部署服务
我们使用 docker service 命令来管理 Swarm 集群中的服务，该命令只能在管理节点运行。
新建服务
现在我们在上一节创建的 Swarm 集群中运行一个名为 nginx 服务。
$ docker service create --replicas 3 -p 80:80 --name nginx nginx:1.19.0-alpine
参数说明：
- --replicas：service运行的实例个数
- --name: 命名service为nginx
现在我们使用浏览器，输入任意节点 IP ，即可看到 nginx 默认页面。
查看服务
使用 docker service ls 来查看当前 Swarm 集群运行的服务。
[root@node1 ~]$ docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
ryhf4p7z48tc nginx replicated 3/3 nginx:1.19.0-alpine *:80->80/tcp
使用 docker service ps 来查看某个服务的详情。
[root@node1 ~]$ docker service ps nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
ibgbksjwo1kx nginx.1 nginx:1.19.0-alpine node1 Running Running 3 minutes ago
g46e327d7j9g nginx.2 nginx:1.19.0-alpine node2 Running Running 3 minutes ago
uyxa5ye0061k nginx.3 nginx:1.19.0-alpine node3 Running Running 3 minutes ago
使用 docker service logs 来查看某个服务的日志。
[root@node1 ~]$ docker service logs nginx
nginx.2.g46e327d7j9g@node1 | /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
nginx.2.g46e327d7j9g@node1 | /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
nginx.2.g46e327d7j9g@node1 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
nginx.2.g46e327d7j9g@node1 | 10-listen-on-ipv6-by-default.sh: Getting the checksum of /etc/nginx/conf.d/default.conf
nginx.2.g46e327d7j9g@node1 | 10-listen-on-ipv6-by-default.sh: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
nginx.2.g46e327d7j9g@node1 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
nginx.2.g46e327d7j9g@node1 | /docker-entrypoint.sh: Configuration complete; ready for start up
nginx.2.g46e327d7j9g@node1 | 10.0.0.2 - - [28/Jun/2020:07:39:37 +0000] "GET / HTTP/1.1" 200 612 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36" "-"
nginx.2.g46e327d7j9g@node1 | 2020/06/28 07:39:37 [error] 29#29: *1 open() "/usr/share/nginx/html/favicon.ico" failed (2: No such file or directory), client: 10.0.0.2, server: localhost, request: "GET /favicon.ico HTTP/1.1", host: "172.16.35.10", referrer: "http://172.16.35.10/"
nginx.2.g46e327d7j9g@node1 | 10.0.0.2 - - [28/Jun/2020:07:39:37 +0000] "GET /favicon.ico HTTP/1.1" 404 555 "http://172.16.35.10/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36" "-"
nginx.1.ibgbksjwo1kx@node2 | /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
nginx.1.ibgbksjwo1kx@node2 | /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
nginx.1.ibgbksjwo1kx@node2 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
nginx.1.ibgbksjwo1kx@node2 | 10-listen-on-ipv6-by-default.sh: Getting the checksum of /etc/nginx/conf.d/default.conf
nginx.1.ibgbksjwo1kx@node2 | 10-listen-on-ipv6-by-default.sh: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
nginx.1.ibgbksjwo1kx@node2 | /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
nginx.1.ibgbksjwo1kx@node2 | /docker-entrypoint.sh: Configuration complete; ready for start up
nginx.1.ibgbksjwo1kx@node2 | 10.0.0.3 - - [28/Jun/2020:07:39:43 +0000] "GET / HTTP/1.1" 200 612 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36" "-"
nginx.1.ibgbksjwo1kx@node2 | 2020/06/28 07:39:43 [error] 29#29: *2 open() "/usr/share/nginx/html/favicon.ico" failed (2: No such file or directory), client: 10.0.0.3, server: localhost, request: "GET /favicon.ico HTTP/1.1", host: "172.16.35.11", referrer: "http://172.16.35.11/"
nginx.1.ibgbksjwo1kx@node2 | 10.0.0.3 - - [28/Jun/2020:07:39:43 +0000] "GET /favicon.ico HTTP/1.1" 404 555 "http://172.16.35.11/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.116 Safari/537.36" "-"
service缩容与扩容
我们可以使用 docker service scale 对一个服务运行的容器数量进行伸缩。
当业务处于高峰期时，我们需要扩展服务运行的容器数量。
[root@node1 ~]$ docker service scale nginx=5
nginx scaled to 5
overall progress: 5 out of 5 tasks
1/5: running [==================================================>]
2/5: running [==================================================>]
3/5: running [==================================================>]
4/5: running [==================================================>]
5/5: running [==================================================>]
verify: Service converged
当业务平稳时，我们需要减少服务运行的容器数量。
[root@node1 ~]$ docker service scale nginx=2
nginx scaled to 2
overall progress: 2 out of 2 tasks
1/2: running [==================================================>]
2/2: running [==================================================>]
verify: Service converged
删除service
使用 docker service rm 来从 Swarm 集群移除某个服务。
[root@node1 ~]$ docker service rm nginx
nginx