一、Pod的配置管理
应用部署的一个最佳实践是将应用所需的配置信息和程序进行分离，这样就可以是应用程序被更好的服用，通过不同的配置也能实现更灵活的功能。ConfigMap允许将配置文件和镜像文件分离，以是容器化的应用程序具有可移植性。
二、ConfigMap概述
ConfigMap供容器使用的典型用法如下：
-
生成为容器内的环境变量
-
设置容器启动命令的启动参数（需设置为环境变量）
-
以volume的形式挂在为容器内部的文件或目录
ConfigMap以一个或多个key:value的形式保存在Kubernetes系统中供应用使用，即可以表示一个变量的值（apploglevel=info），也可以表示一个完整的配置文件的内容（server.xml=<?xml...>...）
三、创建ConfigMap资源对象
3.1 cm-appvars.yaml
apiVersion: v1 kind: ConfigMap metadata: name: cm-appvars data: apploglevel: info appdatadir: /var/data
创建ConfigMap
kubectl create -f cm-appvars.yaml
查看ConfigMap
kubectl get configmap NAME DATA AGE cm-appvars 2 12s kubectl describe configmap/cm-appvars Name: cm-appvars Namespace: default Labels: <none> Annotations: Data ==== appdatadir: ---- /var/data apploglevel: ---- info Events: <none> kubectl get configmap/cm-appvars -o yaml apiVersion: v1 data: appdatadir: /var/data apploglevel: info kind: ConfigMap metadata: annotations: kubectl.kubernetes.io/last-applied-configuration: | {"apiVersion":"v1","data":{"appdatadir":"/var/data","apploglevel":"info"},"kind":"ConfigMap","metadata":{"annotations":{},"name":"cm-appvars","namespace":"default"}} creationTimestamp: "2020-06-10T02:45:21Z" managedFields: - apiVersion: v1 fieldsType: FieldsV1 fieldsV1: f:data: .: {} f:appdatadir: {} f:apploglevel: {} f:metadata: f:annotations: .: {} f:kubectl.kubernetes.io/last-applied-configuration: {} manager: kubectl operation: Update time: "2020-06-10T02:45:21Z" name: cm-appvars namespace: default resourceVersion: "268969" selfLink: /api/v1/namespaces/default/configmaps/cm-appvars uid: e9f40932-d0de-4419-8e94-cc8941c20e6c
3.2 同一目录多个文件创建ConfigMap
分别设置key为配置文件别名，value则是配置文件文本内容
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
使用上述两个文件创建ConfigMap
# kubectl create configmap cm-appconfigfiles --from-file=/usr/local/k8s/configmap/configmapfiles/ configmap/cm-appconfigfiles created
查看创建的cm-appconfigfiles
# kubectl get configmap NAME DATA AGE cm-appconfigfiles 2 10s
# kubectl describe configmap cm-appconfigfiles Name: cm-appconfigfiles Namespace: default Labels: <none> Annotations: <none> Data ==== ui.properties: ---- color.good=purple color.bad=yellow allow.textmode=true how.nice.to.look=fairlyNice 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 Events: <none>
# kubectl get configmap cm-appconfigfiles -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: "2020-06-10T05:56:50Z" managedFields: - apiVersion: v1 fieldsType: FieldsV1 fieldsV1: f:data: .: {} f:game.properties: {} f:ui.properties: {} manager: kubectl operation: Update time: "2020-06-10T05:56:50Z" name: cm-appconfigfiles namespace: default resourceVersion: "283535" selfLink: /api/v1/namespaces/default/configmaps/cm-appconfigfiles uid: d3dbf64d-b381-47b6-9fc6-fbdc286f80c0
3.3 根据文字值创建ConfigMap
--from-literal
# kubectl create configmap cm-appenv --from-literal=loglevel=info --from-literal=appdatadir=/var/data
查看创建的configmap
# kubectl create configmap cm-appenv --from-literal=loglevel=info --from-literal=appdatadir=/var/data # kubectl get configmap NAME DATA AGE cm-appconfigfiles 2 7m42s cm-appenv 2 6s cm-appvars 2 3h19m kubectl describe configmap cm-appenv Name: cm-appenv Namespace: default Labels: <none> Annotations: <none> Data ==== appdatadir: ---- /var/data loglevel: ---- info Events: <none>
四、在Pod中使用ConfigMap
4.1 通过环境变量方式使用ConfigMap
以cm-appvars ConfigMap为例
apiVersion: v1 kind: ConfigMap metadata: name: cm-appvars data: apploglevel: info appdatadir: /var/data
在Pod “cm-test-pod”中，将ConfigMap “cm-appvars”中的内容以环境变量的方式设置为容器内部的环境变量
apiVersion: v1 kind: Pod metadata: name: cm-test-pod spec: containers: - name: cm-test image: busybox command: ["/bin/bash","-c","env|grep APP"] env: - name: APPLOGLEVEL valueFrom: configMapKeyRef: name: cm-appvars key: apploglevel - name: APPDATADIR valueFrom: configMapKeyRef: name: cm-appvars key: appdatadir restartPolicy: Never
查看容器环境变量
# kubectl logs cm-test-pod APPDATADIR=/var/data APPLOGLEVEL=info
4.2 envFrom
Kubernetes从1.6版本开始，引入一个新的字段envFrom，实现了在Pod环境中将ConfigMap中所有定义的key=value自动生成为环境变量
apiVersion: v1 kind: Pod metadata: name: cm-envfrom-pod spec: containers: - name: envfrom-test image: busybox command: ["sh","-c","env"] envFrom: - configMapRef: name: cm-appvars restartPolicy: Never
查看容器环境变量
# kubectl logs cm-envfrom-pod apploglevel=info KUBERNETES_SERVICE_PORT=443 KUBERNETES_PORT=tcp://10.96.0.1:443 HOSTNAME=cm-envfrom-pod MYWEB_PORT_8080_TCP_ADDR=10.111.193.215 MYWEB_SERVICE_HOST=10.111.193.215 SHLVL=1 HOME=/root MYWEB_PORT_8080_TCP_PORT=8080 MYWEB_PORT_8080_TCP_PROTO=tcp MYWEB_SERVICE_PORT=8080 MYWEB_PORT=tcp://10.111.193.215:8080 MYWEB_PORT_8080_TCP=tcp://10.111.193.215:8080 MYSQL_PORT_3306_TCP_ADDR=10.109.55.96 KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin KUBERNETES_PORT_443_TCP_PORT=443 MYSQL_PORT_3306_TCP_PORT=3306 MYSQL_SERVICE_HOST=10.109.55.96 MYSQL_PORT_3306_TCP_PROTO=tcp KUBERNETES_PORT_443_TCP_PROTO=tcp appdatadir=/var/data MYSQL_SERVICE_PORT=3306 MYSQL_PORT=tcp://10.109.55.96:3306 KUBERNETES_SERVICE_PORT_HTTPS=443 KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443 MYSQL_PORT_3306_TCP=tcp://10.109.55.96:3306 KUBERNETES_SERVICE_HOST=10.96.0.1 PWD=/