docker 容器入门（四）

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写在前面的话

每篇一句

桃李不言，下自成蹊。

利用docker-compose.yml 构建整套可伸缩的服务

docker-compose.yml是一种YAML文件，定义了容器的一系列完整的行为。

docker-compose.yml

docker-compose.yml定义了如下步骤：

  • 从远程仓库拉取镜像
  • 运行3个容器实例作为web服务，并限制每个容器运行10%CPU，50MB内存
  • 将web容器的80端口映射到宿主机的8080端口
  • web容器通过webnet进行负载均衡
  • webnet使用默认的负载均衡overlay设置
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    version: "3"
    services:
      web:
        # replace username/repo:tag with your name and image details
       #image: username/repo:tag
        image: zakizqzhang/get-started:20171028
        deploy:
          replicas: 3
          resources:
            limits:
              cpus: "0.1"
              memory: 50M
          restart_policy:
            condition: on-failure
        ports:
          - "8080:80"
        networks:
          - webnet
    networks:
      webnet:

运行web负载均衡服务

swarm初始化

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[root@localhost docker]# docker swarm  init
Swarm initialized: current node (qmjxu1mlwksrxfwyq1sgcerrw) is now a manager.
To add a worker to this swarm, run the following command:
    docker swarm join --token SWMTKN-1-5rww1e0vi13ye8blfyt6oq6nzd3cbfxlc22f3xt1ga93g6apjr-0pgu4dk6fkq3nw7kuu5urzp4k 10.254.36.124:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

假设有第2台宿主机要加入只需运行,刚初始化的第一台默认为manager

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docker swarm join --token SWMTKN-1-5rww1e0vi13ye8blfyt6oq6nzd3cbfxlc22f3xt1ga93g6apjr-0pgu4dk6fkq3nw7kuu5urzp4k 10.254.36.124:2377

web服务运行

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[root@localhost docker]# docker stack deploy  -c docker-compose.yml  testapp
Creating network testapp_webnet
Creating service testapp_web
[root@localhost docker]# netstat -tlunp |grep 8080
tcp6       0      0 :::8080                 :::*                    LISTEN      4013/dockerd        
[root@localhost docker]# docker service ls
ID                  NAME                MODE                REPLICAS            IMAGE                              PORTS
0qbok4qrbv13        testapp_web         replicated          3/3

验证运行了3个容器

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[root@localhost docker]# docker ps
CONTAINER ID        IMAGE                              COMMAND             CREATED             STATUS              PORTS               NAMES
a16ea7161064        zakizqzhang/get-started:20171028   "python app.py"     33 seconds ago      Up 32 seconds       80/tcp              testapp_web.1.caohbftrljwcd5r2oh1c4l4rj
52d904f5aedd        zakizqzhang/get-started:20171028   "python app.py"     34 seconds ago      Up 33 seconds       80/tcp              testapp_web.2.viroif27tho9kyl4u7joko9tw
62f6ea377033        zakizqzhang/get-started:20171028   "python app.py"     37 seconds ago      Up 36 seconds       80/tcp              testapp_web.3.7au0dpwv8tdh1t9of1fcstqt6

浏览器访问，默认轮询方式负载到后端容器

查看testapp运行的容器

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[root@localhost docker]# docker service ps testapp
ID                  NAME                IMAGE                              NODE                    DESIRED STATE       CURRENT STATE            ERROR               PORTS
caohbftrljwc        testapp_web.1       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 11 minutes ago                       
viroif27tho9        testapp_web.2       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 11 minutes ago                       
7au0dpwv8tdh        testapp_web.3       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 11 minutes ago

