kubernetes存储（一）——K8S的Configmap配置管理（4种创建方式+使用）

参考官网：https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/

1.ConfigMap配置管理介绍

ConfigMap配置管理
• Configmap用于保存配置数据，以键值对形式存储。
• configMap 资源提供了向 Pod 注入配置数据的方法。
• 旨在让镜像和配置文件解耦，以便实现镜像的可移植性和可复用性。

典型的使用场景
• 填充环境变量的值
• 设置容器内的命令行参数
• 填充卷的配置文件

---

2.创建ConfigMap的4种方式

创建ConfigMap的方式有4种：
• 使用字面值创建
• 使用文件创建
• 使用目录创建
• 编写configmap的yaml文件创建

2.1 使用字面值创建ConfigMap

kubectl create configmap my-config --from-literal=key1=config1 --from-literal=key2=config2

[kubeadm@server1 ~]$ mkdir cm
[kubeadm@server1 ~]$ ls
calico.yaml  cm  kube-flannel.yml  mainfest  nginx.tar
[kubeadm@server1 ~]$ cd cm/
[kubeadm@server1 cm]$ kubectl create configmap my-config --from-literal=key1=config1 --from-literal=key2=config2
configmap/my-config created
[kubeadm@server1 cm]$ kubectl get cm
NAME        DATA   AGE
my-config   2      10s
[kubeadm@server1 cm]$ kubectl get cm -n kube-system 
NAME                                 DATA   AGE
coredns                              1      8d
extension-apiserver-authentication   6      8d
kube-flannel-cfg                     2      21h
kube-proxy                           2      8d
kubeadm-config                       2      8d
kubelet-config-1.18                  1      8d
[kubeadm@server1 cm]$ kubectl describe cm my-config 
Name:         my-config
Namespace:    default
Labels:       <none>
Annotations:  <none>
Data
====
key1:
----
config1
key2:
----
config2
Events:  <none>

---

2.2 使用文件创建ConfigMap

kubectl create configmap my-config-2 --from-file=/etc/resolv.conf

[kubeadm@server1 cm]$ kubectl create configmap my-config-2 --from-file=/etc/resolv.conf 
configmap/my-config-2 created
[kubeadm@server1 cm]$ kubectl get cm
NAME          DATA   AGE
my-config     2      2m51s
my-config-2   1      3s
[kubeadm@server1 cm]$ kubectl describe cm my-config-2
Name:         my-config-2
Namespace:    default
Labels:       <none>
Annotations:  <none>
Data
====
resolv.conf:
----
nameserver 114.114.114.114
Events:  <none>

---

2.3 使用目录创建ConfigMap

kubectl create configmap my-config-3 --from-file=test

[kubeadm@server1 cm]$ mkdir test
[kubeadm@server1 cm]$ cp /etc/fstab test/
[kubeadm@server1 cm]$ cp /etc/resolv.conf test/
[kubeadm@server1 cm]$ ll test/
total 8
-rw-r--r-- 1 kubeadm kubeadm 502 Jun 27 19:47 fstab
-rw-rw-r-- 1 kubeadm kubeadm  28 Jun 27 19:47 resolv.conf
[kubeadm@server1 cm]$  kubectl create configmap my-config-3 --from-file=test 
configmap/my-config-3 created
[kubeadm@server1 cm]$ kubectl get cm
NAME          DATA   AGE
my-config     2      5m50s
my-config-2   1      3m2s
my-config-3   2      6s
[kubeadm@server1 cm]$ kubectl describe cm my-config-3
Name:         my-config-3
Namespace:    default
Labels:       <none>
Annotations:  <none>
Data
====
fstab:
----
#
# /etc/fstab
# Created by anaconda on Thu May  7 08:28:06 2020
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=8d5190d9-d50b-49f4-a64e-7a985e53dc81 /                       xfs     defaults        0 0
UUID=60910b20-bbdc-4701-bba3-a9760086a1a0 /boot                   xfs     defaults        0 0
#UUID=2a714265-f92d-4429-87da-9f09e32e6ff2 swap                    swap    defaults        0 0
resolv.conf:
----
nameserver 114.114.114.114
Events:  <none>

