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上一篇文章对Swarm进行了介绍以及Swarm集群的搭建，本文将介绍在Swarm集群中如何对服务进行管理以及数据卷挂载。
上期回顾： Docker Swarm（一）：Swarm介绍与集群搭建
服务管理
创建服务
Swarm特点：弹性、扩缩容
之前操作的 docker run 、docker-compose up 启动一个一项目，都是单机的；现在使用swarm集群，通过 docker service 来管理
之前单机：一个service就是指向的一个容器，比如一个 nginx服务指向一个nginx容器；
现在集群 ：一个service可能指向一个或多个容器，比如对外暴露了一个nginx服务，实际上后端有多个nginx容器构成（就像负载均衡）。
命令：
[root@docker-1 ~]# docker service --help
Usage: docker service COMMAND
Manage services
Commands:
create Create a new service # 创建一个服务
inspect Display detailed information on one or more services # 查看服务详细信息
logs Fetch the logs of a service or task # 查看日志
ls List services
ps List the tasks of one or more services
rm Remove one or more services # 移除服务
rollback Revert changes to a service's configuration
scale Scale one or multiple replicated services # 伸缩一个或多个副本
update Update a service # 更新服务
Run 'docker service COMMAND --help' for more information on a command.
创建服务：
[root@docker-1 ~]# docker service create -p 8888:80 --name my-nginx nginx
pvom9t9zbdkh3uk42jj3q06np
overall progress: 1 out of 1 tasks
1/1: running [==================================================>]
verify: Service converged查看服务：
# 通过 docker service ls 可以看到有哪些service在集群上
# 当前只有一个 my-nginx service，当前只有1个副本，总共1个副本
[root@docker-1 ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
pvom9t9zbdkh my-nginx replicated 1/1 nginx:latest *:8888->80/tcp
# 通过 docker service ps my-nginx 可以查看执行的service部署情况
# 当前运行在 docker-3 机器上
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
rdz0t33xdvxx my-nginx.1 nginx:latest docker-3 Running Running 5 minutes ago当前my-nginx服务中，真正nginx容器运行在docker-3上，docker-1虽然是manager节点，但也能跑服务。
访问测试：
尽管真正的nginx容器运行在docker-3上，但是由于是采用集群部署模式，此时无论使用集群中的哪个主机IP访问8888端口都能够访问到nginx服务。
http://192.168.92.130:8888/
http://192.168.92.152:8888/
http://192.168.92.153:8888/
http://192.168.92.154:8888/
扩缩容
两个方式：
- docker service update
- docker service scale
通过 docker service update 扩缩容
当前my-nginx只有1个副本，现在给它扩到3个，使用 docker service update --replicas 3 my-nginx
[root@docker-1 ~]# docker service update --replicas 3 my-nginx
my-nginx
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
[root@docker-1 ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
pvom9t9zbdkh my-nginx replicated 3/3 nginx:latest *:8888->80/tcp
# 3个nginx副本分别在 docker-1、docker-3、docker-4机器上各自启动了一个容器
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
rdz0t33xdvxx my-nginx.1 nginx:latest docker-3 Running Running 17 minutes ago
m2h63c6g4aee my-nginx.2 nginx:latest docker-1 Running Running 48 seconds ago
v0t9kqfplu9f my-nginx.3 nginx:latest docker-4 Running Running 42 seconds ago访问测试：
尽管docker-2上没有部署nginx容器，但是由于是采用集群部署模式，此时无论使用集群中的哪个主机IP访问8888端口都能够访问到nginx服务，包括docker-2。
http://192.168.92.130:8888/
http://192.168.92.152:8888/
http://192.168.92.153:8888/
http://192.168.92.154:8888/
扩到10个：
[root@docker-1 ~]# docker service update --replicas 10 my-nginx
my-nginx
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@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
rdz0t33xdvxx my-nginx.1 nginx:latest docker-3 Running Running 22 minutes ago
