目录贴：Kubernetes学习系列
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
[root@k8s-master propertirs]# 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 [root@k8s-master propertirs]# cat /home/yaml/propertirs/ui.properties color.good=purple color.bad=yellow allow.textmode=true how.nice.to.look=fairlyNice [root@k8s-master propertirs]# kubectl create configmap game-config --from-file=/home/yaml/propertirs/ configmap "game-config" created [root@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： [root@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
[root@k8s-master propertirs]# 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 [root@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
[root@k8s-master propertirs]# kubectl create configmap game-config-3 --from-file=game-special-key=/home/yaml/propertirs/game.properties configmap "game-config-3" created [root@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
[root@k8s-master propertirs]# kubectl create configmap game-config-4 --from-literal=special.user=zhenyu --from-literal=special.passwd=yaodidiao configmap "game-config-4" created [root@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。
[root@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 [root@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" [root@k8s-master propertirs]# kubectl create -f testEnv.yaml pod "testenv" created [root@k8s-master propertirs]# kubectl exec -ti testenv sh / # echo $SPECIAL_USER zhenyu / #
2.2 挂载文件数据卷
[root@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 [root@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 [root@k8s-master propertirs]# kubectl create -f testVolume.yaml pod "testvolume" created [root@k8s-master propertirs]# kubectl exec -ti testvolume sh / # cd /etc/config/ /etc/config # ls game.properties ui.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
[root@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-4 [root@k8s-master propertirs]# kubectl get configmaps 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 [root@k8s-master propertirs]# kubectl create -f testVolume.yaml pod "testvolume" created [root@k8s-master propertirs]# kubectl exec -ti testvolume sh / # cd /etc/config/ /etc/config # ls special.passwd special.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。