---

2.4 编写configmap的yaml文件创建ConfigMap

[kubeadm@server1 cm]$ vim cm1.yml
[kubeadm@server1 cm]$ cat cm1.yml
apiVersion: v1 
kind: ConfigMap 
metadata:  
  name: cm1-config 
data:  
  db_host: "172.25.0.250"  
  db_port: "3306"
[kubeadm@server1 cm]$ kubectl apply -f cm1.yml 
configmap/cm1-config created
[kubeadm@server1 cm]$ kubectl get cm
NAME          DATA   AGE
cm1-config    2      10s
my-config     2      172m
my-config-2   1      169m
my-config-3   2      166m
[kubeadm@server1 cm]$ kubectl describe cm cm1-config 
Name:         cm1-config
Namespace:    default
Labels:       <none>
Annotations:  
Data
====
db_host:
----
172.25.0.250
db_port:
----
3306
Events:  <none>

---

3.使用configmap

如何使用configmap：
• 通过环境变量的方式直接传递给pod
• 通过在pod的命令行下运行的方式
• 作为volume的方式挂载到pod内

3.1 使用configmap设置环境变量

示例一：重新定义configmap的key

[kubeadm@server1 cm]$ vim cm1.yml 
[kubeadm@server1 cm]$ cat cm1.yml 
apiVersion: v1 
kind: ConfigMap 
metadata:  
  name: cm1-config 
data:  
  db_host: "172.25.0.250"  
  db_port: "3306"
---
apiVersion: v1 
kind: Pod 
metadata:  
  name: pod1 
spec:  
  containers:    
    - name: pod1      
      image: busybox      
      command: ["/bin/sh", "-c", "env"]       
      env:        
        - name: key1          
          valueFrom:            
            configMapKeyRef:              
              name: cm1-config              
              key: db_host        
        - name: key2          
          valueFrom:            
            configMapKeyRef:              
             name: cm1-config              
             key: db_port  
  restartPolicy: Never
[kubeadm@server1 cm]$ kubectl apply -f cm1.yml 
configmap/cm1-config unchanged
pod/pod1 created
[kubeadm@server1 cm]$ kubectl get cm
NAME          DATA   AGE
cm1-config    2      7m31s
my-config     2      179m
my-config-2   1      176m
my-config-3   2      173m
[kubeadm@server1 cm]$ kubectl describe cm cm1-config 
Name:         cm1-config
Namespace:    default
Labels:       <none>
Annotations:  
Data
====
db_host:
----
172.25.0.250
db_port:
----
3306
Events:  <none>
[kubeadm@server1 cm]$ kubectl logs pod1 
KUBERNETES_PORT=tcp://10.96.0.1:443
KUBERNETES_SERVICE_PORT=443
HOSTNAME=pod1
SHLVL=1
HOME=/root
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
key1=172.25.0.250
KUBERNETES_PORT_443_TCP_PROTO=tcp
key2=3306
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
KUBERNETES_SERVICE_HOST=10.96.0.1
PWD=/

---

示例二:直接使用configmap

[kubeadm@server1 cm]$ vim cm1.yml 
[kubeadm@server1 cm]$ cat cm1.yml 
apiVersion: v1 
kind: ConfigMap 
metadata:  
  name: cm1-config 
data:  
  db_host: "172.25.0.250"  
  db_port: "3306"
---
apiVersion: v1 
kind: Pod 
metadata:  
  name: pod1 
spec:  
  containers:    
    - name: pod1      
      image: busybox      
      command: ["/bin/sh", "-c", "env"]       
      envFrom:        
        - configMapRef:            
            name: cm1-config        
  restartPolicy: Never
[kubeadm@server1 cm]$ kubectl delete pod pod1
pod "pod1" deleted
[kubeadm@server1 cm]$ kubectl apply -f cm1.yml 
configmap/cm1-config unchanged
pod/pod1 created
[kubeadm@server1 cm]$ kubectl logs pod1 
KUBERNETES_PORT=tcp://10.96.0.1:443
KUBERNETES_SERVICE_PORT=443
HOSTNAME=pod1
SHLVL=1
db_port=3306
HOME=/root
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
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
KUBERNETES_SERVICE_HOST=10.96.0.1
PWD=/
db_host=172.25.0.250