m2h63c6g4aee my-nginx.2 nginx:latest docker-1 Running Running 5 minutes ago
v0t9kqfplu9f my-nginx.3 nginx:latest docker-4 Running Running 4 minutes ago
tcfx6gcwcmwe my-nginx.4 nginx:latest docker-4 Running Running 39 seconds ago
pmi5gdg62wsg my-nginx.5 nginx:latest docker-1 Running Running 39 seconds ago
jvu3wmhpv7q2 my-nginx.6 nginx:latest docker-2 Running Running 19 seconds ago
nycvkr4ffnah my-nginx.7 nginx:latest docker-3 Running Running 38 seconds ago
fr6nmwmkel41 my-nginx.8 nginx:latest docker-2 Running Running 19 seconds ago
u78vj5easfq0 my-nginx.9 nginx:latest docker-2 Running Running 19 seconds ago
ck5p63zoqsq6 my-nginx.10 nginx:latest docker-3 Running Running 38 seconds ago减到1个：
[root@docker-1 ~]# docker service update --replicas 1 my-nginx
my-nginx
overall progress: 1 out of 1 tasks
1/1: running [==================================================>]
verify: Service converged
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
rdz0t33xdvxx my-nginx.1 nginx:latest docker-3 Running Running 22 minutes ago通过 docker service scale 扩缩容
[root@docker-1 ~]# docker service scale my-nginx=4
my-nginx scaled to 4
overall progress: 4 out of 4 tasks
1/4: running [==================================================>]
2/4: running [==================================================>]
3/4: running [==================================================>]
4/4: running [==================================================>]
verify: Service converged
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
rdz0t33xdvxx my-nginx.1 nginx:latest docker-3 Running Running 24 minutes ago
kbzanlwvfffq my-nginx.2 nginx:latest docker-4 Running Running 19 seconds ago
y1bkw76cnsxh my-nginx.3 nginx:latest docker-2 Running Running 19 seconds ago
jqtazzjq715c my-nginx.4 nginx:latest docker-1 Running Running 19 seconds ago综上：使用swarm扩缩容真的是轻轻松松。
故障转移
当前在每台主机上都运行着一个nginx容器，我们停止docker-4上的nginx容器，模拟容器出现故障。
[root@docker-4 ~]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
99c0465704ba nginx:latest "/docker-entrypoint.…" 3 minutes ago Up 3 minutes 80/tcp my-nginx.2.kbzanlwvfffqm4eu2nr9m390u
[root@docker-4 ~]# docker stop 99c0465704ba
99c0465704ba再来看看service运行情况：
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
rdz0t33xdvxx my-nginx.1 nginx:latest docker-3 Running Running 27 minutes ago
0l0h4vh4tw79 my-nginx.2 nginx:latest docker-4 Running Running 8 seconds ago
kbzanlwvfffq \_ my-nginx.2 nginx:latest docker-4 Shutdown Complete 14 seconds ago
y1bkw76cnsxh my-nginx.3 nginx:latest docker-2 Running Running 3 minutes ago
jqtazzjq715c my-nginx.4 nginx:latest docker-1 Running Running 3 minutes ago可以看到docker-4上的nginx容器已经 Shutdown了，自动在docker-4上重建了一个新的nginx容器。
再次停止docker-4上重建的nginx容器，再次查看service运行情况，依然是在docker-4上重建的：
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
rdz0t33xdvxx my-nginx.1 nginx:latest docker-3 Running Running 30 minutes ago
5121f134n75t my-nginx.2 nginx:latest docker-4 Running Running 49 seconds ago
0l0h4vh4tw79 \_ my-nginx.2 nginx:latest docker-4 Shutdown Complete 55 seconds ago