扩容成5个容器,运行testapp web服务

将replicas 后面3改成5,重新deploy,docker stack rm 关闭testapp应用。

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[root@localhost docker]# docker container  ls -q
fce3c2f3d922
9d73cdd1b15a
9b5234fd0ac2
[root@localhost docker]# docker stack  ls
NAME                SERVICES
testapp             1
[root@localhost docker]# docker stack rm testapp
Removing service testapp_web
Removing network testapp_webnet
[root@localhost docker]# vi docker-compose.yml 
[root@localhost docker]# docker stack deploy  -c docker-compose.yml  testapp
Creating network testapp_webnet
Creating service testapp_web
[root@localhost docker]# docker service ps testapp
ID                  NAME                IMAGE                              NODE                    DESIRED STATE       CURRENT STATE            ERROR               PORTS
i423v1euglfh        testapp_web.1       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 29 seconds ago                       
r4nsghgl6sv3        testapp_web.2       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 29 seconds ago                       
rlrtevdw49df        testapp_web.3       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 29 seconds ago                       
jhcaukbhyrv3        testapp_web.4       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 29 seconds ago                       
lc3jhwhrugn3        testapp_web.5       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 29 seconds ago

swarms集群

上面虽然实现了负载均衡，但是5个容器都运行在一台host上，下面我们通过swarms集群将testapp应用运行在2台host上。
刚刚第一台主机ip为：10.254.36.124
第二天主机ip 为10.254.36.42

10.254.36.42 加入swarms集群

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root@ubuntu:~# docker swarm join --token SWMTKN-1-5rww1e0vi13ye8blfyt6oq6nzd3cbfxlc22f3xt1ga93g6apjr-0pgu4dk6fkq3nw7kuu5urzp4k 10.254.36.124:2377
This node joined a swarm as a worker.

查看目前加入的节点情况

在第一台manager上运行，后加入的worker节点查看不了。

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[root@localhost docker]# docker node  ls
ID                            HOSTNAME                STATUS              AVAILABILITY        MANAGER STATUS
gtb0ip6zpu4hazqg4bgp5z19m     ubuntu                  Ready               Active              
qmjxu1mlwksrxfwyq1sgcerrw *   localhost.localdomain   Ready               Active              Leader

重新运行,注意要在第二台机器先拉取镜像，不然运行失败。

10.254.36.42

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root@ubuntu:~# docker pull zakizqzhang/get-started:20171028 
20171028: Pulling from zakizqzhang/get-started
85b1f47fba49: Pull complete 
a5e401c4a903: Pull complete 
9f744658dd62: Pull complete 
562843cc69f8: Pull complete 
361ab7a9bb73: Pull complete 
72c3035db3bc: Pull complete 
68e97c9c12b4: Pull complete 
Digest: sha256:208754af6f21fc4a14eacc22b2734f490cb3c3a495c7595a74a79529f68429ee
Status: Downloaded newer image for zakizqzhang/get-started:20171028

10.254.36.124

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[root@localhost docker]# docker stack rm  testapp 
Removing service testapp_web
Removing network testapp_webnet
[root@localhost docker]# docker stack deploy  -c docker-compose.yml  testapp
Creating network testapp_webnet
Creating service testapp_web
[root@localhost docker]# docker stack  ps testapp
ID                  NAME                IMAGE                              NODE                    DESIRED STATE       CURRENT STATE            ERROR               PORTS
2pybph62tyfd        testapp_web.1       zakizqzhang/get-started:20171028   ubuntu                  Running             Running 5 seconds ago                        
36gqfjvz23zw        testapp_web.2       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 29 seconds ago                       
r35bc1sihxre        testapp_web.3       zakizqzhang/get-started:20171028   ubuntu                  Running             Running 2 seconds ago                        
nt00z4ykjhrm        testapp_web.4       zakizqzhang/get-started:20171028   localhost.localdomain   Running             Running 28 seconds ago                       
09d742ecerbp        testapp_web.5       zakizqzhang/get-started:20171028   ubuntu                  Running             Running 3 seconds ago

到现在testapp应用的web服务，高可用就妥妥的了，随便一台host宕机，不会影响对外服务。

----纸上得来终觉浅绝知此事要躬行----
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