Docker-compose至K8S迁移工具kompose

参考Github：
https://github.com/kubernetes/kompose
kompose工具用于将docker-compose配置文件转换的k8s可识别的yaml文件

1. 安装
   CentOS安装

# yum install epel-release
# yum install kompose

使用源安装的版本较老可直接下载

# Linux
curl -L https://github.com/kubernetes/kompose/releases/download/v1.32.0/kompose-linux-amd64 -o kompose

# macOS
curl -L https://github.com/kubernetes/kompose/releases/download/v1.32.0/kompose-darwin-amd64 -o kompose

chmod +x kompose
sudo mv ./kompose /usr/local/bin/kompose

查看版本

# kompose version
1.32.0 (765fde254)

2. 转换和使用k8s启动
   示例docker-compose.yml

# cat docker-compose.yml 
version: "2.0"
services:
  nginx:
    hostname: nginx
    image: nginx
    ports:
      - 83:80
    volumes:
    - ./html:/usr/share/nginx/html 

该示例使用nginx镜像启动并且挂载一个首页index.htmt

# cat html/index.html 
Hello Kompose

可以使用以下命令启动

# docker-compose up -d

访问

转换成k8s可识别的yaml文件
如果yml文件名不是docker-compose.yml则加参数-f 文件名进行转换

# kompose convert
WARN Volume mount on the host "/data/softs/kompose/html" isn't supported - ignoring path on the host 
INFO Kubernetes file "nginx-service.yaml" created 
INFO Kubernetes file "nginx-deployment.yaml" created 
INFO Kubernetes file "nginx-claim0-persistentvolumeclaim.yaml" created 

会在当前文件夹生成deployment,pvc,service文件

不能直接使用kubelet apply部署而是需要修改
pvc文件需要修改增加创建该pvc使用的storageclass
使用以下命令获取当时集群的storageclass，如果无storageclass则需要先创建

# kubectl get storageclass
NAME                          PROVISIONER               AGE
gluster-heketi-storageclass   kubernetes.io/glusterfs   66d
managed-nfs-storage           fuseim.pri/ifs            76d

修改后的pvc文件如下

# cat nginx-claim0-persistentvolumeclaim.yaml 
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  labels:
    io.kompose.service: nginx-claim0
  name: nginx-claim0
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: gluster-heketi-storageclass
  resources:
    requests:
      storage: 100Mi

在原始内容基础新增一行指定pvc使用的stoageclass

先生成pvc

# kubectl apply -f nginx-claim0-persistentvolumeclaim.yaml 
persistentvolumeclaim/nginx-claim0 created

查看

# kubectl get pvc nginx-claim0
NAME           STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS                  AGE
nginx-claim0   Bound    pvc-2f0bd9e0-c562-11ee-a9a9-525400e71cb5   1Gi        RWO            gluster-heketi-storageclass   29s

应用deployment文件部署deployment

# cat nginx-deployment.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  annotations:
    kompose.cmd: kompose convert
    kompose.version: 1.32.0 (765fde254)
  labels:
    io.kompose.service: nginx
  name: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      io.kompose.service: nginx
  strategy:
    type: Recreate
  template:
    metadata:
      annotations:
        kompose.cmd: kompose convert
        kompose.version: 1.32.0 (765fde254)
      labels:
        io.kompose.network/kompose-default: "true"
        io.kompose.service: nginx
    spec:
      containers:
        - image: nginx
          name: nginx
          ports:
            - containerPort: 80
              hostPort: 83
              protocol: TCP
          volumeMounts:
            - mountPath: /usr/share/nginx/html
              name: nginx-claim0
      hostname: nginx
      restartPolicy: Always
      volumes:
        - name: nginx-claim0
          persistentVolumeClaim:
            claimName: nginx-claim0

# kubectl apply -f nginx-deployment.yaml 
deployment.apps/nginx created

查看部署的pod

# kubectl get pod nginx-5d7ccd9d5-mqm92
NAME                    READY   STATUS    RESTARTS   AGE
nginx-5d7ccd9d5-mqm92   1/1     Running   0          2m1s

把首页拷贝到对应文件夹即可在node节点使用pod地址访问

# kubectl cp html/index.html nginx-5d7ccd9d5-mqm92:/usr/share/nginx/html

部署服务

# kubectl apply -f nginx-service.yaml 
service/nginx created
[root@CentOS7K8SMaster01063 kompose]# cat nginx-service.yaml 
apiVersion: v1
kind: Service
metadata:
  annotations:
    kompose.cmd: kompose convert
    kompose.version: 1.32.0 (765fde254)
  labels:
    io.kompose.service: nginx
  name: nginx
spec:
  ports:
    - name: "83"
      port: 83
      targetPort: 80
  selector:
    io.kompose.service: nginx

部署

# kubectl apply -f nginx-service.yaml 
service/nginx created

查看

# kubectl get svc nginx
NAME    TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
nginx   ClusterIP   10.0.0.20    <none>        83/TCP    60s

默认生成的svc为ClusetrIP模式即只能在集群内访问
在node节点访问，注意本次把port修改为83了即集群ip的83端口对应pod的80端口

# curl 10.0.0.20:83
Hello Kompose

修改service配置文件修改成nodeport
修改后如下

# cat nginx-service.yaml 
apiVersion: v1
kind: Service
metadata:
  annotations:
    kompose.cmd: kompose convert
    kompose.version: 1.32.0 (765fde254)
  labels:
    io.kompose.service: nginx
  name: nginx
spec:
  ports:
    - name: "83"
      port: 80
      targetPort: 80
  type: NodePort 
  selector:
    io.kompose.service: nginx

修改以下两处

应用svc文件

# kubectl apply -f nginx-service.yaml 
service/nginx configured

查看svc

# kubectl get svc nginx
NAME    TYPE       CLUSTER-IP   EXTERNAL-IP   PORT(S)        AGE
nginx   NodePort   10.0.0.20    <none>        80:32858/TCP   7m23s

在Node内使用ClusterIP访问

# curl 10.0.0.20

在集群外使用任意nodeip+随机的nodeport端口访问

# curl 192.168.3.65:32858

实验完毕删除deployment pvc svc

# kubectl delete -f nginx-deployment.yaml 
# kubectl delete -f nginx-claim0-persistentvolumeclaim.yaml 
# kubectl delete -f nginx-service.yaml 

注意事项

1. 如果在docker-compose中有设置容器的重启策略为on-failer则需要修改成always否则转换后不是deployment而是pod
2. 如果docker-compose中有挂载配置文件则也会生成对应的pvc配置文件，可以删除对应配置修改成configmap的挂载方式
3. 默认转换的service为clusterip格式如有需要则修改成NodePort格式
4. 默认转换后的pvc文件是没有stoeageclass信息，需要手动添加