kbzanlwvfffq \_ my-nginx.2 nginx:latest docker-4 Shutdown Complete 3 minutes ago
y1bkw76cnsxh my-nginx.3 nginx:latest docker-2 Running Running 6 minutes ago
jqtazzjq715c my-nginx.4 nginx:latest docker-1 Running Running 6 minutes ago是不是停止哪个机器上的容器就在哪个机器上重建呢？
直接将docker-4主机关机，再查看：
此时docker-4上的nginx容器，自动转移到了docker-3主机上，并不受主机的影响，会在集群中自动调度。
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
rdz0t33xdvxx my-nginx.1 nginx:latest docker-3 Running Running 31 minutes ago
rsfjw6pck39l my-nginx.2 nginx:latest docker-3 Running Starting less than a second ago
5121f134n75t \_ my-nginx.2 nginx:latest docker-4 Shutdown Running 2 minutes ago
0l0h4vh4tw79 \_ my-nginx.2 nginx:latest docker-4 Shutdown Complete 2 minutes ago
kbzanlwvfffq \_ my-nginx.2 nginx:latest docker-4 Shutdown Complete 4 minutes ago
y1bkw76cnsxh my-nginx.3 nginx:latest docker-2 Running Running 7 minutes ago
jqtazzjq715c my-nginx.4 nginx:latest docker-1 Running Running 7 minutes ago删除服务
使用 docker service rm
[root@docker-1 ~]# docker service rm my-nginx
my-nginx
[root@docker-1 ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS镜像变更/升级
重新新建service来测试：
docker service create -p 8888:80 --name my-nginx nginx# 将镜像变更为 nginx:1.20
[root@docker-1 ~]# docker service update --image nginx:1.20 my-nginx
my-nginx
overall progress: 1 out of 1 tasks
1/1: running [==================================================>]
verify: Service converged# 老镜像nginx:latest停止，新镜像nginx:1.20启用
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
z2gmcjtljhqg my-nginx.1 nginx:1.20 docker-3 Running Running about a minute ago
svh5jpysqcc3 \_ my-nginx.1 nginx:latest docker-3 Shutdown Shutdown about a minute ago回滚到上个版本
# 回滚到上个版本
[root@docker-1 ~]# docker service update --rollback my-nginx
my-nginx
rollback: manually requested rollback
overall progress: rolling back update: 1 out of 1 tasks
1/1: running [> ]
verify: Service converged
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
xak0904ma7wf my-nginx.1 nginx:latest docker-1 Running Running 12 seconds ago
z2gmcjtljhqg \_ my-nginx.1 nginx:1.20 docker-3 Shutdown Shutdown 13 seconds ago
svh5jpysqcc3 \_ my-nginx.1 nginx:latest docker-3 Shutdown Shutdown 6 minutes ago删除service：
[root@docker-1 ~]# docker service rm my-nginx
my-nginx更多使用用法请看：
docker service update --help
数据卷挂载
我们之前已经学习过在容器中使用volume数据卷，这里我们来看看如何在swarm集群中使用数据卷。
volume数据卷
创建一个新的数据卷：
[root@docker-1 ~]# docker volume create my-volume
my-volume
[root@docker-1 ~]# docker volume ls
DRIVER VOLUME NAME
local my-volume
[root@docker-1 ~]# docker volume inspect my-volume
[
{
"CreatedAt": "2022-03-10T16:45:01+08:00",
"Driver": "local",
"Labels": {},
"Mountpoint": "/var/lib/docker/volumes/my-volume/_data",
"Name": "my-volume",
"Options": {},
"Scope": "local"
}
]创建一个service并使用数据库挂载：
# 创建service并使用volume挂载
# src可写为source，dst可写为target
[root@docker-1 ~]# docker service create --replicas 3 --mount type=volume,src=my-volume,dst=/vol_test --name my-nginx nginx
frar0fbts1f3ezwyttweoa10r
overall progress: 3 out of 3 tasks
1/3: running [==================================================>]
