创建 Docker Swarm 集群

初始化集群（在第一个管理节点操作）

docker swarm init --advertise-addr <first_manager_node_ip>

部分输出信息：

Swarm initialized: current node (mo2p7vnjhzg68g6wzejozdomo) is now a manager.

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

    docker swarm join --token SWMTKN-1-260gjixktxw5jnso7osrpuhsvqi33m2ksro78doxlqanug9kix-141p1sm3ugjsw4qh6o0ydp2ho <first_manager_node_ip>:2377    ## 此命令添加worker节点

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.    ## 此方法可获取添加备用manager节点的命令，生产环境必须至少三个manager节点

后面可以使用以下命令获取加入其他节点的命令：

docker swarm join-token manager
docker swarm join-token worker

集群节点之间打开协议和端口说明：

TCP port 2377 for cluster management communications
TCP and UDP port 7946 for communication among nodes
UDP port 4789 for overlay network traffic

查看集群状态：

docker info
docker node ls

部署一个服务（必须在管理节点操作）

部署命令：

# docker service create --replicas 1 --name helloworld alpine ping docker.com

命令说明：

The docker service create command creates the service.
The --name flag names the service helloworld.
The --replicas flag specifies the desired state of 1 running instance.
The arguments alpine ping docker.com define the service as an Alpine Linux container that executes the command ping docker.com.

查看服务：

# docker service ls

ID                  NAME                MODE                REPLICAS            IMAGE               PORTS
9wquw4g6bt29        helloworld          replicated          1/1                 alpine:latest

# docker service inspect --pretty helloworld

ID:             9wquw4g6bt29yl213t4pg9spq
Name:           helloworld
Service Mode:   Replicated
 Replicas:      1
Placement:
UpdateConfig:
 Parallelism:   1
 On failure:    pause
 Monitoring Period: 5s
 Max failure ratio: 0
 Update order:      stop-first
RollbackConfig:
 Parallelism:   1
 On failure:    pause
 Monitoring Period: 5s
 Max failure ratio: 0
 Rollback order:    stop-first
ContainerSpec:
 Image:         alpine:latest@sha256:7df6db5aa61ae9480f52f0b3a06a140ab98d427f86d8d5de0bedab9b8df6b1c0
 Args:          ping docker.com 
Resources:
Endpoint Mode:  vip

# docker service ps helloworld

ID                  NAME                IMAGE               NODE                DESIRED STATE       CURRENT STATE            ERROR               PORTS
f5tbcczzpy40        helloworld.1        alpine:latest       mysqlmaster         Running             Running 34 minutes ago

扩容服务：

# docker service scale helloworld=3

helloworld 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 helloworld

ID                  NAME                IMAGE               NODE                DESIRED STATE       CURRENT STATE            ERROR               PORTS
f5tbcczzpy40        helloworld.1        alpine:latest       mysqlmaster         Running             Running 40 minutes ago                       
pbx26pn67shp        helloworld.2        alpine:latest       mysqlmaster         Running             Running 20 seconds ago                       
d7k1txanj0d2        helloworld.3        alpine:latest       mysqlslave          Running             Running 20 seconds ago

删除服务：

# docker service rm helloworld