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[TOC]

### （1）本文在[Docker----DockerSwarm集群环境搭建](http://blog.redrose2100.com/article/71) 的环境基础上
如下，有三个manager节点（192.168.145.128，192.168.145.129,192.168.145.130）和一个worker节点（192.168.145.131）
```bash
[root@localhost ~]# docker node ls
ID                            HOSTNAME                STATUS    AVAILABILITY   MANAGER STATUS   ENGINE VERSION
fhpe4p0m4gb47pxh48kf9psp8     localhost.localdomain   Ready     Active         Reachable        20.10.10
p1cfiyfyxgkhupjj03tvq40ph     localhost.localdomain   Ready     Active         Reachable        20.10.10
wsqaq4isrzhlgphnnaqxucy6r *   localhost.localdomain   Ready     Active         Leader           20.10.10
xlgi99te9cchyz9n3ydkycf6k     localhost.localdomain   Ready     Active                          20.10.10
[root@localhost ~]#
```
### （2）查看docker service 帮助文档
```bash
[root@localhost ~]# docker service --help

Usage:  docker service COMMAND

Manage services

Commands:
  create      Create a new service
  inspect     Display detailed information on one or more services
  logs        Fetch the logs of a service or task
  ls          List services
  ps          List the tasks of one or more services
  rm          Remove one or more services
  rollback    Revert changes to a service's configuration
  scale       Scale one or multiple replicated services
  update      Update a service

Run 'docker service COMMAND --help' for more information on a command.
[root@localhost ~]#
```
### （3）创建集群服务
如下，在一个manager集群节点上（192.168.145.128）创建一个Nginx集群服务，对外暴露端口8080，映射到内部80端口，设置副本数为2
```bash
[root@localhost ~]# docker service create --name nginx_service -p 8080:80 --replicas 2 nginx
j2jgvfdfyqgcsf1zcii23djul
overall progress: 2 out of 2 tasks
1/2: running   [==================================================>]
2/2: running   [==================================================>]
verify: Service converged
[root@localhost ~]#
```
### （4）查看已创建的集群服务

```bash
[root@localhost ~]# docker service ls
ID             NAME            MODE         REPLICAS   IMAGE          PORTS
j2jgvfdfyqgc   nginx_service   replicated   2/2        nginx:latest   *:8080->80/tcp
[root@localhost ~]#
```

### （5）查看已经创建的容器
如下，发现在192.168.145.128和192.168.145.129上分别启动了一个docker，这是因为设置了副本数为2

```bash
[root@localhost ~]# docker ps
CONTAINER ID   IMAGE          COMMAND                  CREATED         STATUS         PORTS     NAMES
c01d7f019abd   nginx:latest   "/docker-entrypoint.…"   4 minutes ago   Up 4 minutes   80/tcp    nginx_service.2.k3zo9jubllvv95muy3l4gydf3
[root@localhost ~]#
```
### （6）在浏览器访问，正常
![](/static/upload/20220503_143132.png)
### （7）动态扩容服务
在其中一个manager节点执行扩容操作，设置副本数为10
```bash
[root@localhost ~]# docker service update --replicas 10 nginx_service
nginx_service
overall progress: 10 out of 10 tasks
1/10: running   [==================================================>]
2/10: running   [==================================================>]
3/10: running   [==================================================>]
4/10: running   [==================================================>]
5/10: running   [==================================================>]
6/10: running   [==================================================>]
7/10: running   [==================================================>]
8/10: running   [==================================================>]
9/10: running   [==================================================>]
10/10: running   [==================================================>]
verify: Service converged
[root@localhost ~]#
```
### （8）查看各个节点docker数量
发现在各个节点上共创建了10个正常的docker，因为设置了副本数为10

```bash
[root@localhost ~]# docker service ps nginx_service
ID             NAME                  IMAGE          NODE                    DESIRED STATE   CURRENT STATE                     ERROR                              PORTS
u41u5xs2sx4u   nginx_service.1       nginx:latest   localhost.localdomain   Running         Running 47 seconds ago
jnyxv9jftpj5   nginx_service.2       nginx:latest   localhost.localdomain   Running         Running 3 seconds ago
s823t867u872   nginx_service.3       nginx:latest   localhost.localdomain   Running         Running 32 seconds ago
dshe3f5rfkza    \_ nginx_service.3   nginx:latest   localhost.localdomain   Shutdown        Failed 3 seconds ago              "error creating external conne…"
8r80ylbz4v8c    \_ nginx_service.3   nginx:latest   localhost.localdomain   Shutdown        Rejected 4 seconds ago            "error creating external conne…"
mwo0vxu9zd4d    \_ nginx_service.3   nginx:latest   localhost.localdomain   Shutdown        Failed 5 seconds ago              "error creating external conne…"
c8f19q3tge0s   nginx_service.4       nginx:latest   localhost.localdomain   Running         Running 4 seconds ago
01smx140ihm6   nginx_service.5       nginx:latest   localhost.localdomain   Running         Running less than a second ago
9onahdwcgfdg    \_ nginx_service.5   nginx:latest   localhost.localdomain   Shutdown        Rejected less than a second ago   "error creating external conne…"
ulr5ntbeqltz    \_ nginx_service.5   nginx:latest   localhost.localdomain   Shutdown        Rejected 13 seconds ago           "error creating external conne…"
c7rbpp5hcadx    \_ nginx_service.5   nginx:latest   localhost.localdomain   Shutdown        Failed 14 seconds ago             "error creating external conne…"
k8u10ncvdpje   nginx_service.6       nginx:latest   localhost.localdomain   Running         Running 33 seconds ago
n8rvtsglqrum    \_ nginx_service.6   nginx:latest   localhost.localdomain   Shutdown        Rejected 8 seconds ago            "error creating external conne…"
kfm79fl5773k    \_ nginx_service.6   nginx:latest   localhost.localdomain   Shutdown        Failed 9 seconds ago              "error creating external conne…"
ep3mz85cq42q    \_ nginx_service.6   nginx:latest   localhost.localdomain   Shutdown        Rejected 6 seconds ago            "error creating external conne…"
t53va7itdkj8   nginx_service.7       nginx:latest   localhost.localdomain   Running         Running 3 seconds ago
0uozqvv5gx9r   nginx_service.8       nginx:latest   localhost.localdomain   Running         Running 47 seconds ago
7u58boi8oppy   nginx_service.9       nginx:latest   localhost.localdomain   Running         Running less than a second ago
p1pzcqsgfaoo    \_ nginx_service.9   nginx:latest   localhost.localdomain   Shutdown        Failed less than a second ago     "error creating external conne…"
p34rm7b9309p    \_ nginx_service.9   nginx:latest   localhost.localdomain   Shutdown        Failed less than a second ago     "error creating external conne…"
1lgbmlxpnf32    \_ nginx_service.9   nginx:latest   localhost.localdomain   Shutdown        Rejected 14 seconds ago           "error creating external conne…"
yo0zcq4vej8i   nginx_service.10      nginx:latest   localhost.localdomain   Running         Running 47 seconds ago
[root@localhost ~]#
```

