服务管理
服务和任务
任务 （Task）是 Swarm 中的最小的调度单位，目前来说就是一个单一的容器。
服务 （Services） 是指一组任务的集合，服务定义了任务的属性。服务有两种模式：
- replicated services 按照一定规则在各个工作节点上运行指定个数的任务
- global services 每个工作节点上运行一个任务
- 两种模式通过 docker service create 的 --mode 参数指定。
创建服务
docker service create --replicas 2 --name lotus busybox tail -F /var/log/dmesg
列出/过滤服务
列出服务
root@node-40:~# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
iwnj041mw0xn hello replicated 2/2 busybox:latest
n7e2zj2f8i9r lotus replicated 2/2 busybox:latest
如果Service过多可以通过-f指定参数以过滤服务
root@node-40:~# docker service ls -f "name=lotus"
ID NAME MODE REPLICAS IMAGE PORTS
n7e2zj2f8i9r lotus replicated 2/2 busybox:latest
列出/过滤任务(Task)
之前说道了一个Service会包含一个或多个容器，可以通过ps参数查看容器的状态，这里的容器称之为Task
root@node-40:~# docker service ps lotus
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
wqi3c5gs6q48 lotus.1 busybox:latest node-50 Running Running 3 minutes ago
6sxidbxzgkwu lotus.2 busybox:latest node-60 Running Running 3 minutes ago
过滤Task
root@node-40:~# docker service ps -f "node=node-50" lotus
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
wqi3c5gs6q48 lotus.1 busybox:latest node-50 Running Running 3 minutes ago
扩容/缩容服务
通过scale指令可以很方便的一个Service进行扩容或者缩容
root@node-40:~# docker service scale lotus=3
lotus scaled to 3
root@node-40:~# docker service ps lotus
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
wqi3c5gs6q48 lotus.1 busybox:latest node-50 Running Running 4 minutes ago
6sxidbxzgkwu lotus.2 busybox:latest node-60 Running Running 4 minutes ago
5lgzysyxjp4a lotus.3 busybox:latest node-50 Running Running 3 seconds ago
获取服务详细信息
第一种返回Json，第二种便于阅读
root@node-40:~# docker service inspect hello
root@node-40:~# docker service inspect hello --pretty
滚动/间隔更新
root@node-40:~# docker service create --replicas 2 --name redis --update-delay 10s redis:3.0.6
root@node-40:~# docker service update --image redis:3.0.7 redis
更新策略可以通过docker service inspect redis --pretty查看
...
UpdateConfig:
Parallelism: 1
Delay: 10s
On failure: pause
Monitoring Period: 5s
Max failure ratio: 0
Update order: stop-first
...
创建、更新、回滚
# docker service create --name my_web \
--replicas 6 \
--update-delay 10s \
--update-parallelism 2 \
--update-failure-action rollback \
--rollback-parallelism 2 \
--rollback-monitor 20s \
nginx:1.12
# docker service ps my_web
更新，可以看到是并发2个执行更新的
root@node-40:~# docker service update --image nginx:1.13 my_web
root@node-40:~# docker service ps my_web
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
q6j1s65l116c my_web.1 nginx:1.13 node-60 Running Preparing 10 seconds ago
kl5ae4w5boh1 \_ my_web.1 nginx:1.12 node-50 Shutdown Shutdown 8 seconds ago
vneuky0ivupt my_web.2 nginx:1.13 node-50 Running Preparing 10 seconds ago
f6170j8f7wph \_ my_web.2 nginx:1.12 node-60 Shutdown Shutdown 8 seconds ago
saih08dad4x5 my_web.3 nginx:1.12 node-50 Running Running 2 minutes ago
o0ted8mul45m my_web.4 nginx:1.12 node-60 Running Running 3 minutes ago
sj8vqi0bjfep my_web.5 nginx:1.12 node-50 Running Running 2 minutes ago
se16vb2lhgv7 my_web.6 nginx:1.12 node-60 Running Running 3 minutes ago
测试更新到busybox，由于busybox启动后不会常驻前台，所以理论上会启动失败，看Swarm是否能够执行回滚
root@node-40:~# docker service update --image busybox my_web
root@node-40:~# docker service ps my_web
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
ys01or2wc01u my_web.1 nginx:1.12 node-60 Running Running about a minute ago
yyb0x879wslq my_web.2 nginx:1.12 node-60 Running Running 8 seconds ago
f846l2w197yi \_ my_web.2 busybox:latest node-60 Shutdown Complete 14 seconds ago
odyjcfw2rfi9 \_ my_web.2 busybox:latest node-60 Shutdown Complete 21 seconds ago
kbxszo8dxhzc \_ my_web.2 nginx:1.12 node-50 Shutdown Shutdown 23 seconds ago
ymqtmrnte4vg my_web.3 nginx:1.12 node-50 Running Running 14 seconds ago
...
root@node-40:~# docker service ls -f "name=my_web"
ID NAME MODE REPLICAS IMAGE PORTS
n2g46nc5iaoy my_web replicated 6/6 nginx:1.12
可以看到最终还是回滚了，没有运行busybox~
在试下手动回滚，首先更新my_web
root@node-40:~# docker service update --image nginx:1.13 my_web
dockmy_web
Since --detach=false was not specified, tasks will be updated in the background.
In a future release, --detach=false will become the default.
root@node-40:~# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
3n0ixuvnbgcg redis replicated 2/2 redis:3.0.7
iwnj041mw0xn hello replicated 2/2 busybox:latest
n2g46nc5iaoy my_web replicated 6/6 nginx:1.13
n7e2zj2f8i9r lotus replicated 3/3 busybox:latest
然后尝试回滚，可以看到手动回滚OK了，而且并发2个进行回滚
root@node-40:~# docker service update --rollback my_web
my_web
Since --detach=false was not specified, tasks will be updated in the background.
In a future release, --detach=false will become the default.
root@node-40:~# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
3n0ixuvnbgcg redis replicated 2/2 redis:3.0.7
iwnj041mw0xn hello replicated 2/2 busybox:latest
n2g46nc5iaoy my_web replicated 4/6 nginx:1.12
n7e2zj2f8i9r lotus replicated 3/3 busybox:latest
查看服务日志
root@node-40:~# docker service logs my_web
删除服务
root@node-40:~# docker service rm my_web