一：简介很多生产环境中的应用程序配置较为复杂，可能需要多个config文件、命令行参数和环境变量的组合。使用容器部署时，把配置应该从应用程序镜像中解耦出来，以保证镜像的可移植性。
ConfigMap是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让我们能够从容器镜像中把配置的详细信息给解耦出来。通过ConfigMap我们能够把配置以key-value对的形式传递到container或者别的系统组件（比如Controller）里面。
二：ConfigMap的创建方式1.From Literal Values 可以用kubectl create来创建一个ConfigMap,然后通过kubectl get来获取
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# Create the ConfigMap
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$ kubectl create configmap my-config --from-literal=key1=value1 --from-literal=key2=value2
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configmap"my-config" created
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# Get the ConfigMap Details for my-config
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$ kubectl get configmaps my-config -o yaml
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apiVersion: v1
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data:
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key1: value1
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key2: value2
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kind: ConfigMap
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metadata:
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creationTimestamp: 2017-05-31T07:21:55Z
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name: my-config
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namespace: default
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resourceVersion: "241345"
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selfLink: /api/v1/namespaces/default/configmaps/my-config
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uid: d35f0a3d-45d1-11e7-9e62-080027a46057
2.From Configuration File 直接通过配置文件来创建
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: special-config
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namespace: default
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data:
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special.how: very
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apiVersion: v1
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kind: ConfigMap
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metadata:
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name: env-config
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namespace: default
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data:
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log_level: INFO
3. 当前目录下包含如果有配置文件donkey.properties 可以通过kubectl命令创建一个包含该文件内容的ConfigMap
kubectl create configmap donkey.properties --from-file=donkey.properties
三：ConfigMap的使用方式1.Pod 通过env使用ConfigMap定义环境变量
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apiVersion: v1
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kind: Pod
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metadata:
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name: dapi-test-pod
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spec:
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containers:
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- name: test-container
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image: gcr.io/google_containers/busybox
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command: ["/bin/sh", "-c", "env" ]
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env:
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- name: SPECIAL_LEVEL_KEY
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valueFrom:
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configMapKeyRef:
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name: special-config
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key: special.how
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- name: LOG_LEVEL
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valueFrom:
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configMapKeyRef:
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name: env-config
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key: log_level
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restartPolicy: Never
从Kubernetes V1.6 开始，引入一个新的字段envFrom，实现在Pod环境内将ConfigMap中所以定义的key=value自动生成环境变量：
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apiVersion: v1
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kind: Pod
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metadata:
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name: dapi-test-pod
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spec:
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containers:
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- name: test-container
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image: gcr.io/google_containers/busybox
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command: [ "/bin/sh", "-c", "env" ]
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envFrom:
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- configMapRef:
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name: special-config
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restartPolicy: Never
2.使用ConfigMap设置容器启动命令的启动参数
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apiVersion: v1
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kind: Pod
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metadata:
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name: dapi-test-pod
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spec:
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containers:
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- name: test-container
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image: k8s.gcr.io/busybox
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command: ["/bin/sh", "-c", "echo $(SPECIAL_LEVEL_KEY) $(SPECIAL_TYPE_KEY)" ]
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env:
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- name: SPECIAL_LEVEL_KEY
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valueFrom:
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configMapKeyRef:
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name: special-config
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key: SPECIAL_LEVEL
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- name: SPECIAL_TYPE_KEY
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valueFrom:
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configMapKeyRef:
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name: special-config
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key: SPECIAL_TYPE
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restartPolicy: Never
3.在存储卷中使用ConfigMap
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apiVersion: v1
kind: Pod
metadata:
name: busybox
namespace: default
spec:
containers:
- image: 120.79.156.135/desktop/busybox:latest
command:
- sleep
- "3600"
imagePullPolicy: IfNotPresent
name: busybox
volumeMounts:
- name: donkeyconfig
mountPath: /configfiles
volumes:
- name: donkeyconfig
configMap:
name: donkey.properties
items:
- key: donkey.properties
path: donkey.properties
restartPolicy: Always
imagePullSecrets:
- name: registry-secret
四：使用ConfigMap的限制条件
1.ConfigMap必须在Pod之前创建
2.ConfigMap受Namespace限制，只有处于相同Namespaces中的Pod可以引用它
3.ConfigMap 中的配额管理还未能实现
4.kubelet只支持可以被API Server管理的Pod使用ConfigMap
网页名称：kubernetes实践之三十五：Pod配置管理ConfigMap
网页路径：
http://www.cdkjz.cn/article/pepghp.html