2/3: running [==================================================>]
3/3: running [==================================================>]
verify: Service converged
[root@docker-1 ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
frar0fbts1f3 my-nginx replicated 3/3 nginx:latest
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
jbz6e1w0ce7n my-nginx.1 nginx:latest docker-1 Running Running 18 seconds ago
q4fuyxb7ctph my-nginx.2 nginx:latest docker-3 Running Running 17 seconds ago
f3ce25vrbrpb my-nginx.3 nginx:latest docker-2 Running Running 18 seconds ago在3个主机上部署了nginx容器，查看有没有挂载成功，我们逐个登录主机进入容器查看：
首先看docker-1机器：
[root@docker-1 ~]# docker exec -it 7865bec81dce /bin/bash
root@7865bec81dce:/# ls /vol_test/
root@7865bec81dce:/# echo "This is volume test from docker-1" > /vol_test/docker-1.txt
root@7865bec81dce:/# ls /vol_test/
docker-1.txt
root@7865bec81dce:/# exit
exit
[root@docker-1 ~]# ls /var/lib/docker/volumes/my-volume/_data/
docker-1.txt
[root@docker-1 ~]# cat /var/lib/docker/volumes/my-volume/_data/docker-1.txt
This is volume test from docker-1再来看 docker-2、docker-3 发现，我们在docker-1容器里创建的文件，docker-2、docker-3的容器里并没有，说明通过此方式挂载的数据卷只能用于本地，是不能够共享的。
另一种挂载方式：
语法：
docker service create --mount type=bind,source=/host_dir,target=/container_dir
# source路径要求在部署的目标机器上真实存在，比如部署3个副本有可能分部在不同主机，那每个主机上都必须要存在此目录示例：
[root@docker-1 ~]# docker service create --mount type=bind,source=/opt/web,target=/usr/share/nginx/html -p 8888:80 --name my-nginx nginx
mumiyabkxyceeymzmkeoz637q
overall progress: 1 out of 1 tasks
1/1: running [==================================================>]
verify: Service converged
[root@docker-1 ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
mumiyabkxyce my-nginx replicated 1/1 nginx:latest *:8888->80/tcp
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
jwmr1e9zn1uk my-nginx.1 nginx:latest docker-3 Running Running 33 seconds ago部署到了docker-3.
在docker-3机器上 /opt/web/目录下创建一个index.html 文件：
[root@docker-3 ~]# echo "This is test from docker-3" > /opt/web/index.html
[root@docker-3 ~]# ls /opt/web/
index.html访问测试：
使用任意主机IP访问8888端口：
[root@docker-1 ~]# curl http://192.168.92.153:8888
This is test from docker-3删除service：
[root@docker-1 ~]# docker service rm my-nginx
my-nginx小总结：
通过以上对数据卷的操作案例可以看出，数据卷之间的数据是不能够在集群中共享的，对于集群部署意义并不大，如果能共享数据才是极好的，可以使用nfs解决。
通过nfs在集群中共享数据：
我们需要用一台服务器当作nfs服务器，这里我们把docker-4当作nfs服务器，在docker-4上安装nfs服务。
yum install nfs-utils -y
mkdir -p /data/nfs
# 编辑 /etc/exports 文件，内容如下
[root@docker-4 ~]# cat /etc/exports
/data/nfs 192.168.92.0/24(rw,no_root_squash)
# 启动nfs
systemctl start nfs
systemctl enable nfs创建服务：
[root@docker-1 ~]# docker service create --mount 'type=volume,source=nfsvolume,target=/usr/share/nginx/html,volume-driver=local,volume-opt=type=nfs,volume-opt=device=:/data/nfs,"volume-opt=o=addr=192.168.92.154,rw,nfsvers=4,async"' --replicas 4 -p 8888:80 --name my-nginx nginx
vqxjrbz91rdy9yutgnfmt2icc
overall progress: 4 out of 4 tasks
1/4: running [==================================================>]
2/4: running [==================================================>]
