理解ConfigMap
ConfigMap允许您将配置文件从容器镜像中解耦，从而增强容器应用的可移植性。
ConfigMap API resource将配置数据以键值对的形式存储。这些数据可以在pod中消费或者为系统组件提供配置，例如controller。ConfigMap与Secret类似，但是通常只保存不包含敏感信息的字符串。用户和系统组件可以以同样的方式在ConfigMap中存储配置数据。
注意：ConfigMap只引用属性文件，而不会替换它们。可以把ConfigMap联想成Linux中的/etc目录和它里面的内容。例如，假如您使用ConfigMap创建了Kubernetes Volume，ConfigMap中的每个数据项都代表该volume中的一个文件。
ConfigMap相当于配置中心,用于Pod读取配置,避免每次只因为修改一个参数而升级镜像
ConfigMap必须在Pod之前被创建,
如果ConfigMap定义了Namespace, 则只有相同的Namespace的Pod才可以使用。
命令行创建configMap语法:
# kubectl create configmap myConfig --from-literal= --help
# 用指定的键（而不是磁盘上的文件基名称）创建名为my config的新configmap
kubectl create configmap my-config --from-file=key1=/path/to/bar/file1.txt --from-file=key2=/path/to/bar/file2.txt
# 使用key1=config1和key2=config2创建名为my config的新configMap
kubectl create configmap my-config --from-literal=key1=config1 --from-literal=key2=config2
# 从文件中的key=value对创建一个名为my config的新configmap
kubectl create configmap my-config --from-file=path/to/bar
# 从env文件创建名为my config的新configmap
kubectl create configmap my-config --from-env-file=path/to/bar.env
创建一个名为nginx-config的configMap,在命令行中给定键和值
[root@master configMap]# kubectl create configmap nginx-config --from-literal=server_port=80 --from-literal=server_name=baiyongjie.com
configmap/nginx-config created
[root@master configMap]# kubectl get configmaps
NAME DATA AGE
nginx-config 2 31s
[root@master configMap]# kubectl describe configmaps nginx-config
Name: nginx-config
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
server_name:
----
baiyongjie.com
server_port:
----
80
Events: <none>
通过文件创建configmap
[root@master configMap]# ls nginx-blog/www.conf
nginx-blog/www.conf
[root@master configMap]# cat nginx-blog/www.conf
server {
server_name blog.baiyongjie.com;
listen 80;
root /usr/local/nginx/html;
}
[root@master configMap]# kubectl create configmap nginx-blog --from-file=nginx-blog/www.conf
configmap/nginx-blog created
[root@master configMap]# kubectl describe configmaps nginx-blog
Name: nginx-blog
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
www.conf:
----
server {
server_name blog.baiyongjie.com;
listen 80;
root /usr/local/nginx/html;
}
Events: <none>
yaml文件创建configMap
[root@master configmaps]# cat volume-configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: configmap-test
namespace: default
data:
name: baiyongjie
sex: man
在Pod中使用ConfigMap,作为容器的启动参数
# 定义ConfigMap资源
[root@master configmaps]# cat volume-configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: configmap-test #ConfigMap名称,在pod中需要用到
namespace: default
data:
name: baiyongjie
sex: man
age: "26"
[root@master configmaps]# kubectl apply -f volume-configmap.yaml
configmap/configmap-test created
[root@master configmaps]# kubectl describe configmaps configmap-test
Name: configmap-test
Namespace: default
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","data":{"age":"26","name":"baiyongjie","sex":"man"},"kind":"ConfigMap","metadata":{"annotations":{},"name":"configmap-t...
