Kubernetes外挂配置管理
其他容器编排调度工具会大谈特谈“轻应用”、“十二要素应用”，这样就势必会对企业级复杂应用做很大的改动。Kubernetes是为了解决“如何合理使用容器支撑企业级复杂应用”这个问题而诞生的，所以它的设计理念是要支持绝大多数应用的原生形态。例如，很多应用程序的配置需要通过配置文件，命令行参数和环境变量的组合配置来完成（“十二要素应用”等均要求去配置）。这些配置应该从image内容中解耦，以此来保持容器化应用程序的可移植性。ConfigMap API资源提供了将配置数据注入容器的方式，同时保证该机制对容器来说是透明的。ConfigMap可以被用来保存单个属性，也可以用来保存整个配置文件或者JSON二进制大对象。ConfigMap API资源存储键/值对配置数据，这些数据可以在pods里使用。ConfigMap跟Secrets类似，但是ConfigMap可以更方便的处理不包含敏感信息的字符串。示例如下：
kind: ConfigMap
apiVersion: v1
metadata:
creationTimestamp:
2016-02-18T19:14:38Z name: example
-config namespace: default
data:
example.property.
1: hello example.property.
2: world example.property.
file: |- property.
1=value-1 property.
2=value-2 property.
3=value-3
通过示例代码可以看到：ConfigMap可以包含细粒度的配置项，如：example.property.1；也可以包含粗粒度的配置文件，如：example.property.file。
1、创建ConfigMap
1.1 从文件夹创建
# cat /home/yaml/propertirs/game.properties
enemies
=aliens
lives
=3
enemies.cheat
=true
enemies.cheat.level
=noGoodRotten
secret.code.passphrase
=UUDDLRLRBABAS
secret.code.allowed
=true
secret.code.lives
=30
[iyunv@k8s
-master propertirs]# cat /home/yaml/propertirs/ui.properties
color.good
=purple
color.bad
=yellow
allow.textmode
=true
how.
nice.to.look=fairlyNice
[iyunv@k8s
-master propertirs]# kubectl create configmap game-config --from-file=/home/yaml/propertirs/
configmap
"game-config" created
[iyunv@k8s
-master propertirs]# kubectl describe configmaps game-config
#该方法只能得到ConfigMap的Key和size
Name: game
-config
Namespace: default
Labels:
<none>
Annotations:
<none>
Data
====
ui.properties:
83 bytes
game.properties:
158 bytes
#若想得到详细信息，可通过以下命令：
[iyunv@k8s
-master propertirs]# kubectl get configmaps game-config -o yaml
apiVersion: v1
data:
game.properties:
| enemies
=aliens lives
=3 enemies.cheat
=true enemies.cheat.level
=noGoodRotten secret.code.passphrase
=UUDDLRLRBABAS secret.code.allowed
=true secret.code.lives
=30 ui.properties:
| color.good
=purple color.bad
=yellow allow.textmode
=true how.
nice.to.look=fairlyNice
kind: ConfigMap
metadata:
creationTimestamp:
2017-03-21T03:22:34Z name: game
-config namespace: default
resourceVersion:
"3002770" selfLink:
/api/v1/namespaces/default/configmaps/game-config uid: a04f90f0
-0de5-11e7-b3d5-fa163ebba51b
1.2 从文件创建
# kubectl create configmap game-config-2 --from-file=/home/yaml/propertirs/game.properties --from-file=/home/yaml/propertirs/ui.properties
configmap
"game-config-2" created
[iyunv@k8s
-master propertirs]# kubectl get configmaps game-config-2 -o yaml
apiVersion: v1
data:
game.properties:
| enemies
=aliens lives
=3 enemies.cheat
=true enemies.cheat.level
=noGoodRotten secret.code.passphrase
=UUDDLRLRBABAS secret.code.allowed
=true secret.code.lives
=30 ui.properties:
| color.good
=purple color.bad
=yellow allow.textmode
=true how.
nice.to.look=fairlyNice
kind: ConfigMap
metadata:
creationTimestamp:
2017-03-21T03:30:15Z name: game
-config-2 namespace: default
resourceVersion:
"3003415" selfLink:
/api/v1/namespaces/default/configmaps/game-config-2 uid: b2e4dfab
-0de6-11e7-b3d5-fa163ebba51b
1.3指定data中的key
# kubectl create configmap game-config-3 --from-file=game-special-key=/home/yaml/propertirs/game.properties
configmap
"game-config-3" created
[iyunv@k8s
-master propertirs]# kubectl get configmaps game-config-3 -o yaml
apiVersion: v1
data:
game
-special-key: | enemies
=aliens lives
=3 enemies.cheat
=true enemies.cheat.level
=noGoodRotten secret.code.passphrase
=UUDDLRLRBABAS secret.code.allowed
=true secret.code.lives
=30
kind: ConfigMap
metadata:
creationTimestamp:
2017-03-21T03:33:23Z name: game
-config-3 namespace: default
resourceVersion:
"3003678" selfLink:
/api/v1/namespaces/default/configmaps/game-config-3 uid: 2345dad3
-0de7-11e7-b3d5-fa163ebba51b
1.4指定具体的值
# kubectl create configmap game-config-4 --from-literal=special.user=zhenyu --from-literal=special.passwd=yaodidiao
configmap
"game-config-4" created
[iyunv@k8s
-master propertirs]# kubectl get configmaps game-config-4 -o yaml
apiVersion: v1
data:
special.