3/4: running [==================================================>]
4/4: running [==================================================>]
verify: Service converged
[root@docker-1 ~]#
[root@docker-1 ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
vqxjrbz91rdy my-nginx replicated 4/4 nginx:latest *:8888->80/tcp
[root@docker-1 ~]#
[root@docker-1 ~]# docker service ps my-nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
yuwkqgd3mlyb my-nginx.1 nginx:latest docker-3 Running Running 15 seconds ago
h6n3t2v9c04x my-nginx.2 nginx:latest docker-2 Running Running 16 seconds ago
igoqir801uhu my-nginx.3 nginx:latest docker-4 Running Running 16 seconds ago
3jibweokor60 my-nginx.4 nginx:latest docker-1 Running Running 16 seconds ago查看volume：
[root@docker-1 ~]# docker volume ls
DRIVER VOLUME NAME
local nfsvolume
[root@docker-1 ~]#
[root@docker-1 ~]# docker volume inspect nfsvolume
[
{
"CreatedAt": "2022-03-10T17:44:05+08:00",
"Driver": "local",
"Labels": {},
"Mountpoint": "/var/lib/docker/volumes/nfsvolume/_data",
"Name": "nfsvolume",
"Options": {
"device": ":/data/nfs",
"o": "addr=192.168.92.154,rw,nfsvers=4,async",
"type": "nfs"
},
"Scope": "local"
}
]每个机器上都自动创建了 nfsvolume 数据卷。
访问测试：
在 docker-4 上向/data/nfs/目录下创建一个index.html文件
[root@docker-4 ~]# echo "This is nfs volume test from docker-4" > /data/nfs/index.html访问：
[root@docker-1 ~]# curl http://192.168.92.130:8888
This is nfs volume test from docker-4成功访问到，成功。
多服务Swarm集群部署
前面我们操作的都是单个服务在swarm集群中部署，那如果要一次部署多个服务呢？
实际上我们可以利用compose来实现，compose默认只是针对多个服务在单机上批量部署的，但我们可以利用到compose中的deploy来定义在集群中如何部署。
关于deploy的官方文档: https://docs.docker.com/compose/compose-file/compose-file-v3/#deploy
deploy 部分的配置只在使用 docker stack deploy 部署到swarm集群中有效，使用 docker-compose 和 docker-compose run 时，deploy部分的配置将会忽略不会被执行。
如下 compose.yml
version: "3.9"
services:
redis:
image: redis:alpine
deploy:
replicas: 6
placement:
max_replicas_per_node: 1
update_config:
parallelism: 2
delay: 10s
restart_policy:
condition: on-failure启动部署并查看：
# 启动部署
[root@docker-1 ~]# docker stack deploy -c compose.yml up
Creating network up_default
Creating service up_redis
# 看到共计6个副本，成功了4个，因为 (max 1 per node) 每一个节点最多只运行1个副本，这里我们只有4个节点，所以只有4个副本运行成功
[root@docker-1 ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
p0pn2w313tob up_redis replicated 4/6 (max 1 per node) redis:alpine
# 每个node上只有一个副本在运行，因为compose.yml中定义了 max_replicas_per_node: 1 每一个节点最多只运行1个副本，这里我们只有4个节点，所以看到有两个失败
[root@docker-1 ~]# docker service ps up_redis
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
t9b1s57ckrqq up_redis.1 redis:alpine docker-2 Running Running about a minute ago
56oplb1h7n3e up_redis.2 redis:alpine docker-4 Running Running about a minute ago
layzi9ggfu4u up_redis.3 redis:alpine docker-3 Running Running about a minute ago
y67mnxyppjcb up_redis.4 redis:alpine Running Pending about a minute ago "no suitable node (max replica…"
56ouwyy0akwi up_redis.5 redis:alpine Running Pending about a minute ago "no suitable node (max replica…"
sa8qso0r9m50 up_redis.6 redis:alpine docker-1 Running Running about a minute ago猜你喜欢
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