---

3.2 使用conigmap设置命令行参数

[kubeadm@server1 cm]$ kubectl delete pod pod1
pod "pod1" deleted
[kubeadm@server1 cm]$ cat cm1.yml 
apiVersion: v1 
kind: ConfigMap 
metadata:  
  name: cm1-config 
data:  
  db_host: "172.25.0.250"  
  db_port: "3306"
---
apiVersion: v1 
kind: Pod 
metadata:  
  name: pod1 
spec:  
  containers:    
    - name: pod1      
      image: busybox      
      command: ["/bin/sh", "-c", "echo $(db_host) $(db_port)"] 
      envFrom:        
        - configMapRef:            
            name: cm1-config        
  restartPolicy: Never
[kubeadm@server1 cm]$ kubectl apply -f cm1.yml 
configmap/cm1-config unchanged
pod/pod1 created
[kubeadm@server1 cm]$ kubectl logs pod1 
172.25.0.250 3306

---

3.3 通过数据卷使用configmap

示例一

[kubeadm@server1 cm]$ kubectl delete pod pod1
pod "pod1" deleted
[kubeadm@server1 cm]$ vim cm1.yml 
[kubeadm@server1 cm]$ cat cm1.yml 
apiVersion: v1 
kind: ConfigMap 
metadata:  
  name: cm1-config 
data:  
  db_host: "172.25.0.250"  
  db_port: "3306"
---
apiVersion: v1 
kind: Pod 
metadata:  
  name: pod1 
spec:  
  containers:    
    - name: pod1      
      image: busybox      
      command: ["/bin/sh", "-c", "cat /config/*"]
      volumeMounts:      
      - name: config-volume        
        mountPath: /config  
  volumes:    
    - name: config-volume      
      configMap:        
        name: cm1-config  
  restartPolicy: Never
[kubeadm@server1 cm]$ kubectl apply -f cm1.yml 
configmap/cm1-config unchanged
pod/pod1 created
[kubeadm@server1 cm]$ kubectl logs pod1 
172.25.0.2503306  

---

示例二

[kubeadm@server1 cm]$ kubectl delete pod pod1
pod "pod1" deleted
[kubeadm@server1 cm]$ vim cm1.yml 
[kubeadm@server1 cm]$ cat cm1.yml 
apiVersion: v1 
kind: ConfigMap 
metadata:  
  name: cm1-config 
data:  
  db_host: "172.25.0.250"  
  db_port: "3306"
---
apiVersion: v1 
kind: Pod 
metadata:  
  name: pod1 
spec:  
  containers:    
    - name: pod1      
      image: nginx      
      volumeMounts:      
      - name: config-volume        
        mountPath: /config  
  volumes:    
    - name: config-volume      
      configMap:        
        name: cm1-config  
[kubeadm@server1 cm]$ kubectl apply -f cm1.yml 
configmap/cm1-config unchanged
pod/pod1 created
[kubeadm@server1 cm]$ kubectl exec -it pod1 -- bash
root@pod1:/# cd /config/
root@pod1:/config# ls
db_host  db_port
root@pod1:/config# cat db_host 
172.25.0.250root@pod1:/config# cat db_port 
3306root@pod1:/config# exit

[kubeadm@server1 cm]$ kubectl describe cm cm1-config 
Name:         cm1-config
Namespace:    default
Labels:       <none>
Annotations:  
Data
====
db_host:
----
172.25.0.250
db_port:
----
3306
Events:  <none>
[kubeadm@server1 cm]$ kubectl edit cm cm1-config
configmap/cm1-config edited
[kubeadm@server1 cm]$ kubectl describe cm cm1-config 
Name:         cm1-config
Namespace:    default
Labels:       <none>
Annotations:  
Data
====
db_host:
----
172.25.0.254
db_port:
----
3306
Events:  <none>

