docker学习笔记---理解swarm集群

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理解swarm集群

一个swarm是一组运行docker服务器的的集群,docker服务器可以是物理机也可以是虚拟机.

swarm manager可以使用多种策略来运行容器.比如”emptiest node”—部署容器到压力最小的服务器上,或者”global”—确保每台服务器都只允许一个容器实例.你可以在Compose文件中指示swarm manager去选择何种策略

swarm managers是swarm进群中唯一可以执行命令,或者授权其他服务器以”workers”身份加入swarm集群的服务器.

初始化swarm,加入节点

试验环境:

1.10.0.0.50 —swarm manager
2.10.0.0.12 —worker 节点

  • 初始化swarm,并且指定通告的IP
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[root@localhost ~]$docker swarm init --advertise-addr 10.0.0.50
Swarm initialized: current node (zlvl9l94blu3rfcaaptdvo9u1) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-2i5fyjf2niw81tudcvpw33yuni277vz45lt6tyi5bvcnhvuwea-bj091dpe6e69ph9kt3lmsthgp 10.0.0.50:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

根据上面提示,在第二台服务器上以worker身份加入swarm集群

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[root@php ~]$docker swarm join --token SWMTKN-1-2i5fyjf2niw81tudcvpw33yuni277vz45lt6tyi5bvcnhvuwea-bj091dpe6e69ph9kt3lmsthgp 10.0.0.50:2377
This node joined a swarm as a worker.
[root@php ~]$

执行docker node ls命令可以管理和查看swarm集群的所有节点

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[root@localhost ~]$docker node ls
ID                            HOSTNAME                STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION
zlvl9l94blu3rfcaaptdvo9u1 *   localhost.localdomain   Ready               Active              Leader              18.09.2
ud5ztqzvvfwg3d3hwmts5y9ct     php                     Ready               Active                                  18.09.3
[root@localhost ~]$

执行docker swarm leave命令将某个节点退出swarm集群

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[root@php ~]$docker swarm leave
Node left the swarm.
[root@php ~]$

此时这个节点在swarm集群中状态为down

[root@localhost ~]$docker node ls
ID                            HOSTNAME                STATUS              AVAILABILITY        MANAGER STATUS      ENGINE VERSION
zlvl9l94blu3rfcaaptdvo9u1 *   localhost.localdomain   Ready               Active              Leader              18.09.2
ud5ztqzvvfwg3d3hwmts5y9ct     php                     Down                Active                                  18.09.3
[root@localhost ~]$

在swarm集群部署app

现在可以把上一小节的docker compose部署在swarm集群上了.执行命令和上一小节一样.但是需要注意的是只能在swarm manager节点服务器上执行命令.

在第一台服务器上执行如下命令:(确保docker compose文件和镜像文件在这台服务器上)

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root@localhost ~]$cd /data/compose
[root@localhost compose]$ls
docker-compose.yml
[root@localhost compose]$docker stack deploy -c docker-compose.yml getstartedlab
Creating network getstartedlab_webnet
Creating service getstartedlab_web
[root@localhost compose]$

APP已经成功部署到swarm集群上,现在可以使用上一小节中的同样的命令来管理app集群,只不过这次services和容器已经部署到两台服务器上:

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[root@localhost compose]$docker stack ps getstartedlab
ID                  NAME                      IMAGE                  NODE                    DESIRED STATE       CURRENT STATE              ERROR                              PORTS
4borwslue8k5        getstartedlab_web.1       friendlyhello:latest   localhost.localdomain   Running             Preparing 6 seconds ago
ixmkldh16otx        getstartedlab_web.2       friendlyhello:latest   php                     Ready               Preparing 22 seconds ago
i2yhimkst4iq         \_ getstartedlab_web.2   friendlyhello:latest   php                     Shutdown            Rejected 23 seconds ago    "No such image: friendlyhello:…"
gytqpcwnzvrm        getstartedlab_web.3       friendlyhello:latest   localhost.localdomain   Running             Preparing 6 seconds ago
j94tblo4qjwa        getstartedlab_web.4       friendlyhello:latest   php                     Ready               Preparing 22 seconds ago
b7r9xkf4glh6         \_ getstartedlab_web.4   friendlyhello:latest   php                     Shutdown            Rejected 22 seconds ago    "No such image: friendlyhello:…"
i8sv4c293ata        getstartedlab_web.5       friendlyhello:latest   localhost.localdomain   Running             Preparing 6 seconds ago

需要在另外一台服务器上pull同样的镜像,否则容器无法启动

  • 在第二台服务器上下载我阿里云私有仓库的镜像

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    docker login --username=jessehuang408 registry.cn-hangzhou.aliyuncs.com
    Password:

