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:1.13.7-alpine

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。

$ docker service ls
ID                  NAME                MODE                REPLICAS            IMAGE                 PORTS
kc57xffvhul5        nginx               replicated          3/3                 nginx:1.13.7-alpine   *:80->80/tcp

使用 docker service ps 来查看某个服务的详情。

$ docker service ps nginx
ID                  NAME                IMAGE                 NODE                DESIRED STATE       CURRENT STATE                ERROR               PORTS
pjfzd39buzlt        nginx.1             nginx:1.13.7-alpine   swarm2              Running             Running about a minute ago
hy9eeivdxlaa        nginx.2             nginx:1.13.7-alpine   swarm1              Running             Running about a minute ago
36wmpiv7gmfo        nginx.3             nginx:1.13.7-alpine   swarm3              Running             Running about a minute ago

使用 docker service logs 来查看某个服务的日志。

$ docker service logs nginx
nginx.3.36wmpiv7gmfo@swarm3    | 10.255.0.4 - - [25/Nov/2017:02:10:30 +0000] "GET / HTTP/1.1" 200 612 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:58.0) Gecko/20100101 Firefox/58.0" "-"
nginx.3.36wmpiv7gmfo@swarm3    | 10.255.0.4 - - [25/Nov/2017:02:10:30 +0000] "GET /favicon.ico HTTP/1.1" 404 169 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:58.0) Gecko/20100101 Firefox/58.0" "-"
nginx.3.36wmpiv7gmfo@swarm3    | 2017/11/25 02:10:30 [error] 5#5: *1 open() "/usr/share/nginx/html/favicon.ico" failed (2: No such file or directory), client: 10.255.0.4, server: localhost, request: "GET /favicon.ico HTTP/1.1", host: "192.168.99.102"
nginx.1.pjfzd39buzlt@swarm2    | 10.255.0.2 - - [25/Nov/2017:02:10:26 +0000] "GET / HTTP/1.1" 200 612 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:58.0) Gecko/20100101 Firefox/58.0" "-"
nginx.1.pjfzd39buzlt@swarm2    | 10.255.0.2 - - [25/Nov/2017:02:10:27 +0000] "GET /favicon.ico HTTP/1.1" 404 169 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:58.0) Gecko/20100101 Firefox/58.0" "-"
nginx.1.pjfzd39buzlt@swarm2    | 2017/11/25 02:10:27 [error] 5#5: *1 open() "/usr/share/nginx/html/favicon.ico" failed (2: No such file or directory), client: 10.255.0.2, server: localhost, request: "GET /favicon.ico HTTP/1.1", host: "192.168.99.101"

服务伸缩

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。

$ docker service scale nginx=5

当业务平稳时，我们需要减少服务运行的容器数量。

$ docker service scale nginx=2

删除服务

使用 docker service rm 来从 Swarm 集群移除某个服务。

$ docker service rm nginx