Pod数据并不会实时更新，需要等待几秒

---

3.4 configmap热更新

[kubeadm@server1 cm]$ vim cm1.yml 
[kubeadm@server1 cm]$ cat cm1.yml 
apiVersion: v1 
kind: ConfigMap 
metadata:  
  name: cm1-config 
data:  
  db_host: "172.25.0.250"  
  db_port: "3306"
---
apiVersion: apps/v1 
kind: Deployment 
metadata:  
  name: my-nginx 
spec:  
  replicas: 1  
  selector:    
    matchLabels:      
      app: nginx  
  template:    
    metadata:      
      labels:        
        app: nginx    
    spec:      
      containers:        
        - name: nginx          
          image: nginx          
          ports:          
          - containerPort: 80          
          volumeMounts:          
          - name: config-volume            
            mountPath: /etc/nginx/conf.d
      volumes:        
        - name: config-volume          
          configMap:            
            name: nginx-config

[kubeadm@server1 cm]$ vim server.conf
[kubeadm@server1 cm]$ cat server.conf
server {    
 listen       8000;    
 server_name  _;
    
 location / {        
  root /usr/share/nginx/html;        
  index  index.html index.htm;    
        }
}
[kubeadm@server1 cm]$  kubectl create configmap nginx-config --from-file=server.conf
configmap/nginx-config created
[kubeadm@server1 cm]$ kubectl describe cm nginx-config 
Name:         nginx-config
Namespace:    default
Labels:       <none>
Annotations:  <none>
Data
====
server.conf:
----
server {    
  listen       8000;    
  server_name  _;
    
  location / {        
    root /usr/share/nginx/html;        
    index  index.html index.htm;    
        }
}
Events:  <none>
[kubeadm@server1 cm]$ kubectl apply -f cm1.yml
configmap/cm1-config created
deployment.apps/my-nginx created
[kubeadm@server1 cm]$ kubectl get pod
NAME                        READY   STATUS    RESTARTS   AGE
my-nginx-7db4c4f989-pl6c8   1/1     Running   0          3s
[kubeadm@server1 cm]$ kubectl get pod -o wide
NAME                        READY   STATUS    RESTARTS   AGE   IP            NODE      NOMINATED NODE   READINESS GATES
my-nginx-7db4c4f989-pl6c8   1/1     Running   0          30s   10.244.1.70   server2   <none>           <none>
[kubeadm@server1 cm]$ curl 10.244.1.70
curl: (7) Failed connect to 10.244.1.70:80; Connection refused
[kubeadm@server1 cm]$ curl 10.244.1.70:8000
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>

[kubeadm@server1 cm]$ kubectl exec my-nginx-7db4c4f989-pl6c8 -- cat /etc/nginx/conf.d/server.conf
server {    
 listen       8000;    
 server_name  _;
    
 location / {        
  root /usr/share/nginx/html;        
  index  index.html index.htm;    
        }
}

修改端口号

[kubeadm@server1 cm]$ kubectl edit cm nginx-config 
configmap/nginx-config edited
[kubeadm@server1 cm]$ kubectl exec my-nginx-7db4c4f989-pl6c8 -- cat /etc/nginx/conf.d/server.conf
server {    
 listen       8080;    
 server_name  _;
    
 location / {        
  root /usr/share/nginx/html;        
  index  index.html index.htm;    
        }
}
[kubeadm@server1 cm]$ kubectl get pod -o wide
NAME                        READY   STATUS    RESTARTS   AGE    IP            NODE      NOMINATED NODE   READINESS GATES
my-nginx-7db4c4f989-pl6c8   1/1     Running   0          6m2s   10.244.1.70   server2   <none>           <none>
[kubeadm@server1 cm]$ curl 10.244.1.70:8000
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>

可以看出configmap热更新以生效,但访问Pod的8080端口是无效的
手动触发pod滚动更新
kubectl patch deployments.apps my-nginx --patch '{"spec": {"template": {"metadata": {"annotations": {"version/config": "20200219"}}}}}'