passwd: yaodidiao special.user: zhenyu
kind: ConfigMap
metadata:
creationTimestamp:
2017-03-21T03:36:12Z name: game
-config-4 namespace: default
resourceVersion:
"3003915" selfLink:
/api/v1/namespaces/default/configmaps/game-config-4 uid: 8802f6d2
-0de7-11e7-b3d5-fa163ebba51b
2、使用ConfigMap
2.1 环境变量或参数
创建一个Pod，并将一个已经创建好的ConfigMap作为环境变量，注入到Pod中。
# kubectl get configmaps game-config-4 -o yaml
apiVersion: v1
data:
special.
passwd: yaodidiao special.user: zhenyu
kind: ConfigMap
metadata:
creationTimestamp:
2017-03-21T03:36:12Z name: game
-config-4 namespace: default
resourceVersion:
"3003915" selfLink:
/api/v1/namespaces/default/configmaps/game-config-4 uid: 8802f6d2
-0de7-11e7-b3d5-fa163ebba51b
[iyunv@k8s
-master propertirs]# cat testEnv.yaml
apiVersion: v1
kind: Pod
metadata:
labels:
name: testenv
role: master
name: testenv
spec:
containers:
- name: testenv image: busybox
imagePullPolicy: IfNotPresent
env:- name: SPECIAL_USER valueFrom:
configMapKeyRef:
name: game
-config-4 key: special.user
command:
- sleep - "360000"
# kubectl create -f testEnv.yaml
pod "testenv" created
# kubectl exec -ti testenv sh
/ # echo $SPECIAL_USER
zhenyu
/ #
2.2 挂载文件数据卷
# kubectl get configmaps game-config -o yaml
apiVersion: v1
data:
game.properties:
| enemies
=aliens lives
=3 enemies.cheat
=true enemies.cheat.level
=noGoodRotten secret.code.passphrase
=UUDDLRLRBABAS secret.code.allowed
=true secret.code.lives
=30 ui.properties:
| color.good
=purple color.bad
=yellow allow.textmode
=true how.
nice.to.look=fairlyNice
kind: ConfigMap
metadata:
creationTimestamp:
2017-03-21T03:22:34Z name: game
-config namespace: default
resourceVersion:
"3002770" selfLink:
/api/v1/namespaces/default/configmaps/game-config uid: a04f90f0
-0de5-11e7-b3d5-fa163ebba51b
[iyunv@k8s
-master propertirs]# cat testVolume.yaml
apiVersion: v1
kind: Pod
metadata:
labels:
name: testvolume
role: master
name: testvolume
spec:
containers:
- name: testvolume image: busybox
imagePullPolicy: IfNotPresent
volumeMounts:
- name: config-volume mountPath:
/etc/config command:
- sleep - "360000"
volumes:
- name: config-volume
configMap:
name: game-config
# kubectl create -f testVolume.yaml
pod "testvolume" created
# kubectl exec -ti testvolume sh
/ # cd /etc/config/
/etc/config # ls
game.propertiesui.properties
/etc/config # cat game.properties
enemies=aliens
lives=3
enemies.cheat=true
enemies.cheat.level=noGoodRotten
secret.code.passphrase=UUDDLRLRBABAS
secret.code.allowed=true
secret.code.lives=30
/etc/config # cat ui.properties
color.good=purple
color.bad=yellow
allow.textmode=true
how.nice.to.look=fairlyNice
/etc/config #
2.3 挂载信息数据卷
# cat testVolume.yaml
apiVersion: v1
kind: Pod
metadata:
labels:
name: testvolume
role: master
name: testvolume
spec:
containers:
- name: testvolume image: busybox
imagePullPolicy: IfNotPresent
volumeMounts:
- name: config-volume mountPath:
/etc/config command:
- sleep - "360000"
volumes:
- name: config-volume
configMap:
name: game-config-4
# kubectl getconfigmaps game-config-4 -o yaml
apiVersion: v1
data:
special.passwd: yaodidiao
special.user: zhenyuyaodidiao
kind: ConfigMap
metadata:
creationTimestamp: 2017-03-21T06:29:29Z
name: game-config-4
namespace: default
resourceVersion: "3018779"
selfLink: /api/v1/namespaces/default/configmaps/game-config-4
uid: bd086dca-0dff-11e7-b3d5-fa163ebba51b
# kubectl create -f testVolume.yaml
pod "testvolume" created
# kubectl exec -ti testvolume sh
/ # cd /etc/config/
/etc/config # ls
special.passwdspecial.user
/etc/config # cat special.user
zhenyuyaodidiao/etc/config #
/etc/config # exit
2.4 热更新
当ConfigMap以数据卷的形式挂载进Pod的时，这时更新ConfigMap（或删掉重建ConfigMap），Pod内挂载的配置信息会热更新。这时可以增加一些监测配置文件变更的脚本，然后reload对应服务。
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