【Docker】docker swarm集群搭建和相关命令分享
Docker swarm 集群通过 docker cli 来创建，并通过docker cli来实现应用的部署和集群的管理。
Docker swarm集群的搭建相对简单，这里使用三台虚拟机（一个管理节点，两个worker节点）来简单演示下集群的搭建过程。
|-----------------------------------------------------------------|
| hostname | IP |
|-----------------------------------------------------------------|
| master | 192.168.223.31 |
|-----------------------------------------------------------------|
| node-01 | 192.168.223.32 |
|-----------------------------------------------------------------|
| node-02 | 192.168.223.33 |
|-----------------------------------------------------------------|
虚拟机和docker-ce的安装这里就不做赘述了，安装后关闭系统默认的防火墙，关闭selinux，安装最新的docker-ce-20.10.17，并且修改docker.service，增加下面的参数配置。
# vi /lib/systemd/system/docker.service
在 ExecStart=/usr/bin/dockerd 后添加 -H tcp://0.0.0.0:2375 -H unix://var/run/docker.sock ,修改后的配置如下所示
[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix://var/run/docker.sock -H fd:// --containerd=/run/containerd/containerd.sock
修改后，记得reload配置，并且重启docker服务
# systemctl daemon-reload
# systemctl restart docker.service下面就给大家直接贴出我搭建和使用swarm集群过程的相关命令的记录。
---初始化集群的管理节点
# docker swarm init --advertise-addr 192.168.223.31
Swarm initialized: current node (betygbmft1wkh4kmrf5wx45mc) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-66syvw9yv8xr457lk4eviixyhd5fviw1gg3ktkwa1nkdp2rb44-14530poeryamdfwlssfynmxhk 192.168.223.31:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
---从节点加入到管理节点
# docker swarm join --token SWMTKN-1-66syvw9yv8xr457lk4eviixyhd5fviw1gg3ktkwa1nkdp2rb44-14530poeryamdfwlssfynmxhk 192.168.223.31:2377
This node joined a swarm as a worker.
----查看集群的节点、状态
# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
betygbmft1wkh4kmrf5wx45mc * master Ready Active Leader 20.10.17
nq4urvgyfdjedabze9p5oll6q node-01 Ready Active 20.10.17
t6wtou7b5jm07qltlrp35ha85 node-02 Ready Active 20.10.17
---创建网络
# docker network create --opt encrypted --driver overlay --attachable webnet
7e0huckau0g8olzsyvdts8ta2
---创建nginx服务（1）
# docker service create --replicas 2 --network webnet --name nginx --publish published=80,target=80 nginx:1.22.0
gf8n3ad4k1pkxqwej6xpdthhe
overall progress: 2 out of 2 tasks
1/2: running [==================================================>]
2/2: running [==================================================>]
verify: Service converged
or
---创建nginx服务（2）
# docker service create --replicas 3 --network webnet --name nginx -p 80:80 nginx:1.22.0
or
---创建nginx服务（3）- 仅允许在非manager节点上运行创建的服务，即只能在node节点上运行服务的副本
# docker service create --replicas 3 --constraint node.role!=manager --network webnet --name nginx -p 80:80 nginx:1.22.0
---查看服务信息
# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
gf8n3ad4k1pk nginx replicated 2/2 nginx:1.22.0 *:80->80/tcp
---查看nginx进程
# docker service ps nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
4vxulka6ofd2 nginx.1 nginx:1.22.0 master Running Running about a minute ago
res3qre7ywcx nginx.2 nginx:1.22.0 node-01 Running Running 3 minutes ago
---查看服务明细
# docker service inspect nginx
---服务扩展
# docker service scale nginx=3
nginx scaled to 3
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
# docker service ps nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
4vxulka6ofd2 nginx.1 nginx:1.22.0 master Running Running 10 minutes ago
res3qre7ywcx nginx.2 nginx:1.22.0 node-01 Running Running 11 minutes ago
xpwlus8bbo6z nginx.3 nginx:1.22.0 node-02 Running Running 25 seconds ago
---删除服务
# docker service rm nginx
nginx使用docker stack deploy部署portainer-ce和portainer-agent，已实现对swarm集群的监控、展示。
首先，我们在master节点和node节点上先pull需要的镜像
# docker pull portainer/portainer-ce
Using default tag: latest
latest: Pulling from portainer/portainer-ce
772227786281: Pull complete
96fd13befc87: Pull complete
