-4
[mysqld]
!include /home/wing/mysql/etc/mysqld.cnf
port = 3306
socket = /home/wing/mysql/tmp/mysql.sock
pid-file = /wing/mysql/mysql/var/mysql.pid
basedir = /home/mysql/mysql
datadir = /wing/mysql/mysql/var
```
​ 创建（可以有多个--from-file）
```shell
[root@master yaml]# kubectl create configmap test-config2 --from-file=./app.properties
```
​ 结果如下面data内容所示
```shell
[root@master yaml]# kubectl get configmap test-config2 -o yaml
apiVersion: v1
data:
app.properties: |
property.1 = value-1
property.2 = value-2
property.3 = value-3
property.4 = value-4
[mysqld]
!include /home/wing/mysql/etc/mysqld.cnf
port = 3306
socket = /home/wing/mysql/tmp/mysql.sock
pid-file = /wing/mysql/mysql/var/mysql.pid
basedir = /home/mysql/mysql
datadir = /wing/mysql/mysql/var
kind: ConfigMap
metadata:
creationTimestamp: "2019-02-14T08:29:33Z"
name: test-config2
namespace: default
resourceVersion: "8176"
selfLink: /api/v1/namespaces/default/configmaps/test-config2
uid: a8237769-3032-11e9-abbe-000c290a5b8b
```
​ 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
```shell
[root@master yaml]# kubectl create configmap game-config-3 --from-file=<my-key-name>=<path-to-file>
```
指定目录创建：
​ configs 目录下的config-1和config-2内容如下所示
```shell
[root@master yaml]# tail configs/config-1
aaa
bbb
c=d
[root@master yaml]# tail configs/config-2
eee
fff
h=k
```
​ 创建
```shell
[root@master yaml]# kubectl create configmap test-config3 --from-file=./configs
```
​ 结果下面data内容所示
```shell
[root@master yaml]# kubectl get configmap test-config3 -o yaml
apiVersion: v1
data:
config-1: |
aaa
bbb
c=d
config-2: |
eee
fff
h=k
kind: ConfigMap
metadata:
creationTimestamp: "2019-02-14T08:37:05Z"
name: test-config3
namespace: default
resourceVersion: "8808"
selfLink: /api/v1/namespaces/default/configmaps/test-config3
uid: b55ffbeb-3033-11e9-abbe-000c290a5b8b
```
​ 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
通过事先写好configmap的标准yaml文件创建：
​ 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
```shell
[root@master yaml]# cat configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: test-config4
namespace: default
data:
cache_host: memcached-gcxt
cache_port: "11211"
cache_prefix: gcxt
my.cnf: |
[mysqld]
log-bin = mysql-bin
haha = hehe
```
​ 创建
```shell
[root@master yaml]# kubectl apply -f configmap.yaml
configmap/test-config4 created
```
​ 结果如下面data内容所示
```shell
[root@master yaml]# kubectl get configmap test-config4 -o yaml
apiVersion: v1
data:
cache_host: memcached-gcxt
cache_port: "11211"
cache_prefix: gcxt
my.cnf: |
[mysqld]
log-bin = mysql-bin
haha = hehe
kind: ConfigMap
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"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"}}
creationTimestamp: "2019-02-14T08:46:57Z"
name: test-config4
namespace: default
resourceVersion: "9639"
selfLink: /api/v1/namespaces/default/configmaps/test-config4
uid: 163fbe1e-3035-11e9-abbe-000c290a5b8b
```
​ 查看configmap的详细信息
```shell
[root@master yaml]# kubectl describe configmap
```
#### 3.使用ConfigMap
​ 通过环境变量的方式，直接传递pod
​ 通过在pod的命令行下运行的方式
​ 使用volume的方式挂载入到pod内
示例ConfigMap文件：
```shell
apiVersion: v1
kind: ConfigMap
metadata:
name: special-config
namespace: default
data:
special.how: very
special.type: charm
```
通过环境变量使用：
​ 使用valueFrom、configMapKeyRef、name、key指定要用的key
```shell
[root@master yaml]# cat testpod.yaml
apiVersion: v1
kind: Pod
metadata:
name: dapi-test-pod
spec:
containers:
- name: test-container
image: daocloud.io/library/nginx
env:
- name: SPECIAL_LEVEL_KEY //这里是容器里设置的新变量的名字
valueFrom:
configMapKeyRef:
name: special-config //这里是来源于哪个configMap
key: special.how //configMap里的key
- name: SPECIAL_TYPE_KEY
valueFrom:
configMapKeyRef:
name: special-config
key: special.type
restartPolicy: Never
```
​ 测试
```shell
[root@master yaml]# kubectl exec -it dapi-test-pod /bin/bash
root@dapi-test-pod:/# echo $SPECIAL_TYPE_KEY
charm
```
​ 通过envFrom、configMapRef、name使得configmap中的所有key/value对都自动变成环境变量
```shell
apiVersion: v1
kind: Pod
metadata:
name: dapi-test-pod
spec:
containers:
- name: test-container
image: daocloud.io/library/nginx
envFrom:
- configMapRef:
name: special-config
restartPolicy: Never
```
​ 这样容器里的变量名称直接使用configMap里的key名
```shell
[root@master yaml]# kubectl exec -it dapi-test-pod /bin/bash
root@dapi-test-pod:/# env
HOSTNAME=dapi-test-pod
NJS_VERSION=1.15.8.0.2.7-1~stretch
NGINX_VERSION=1.15.8-1~stretch
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
KUBERNETES_PORT=tcp://10.96.0.1:443
PWD=/
special.how=very
HOME=/root
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_PORT_443_TCP_PORT=443
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
TERM=xterm
SHLVL=1
KUBERNETES_SERVICE_PORT=443
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
special.type=charm
KUBERNETES_SERVICE_HOST=10.96.0.1
```
作为volume挂载使用：
```shell
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-configmap
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx-configmap
image: daocloud.io/library/nginx:latest
ports:
- containerPort: 80
volumeMounts:
- name: config-volume3
mountPath: /tmp/config3
volumes:
- name: config-volume3
configMap:
name: test-config-3
```
​ 进入容器中/tmp/config4查看
```shell
[root@master yaml]# kubectl exec -it nginx-configmap-7447bf77d6-svj2t /bin/bash
root@nginx-configmap-7447bf77d6-svj2t:/# ls /tmp/config4/
cache_host cache_port cache_prefix my.cnf
root@nginx-configmap-7447bf77d6-svj2t:/# cat /tmp/config4/cache_host
memcached-gcxt
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。
```
​ 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：
```shell
volumes:
- name: config-volume4
configMap:
name: test-config4
items:
- key: my.cnf //原来的key名
path: mysql-key
- key: cache_host //原来的key名
path: cache-host
```
注意：
​ 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
​ 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
​ 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