    [root@php ~]$docker pull registry.cn-hangzhou.aliyuncs.com/jesse_images/jesse_images:frendlyhello-v1.0
    frendlyhello-v1.0: Pulling from jesse_images/jesse_images
    f7e2b70d04ae: Pull complete
    1e9214730e83: Pull complete
    5bd4ec081f7b: Pull complete
    be26b369a1e7: Pull complete
    236be9d80905: Pull complete
    1bf8a3675b0b: Pull complete
    5752f9477f0c: Pull complete
    Digest: sha256:8e8b57ef6e22c8c04c1c80cfab9f336928cffabacaa4ae4e74ec57e54bcffdb2
    Status: Downloaded newer image for registry.cn-hangzhou.aliyuncs.com/jesse_images/jesse_images:frendlyhello-v1.0

    [root@php ~]$docker images
    REPOSITORY                                                    TAG                 IMAGE ID            CREATED             SIZE
    registry.cn-hangzhou.aliyuncs.com/jesse_images/jesse_images   frendlyhello-v1.0   f091d1bb803c        2 days ago          131MB
    [root@php ~]$*

  • 将镜像修改成和第一台服务器一样:frendlyhello:latest

命令:

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docker tag 镜像ID REPOSITORY:TAG
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[root@php ~]$docker tag f091d1bb803c frendlyhello:latest
[root@php ~]$docker images
REPOSITORY                                                    TAG                 IMAGE ID            CREATED             SIZE
frendlyhello                                                  latest              f091d1bb803c        2 days ago          131MB
registry.cn-hangzhou.aliyuncs.com/jesse_images/jesse_images   frendlyhello-v1.0   f091d1bb803c        2 days ago          131MB
[root@php ~]$
  • 将第一台服务器的docker-compose文件拷贝到同样的目录下
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[root@php ~]$mkdir /data/compose
[root@php ~]$scp root@10.0.0.50:/data/compose/docker-compose.yml /data/compose/
  • 回到第一台服务器上删除刚才创建的getstartedlab
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[root@localhost compose]$docker stack rm getstartedlab
Removing service getstartedlab_web
Removing network getstartedlab_webnet

[root@localhost compose]$docker stack ps getstartedlab
nothing found in stack: getstartedlab
  • 重新部署docker compose
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[root@localhost compose]$docker stack deploy -c docker-compose.yml getstartedlab
Creating network getstartedlab_webnet
Creating service getstartedlab_web
[root@localhost compose]$
  • 成功部署
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[root@localhost compose]$docker stack ps getstartedlab
ID                  NAME                  IMAGE                  NODE                    DESIRED STATE       CURRENT STATE              ERROR               PORTS
uqsj8mim0sac        getstartedlab_web.1   friendlyhello:latest   localhost.localdomain   Running             Preparing 3 seconds ago
shjiwlnj12sp        getstartedlab_web.2   friendlyhello:latest   php                     Running             Preparing 24 seconds ago
8sqllvgid8jp        getstartedlab_web.3   friendlyhello:latest   php                     Running             Preparing 24 seconds ago
v7fsecgcg504        getstartedlab_web.4   friendlyhello:latest   php                     Running             Preparing 24 seconds ago
np8utmyvk5px        getstartedlab_web.5   friendlyhello:latest   localhost.localdomain   Running             Preparing 3 seconds ago
[root@localhost compose]$

在第二台的worker节点上执行命令会提示失败:

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[root@php compose]$docker stack ps getstartedlab
Error response from daemon: This node is not a swarm manager. Worker nodes can't be used to view or modify cluster state. Please run this command on a manager node or promote the current node to a manager.
[root@php compose]$

现在,在两台服务器上都能访问刚才部署的app

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 huangyong@huangyong-Macbook-Pro  ~  curl http://10.0.0.12:4000
<h3>Hello World!</h3><b>Hostname:</b> 926f433b3896<br/><b>Visits:</b> <i>cannot connect to Redis, counter disabled</i>% 

huangyong@huangyong-Macbook-Pro  ~  curl http://10.0.0.50:4000
<h3>Hello World!</h3><b>Hostname:</b> 1535f17586ea<br/><b>Visits:</b> <i>cannot connect to Redis, counter disabled</i>%                                                            huangyong@huangyong-Macbook-Pro  ~ 

扩展app

扩展app还是直接编辑docker-compose.yml文件.然后重新docker stack deploy部署即可.

如果是需要将其他虚拟机或者物理服务器加入进swarm集群,就像第二台服务器一样使用docker swarm join命令加入即可,

停止swarm

命令:

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docker stack rm getstartedlab

总结

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# 初始化一个swarm集群

docker swarm init --advertise-addr IP

#加入到swarm集群
docker swarm join --token <token> <swarm manager IP>:<port>

#部署app
docker stack deploy -c docker-compose.yml <services name>
> note:在所有docker服务器节点上都需要有docker-compose.yml文件和相关镜像

# 查看services 
docker stack ps <services name>
docker services ls
docker stack ls

# 从swarm集群中删除 services

docker stack rm <service name>

# 删除swarm集群节点

docker swarm leave #worker节点
docker swarm leave --force #manager节点

本文标题:docker学习笔记---理解swarm集群

文章作者:Jesse

发布时间:2020年06月29日 - 11:06

最后更新:2020年06月29日 - 21:06

原始链接:https://jesse.top/2020/06/29/docker/docker官网学习-5.学习swarm集群/

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