### （9）动态缩容
如下，设置副本数为4
```bash
[root@localhost ~]# docker service update --replicas 4 nginx_service
nginx_service
overall progress: 4 out of 4 tasks
1/4: running   [==================================================>]
2/4: running   [==================================================>]
3/4: running   [==================================================>]
4/4: running   [==================================================>]
verify: Service converged
[root@localhost ~]# 
```
### （10）查看各个节点docker数量
然后查看发现各个节点docker总数压缩为4个了

```bash
[root@localhost ~]# docker service ps nginx_service
ID             NAME                  IMAGE          NODE                    DESIRED STATE   CURRENT STATE             ERROR                              PORTS
zm51ipb5u3zk   nginx_service.1       nginx:latest   localhost.localdomain   Running         Running 14 minutes ago
k3zo9jubllvv   nginx_service.2       nginx:latest   localhost.localdomain   Running         Running 14 minutes ago
lfjg4kovkuu2    \_ nginx_service.2   nginx:latest   localhost.localdomain   Shutdown        Rejected 14 minutes ago   "error creating external conne…"
ph1p09dnzzol    \_ nginx_service.2   nginx:latest   localhost.localdomain   Shutdown        Rejected 14 minutes ago   "error creating external conne…"
twg01hlw9lge    \_ nginx_service.2   nginx:latest   localhost.localdomain   Shutdown        Rejected 14 minutes ago   "error creating external conne…"
6sccd1tvt8rq   nginx_service.3       nginx:latest   localhost.localdomain   Running         Running 4 minutes ago
y3lk71ay7tqn    \_ nginx_service.3   nginx:latest   localhost.localdomain   Shutdown        Rejected 4 minutes ago    "error creating external conne…"
7oqy4e593wo8    \_ nginx_service.3   nginx:latest   localhost.localdomain   Shutdown        Failed 4 minutes ago      "error creating external conne…"
97wxj8kyr4be   nginx_service.6       nginx:latest   localhost.localdomain   Running         Running 4 minutes ago
1hvkth5ioau2    \_ nginx_service.6   nginx:latest   localhost.localdomain   Shutdown        Rejected 4 minutes ago    "error creating external conne…"
svwo7uyxqomp    \_ nginx_service.6   nginx:latest   localhost.localdomain   Shutdown        Rejected 4 minutes ago    "error creating external conne…"
xv3ao9argjwo    \_ nginx_service.6   nginx:latest   localhost.localdomain   Shutdown        Rejected 4 minutes ago    "error creating external conne…"
sdsay83pvtz2    \_ nginx_service.6   nginx:latest   localhost.localdomain   Shutdown        Rejected 4 minutes ago    "error creating external conne…"
[root@localhost ~]#
```
### （11）如此便可实现集群服务的控台扩缩容了

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