35fb5a8b85ea: Pull complete
6665edb137b0: Pull complete
Digest: sha256:f716a714e6cdbb04b3f3ed4f7fb2494ce7eb4146e94020e324b2aae23e3917a9
Status: Downloaded newer image for portainer/portainer-ce:latest
docker.io/portainer/portainer-ce:latest
# docker pull portainer/agent:2.14.0
2.14.0: Pulling from portainer/agent
772227786281: Already exists
96fd13befc87: Already exists
3902c362cca3: Pull complete
a215b10008ab: Pull complete
434a8ea542bc: Pull complete
c1c68f189caa: Pull complete
Digest: sha256:8440499b6e1cda88442cf6c58c7fb6bad317708b796a747604ce76f65cc788ba
Status: Downloaded newer image for portainer/agent:2.14.0
docker.io/portainer/agent:2.14.0
# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
portainer/portainer-ce latest e8e975c3a7f0 6 days ago 278MB
portainer/agent 2.14.0 25e2624e6d49 6 days ago 166MB
nginx 1.22.0 b3c5c59017fb 10 days ago 142MB
第二步，编写portainer-agent-stack.yml文件
version: '3.2'
services:
agent:
image: portainer/agent:latest
volumes:
- /var/run/docker.sock:/var/run/docker.sock
- /var/lib/docker/volumes:/var/lib/docker/volumes
networks:
- agent_network
deploy:
mode: global
placement:
constraints: [node.platform.os == linux]
portainer:
image: portainer/portainer-ce:2.14.0
command: -H tcp://tasks.agent:9001 --tlsskipverify
ports:
- "9443:9443"
- "9000:9000"
- "8000:8000"
volumes:
- portainer_data:/data
networks:
- agent_network
deploy:
mode: replicated
replicas: 1
placement:
constraints: [node.role == manager]
networks:
agent_network:
driver: overlay
attachable: true
volumes:
portainer_data:备注：上面yml文件中的constraints字段的值，即node.role == manager，来限制portainer服务仅允许运行在swarm集群的管理节点上。
第三步，部署、启动portainer-ce和portainer-agent
# docker stack deploy -c portainer-agent-stack.yml portainer
Creating network portainer_agent_network
Creating service portainer_agent
Creating service portainer_portainer
# docker stack ls
NAME SERVICES ORCHESTRATOR
portainer 2 Swarm
# docker stack ps portainer
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
y66nxsac6of4 portainer_agent.betygbmft1wkh4kmrf5wx45mc portainer/agent:2.14.0 master Running Running 11 seconds ago
91uog63d7mth portainer_agent.nq4urvgyfdjedabze9p5oll6q portainer/agent:2.14.0 node-01 Running Running 12 seconds ago
eahaqvm3gyzc portainer_agent.t6wtou7b5jm07qltlrp35ha85 portainer/agent:2.14.0 node-02 Running Running 11 seconds ago
wy03vu1phwdq portainer_portainer.1 portainer/portainer-ce:latest master Running Running 8 seconds ago 部署、运行成功之后，我们可以通过下面的地址来访问portainer-ce的管理页面。
https://192.168.223.31:9443/
首次登录，需要在登录页面输入一个不少于12位的密码，以创建登录用户。在主页面我们可以看到系统的一个概况。
查看swarm集群的信息
修改集群节点的状态，可以暂停节点，也可以驱逐当前节点，默认是Active状态。
集群可视化（Cluster Visualizer）：
禁止在Manager节点创建Nginx服务后的Visualizer，可以发现Nginx服务只在Node节点上启动和运行了。
Docker swarm集群的特性：
1）当swarm集群所有节点关机后重启，重启后，之前创建的服务都可以自动启动；
2）当swarm集群某个从节点宕机，从节点上运行的容器会在其他节点上启动，以确保replicas设置的副本数不变；
3）当swarm集群只有一个主节点，且该主节点宕机，那么主节点上运行的服务，不会在从节点上再启动，replicas指定的服务副本数将无法得到保障；
4）当集群的主节点先启动的时候，有可能所有的副本都会在主节点上启动（如下所示，3个replicas全部在master节点上启动了），这时候我们为了使node节点的资源被合理利用，就需要将主节点上的多余的节点stop，之后被stop的节点就会在其他的node节点上均衡启动。由此我们可以得出一个结论，在启动swarm集群服务器时，最好先启动node节点，然后再启动master节点，这样可以使得管理节点创建的服务可以均衡的分布到node节点和master节点。
[root@master ~]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ba190e2c7691 nginx:1.22.0 "/docker-entrypoint.…" 27 seconds ago Up 20 seconds 80/tcp nginx.3.6ift78belu1ypa22qt3ib5tcu
3a79485f8638 nginx:1.22.0 "/docker-entrypoint.…" 28 seconds ago Up 20 seconds 80/tcp nginx.1.l3k4csim2kii8552k1wyg0dq4
33812961a987 nginx:1.22.0 "/docker-entrypoint.…" 28 seconds ago Up 20 seconds 80/tcp nginx.2.mplcqurndpu8h6fw8ml8nj6cs
参考：
https://cloud.tencent.com/developer/article/2025737
https://docs.docker.com/engine/reference/commandline/swarm_init/
https://docs.docker.com/engine/reference/commandline/swarm_join/