其他容器編排排程工具會大談特談“輕應用”、“十二要素應用”，這樣就勢必會對企業級複雜應用做很大的改動。Kubernetes是為了解決“如何合理使用容器支撐企業級複雜應用”這個問題而誕生的，所以它的設計理念是要支援絕大多數應用的原生形態。例如，很多應用程式的配置需要通過配置檔案，命令列引數和環境變數的組合配置來完成（“十二要素應用”等均要求去配置）。這些配置應該從image內容中解耦，以此來保持容器化應用程式的可移植性。ConfigMap API資源提供了將配置資料注入容器的方式，同時保證該機制對容器來說是透明的。ConfigMap可以被用來儲存單個屬性，也可以用來儲存整個配置檔案或者JSON二進位制大物件。
ConfigMap API資源儲存鍵/值對配置資料，這些資料可以在pods裡使用。ConfigMap跟Secrets類似，但是ConfigMap可以更方便的處理不包含敏感資訊的字串。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
通過示例程式碼可以看到：ConfigMap可以包含細粒度的配置項，如：example.property.1；也可以包含粗粒度的配置檔案，如：example.property.file。
1、建立ConfigMap
1.1 從資料夾建立
[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 #該方法只能得到ConfigMap的Key和size Name: game-config Namespace: default Labels: <none> Annotations: <none> Data ==== ui.properties: 83 bytes game.properties: 158 bytes #若想得到詳細資訊，可通過以下命令： [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 從檔案建立
[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 指定具體的值
[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 環境變數或引數
建立一個Pod，並將一個已經建立好的ConfigMap作為環境變數，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 掛載檔案資料卷
[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 掛載資訊資料卷
[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 熱更新
當ConfigMap以資料卷的形式掛載進Pod的時，這時更新ConfigMap（或刪掉重建ConfigMap），Pod內掛載的配置資訊會熱更新。這時可以增加一些監測配置檔案變更的指令碼，然後reload對應服務。