Data
====
name:
----
baiyongjie
sex:
----
man
age:
----
26
Events: <none>
# 定义Pod资源
[root@master configmaps]# vim pod-configmap.yml
apiVersion: v1
kind: Pod
metadata:
name: configmap-test-pod
spec:
containers:
- name: configmap-test-pod
image: busybox
imagePullPolicy: IfNotPresent
command: ["/bin/sh","-c", "while true; do echo $(date) Name: $(name) Sex: $(sex) Age: $(age); sleep 5;done"] #每五秒输出一次定义的变量, 为了观察方便写成了while循环
env:
- name: name
valueFrom:
configMapKeyRef:
name: configmap-test
key: name
- name: sex
valueFrom:
configMapKeyRef:
name: configmap-test
key: sex
- name: age
valueFrom:
configMapKeyRef:
name: configmap-test
key: age
[root@master configmaps]# kubectl apply -f pod-configmap.yml
pod/configmap-test-pod created
# 可以看到ConfigMap中定义的变量已经被引用了
[root@master configmaps]# kubectl logs -f configmap-test-pod
Wed Mar 27 08:22:54 UTC 2019 Name: baiyongjie Sex: man Age: 26
Wed Mar 27 08:22:59 UTC 2019 Name: baiyongjie Sex: man Age: 26
Wed Mar 27 08:23:04 UTC 2019 Name: baiyongjie Sex: man Age: 26
Wed Mar 27 08:23:09 UTC 2019 Name: baiyongjie Sex: man Age: 26
在Pod中使用ConfigMap,当做卷挂载
# cat pod-configmap-volume.yml
apiVersion: v1
kind: Pod
metadata:
name: configmap-test-pod
spec:
containers:
- name: configmap-test-pod
image: nginx
imagePullPolicy: IfNotPresent
volumeMounts:
- name: config-volume
mountPath: /etc/config/configmap
readOnly: true
volumes:
- name: config-volume
configMap:
name: configmap-test
# kubectl apply -f pod-configmap.yml
pod/configmap-test-pod created
# kubectl exec -it configmap-test-pod -- /bin/bash
root@configmap-test-pod:/# cd /etc/config/configmap/
root@configmap-test-pod:/etc/config/configmap# ls -l
total 0
lrwxrwxrwx. 1 root root 10 Mar 28 02:01 age -> ..data/age
lrwxrwxrwx. 1 root root 11 Mar 28 02:01 name -> ..data/name
lrwxrwxrwx. 1 root root 10 Mar 28 02:01 sex -> ..data/sex
root@configmap-test-pod:/etc/config/configmap# for i in `ls /etc/config/configmap*`;do cat $i;echo ; done
26
baiyongjie
man
将ConfigMap中的键对挂载到Pod当文件使用
# 准备html文件
# cat index.html
<html>
<meta http-equiv="refresh" content="0;url=https://baiyongjie.com">
</html>
# 创建ConfigMap,从文件中导入,key为test.html
# kubectl create configmap configmap-nginx --from-file=test.html=index.html
configmap/configmap-nginx created
# 查看ConfigMap详细信息
# kubectl describe configmaps configmap-nginx
Name: configmap-nginx
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
test.html:
----
<html>
<meta http-equiv="refresh" content="0;url=https://baiyongjie.com">
</html>
# 定义Pod资源
# cat pod-configmap-volume-file.yaml
apiVersion: v1
kind: Pod
metadata:
name: configmap-test-pod-file
spec:
containers:
- name: configmap-test-pod-file
image: nginx
imagePullPolicy: IfNotPresent
volumeMounts:
- name: config-volume-nginx
mountPath: /usr/share/nginx/html/
readOnly: true
volumes:
- name: config-volume-nginx
configMap:
name: configmap-nginx
# 启动pod
# kubectl apply -f pod-configmap-volume-file.yaml
pod/configmap-test-pod-file created
# 查看启动后pod的IP地址
[root@master nginx-configmaps]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
configmap-test-pod-file 1/1 Running 0 30s 10.244.0.245 master <none> <none>
# 进入pod查看文件是否被挂载
# kubectl exec -it configmap-test-pod-file -- /bin/bash
root@configmap-test-pod-file:/# ls -l /usr/share/nginx/html/
total 0
lrwxrwxrwx. 1 root root 16 Mar 28 02:57 test.html -> ..data/test.html
# 查看挂载的文件内容
root@configmap-test-pod-file:/# cat /usr/share/nginx/html/test.html
<html>
<meta http-equiv="refresh" content="0;url=https://baiyongjie.com">
</html>
# 请求pod中挂载的test.html,查看效果
# curl 10.244.0.245/test.html
<html>
<meta http-equiv="refresh" content="0;url=https://baiyongjie.com">
</html>
将ConfigMap中的所有键值对配置为Pod环境变量
# vim pod-configmap-env.yml
apiVersion: v1
kind: Pod
metadata:
name: configmap-test-pod-env
spec:
containers:
- name: configmap-test-pod-env
image: busybox
imagePullPolicy: IfNotPresent
command: ["/bin/sh","-c","env"]
envFrom:
- configMapRef:
name: configmap-test
# kubectl apply -f pod-configmap-env.yml
pod/configmap-test-pod-env created
# kubectl logs configmap-test-pod-env |grep -E "name|sex|age"
age=26
sex=man
name=baiyongjie
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