执行命令docker service ps tomcat查看服务，可以看到新版本容器逐个启动的过程：
[root@m0 ~]# docker service ps tomcat
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
w32tjahze2fk tomcat.1 tomcat:7.0.96-jdk8-openjdk m2 Running Running 56 minutes ago
yj5czwwhrrsh tomcat.2 tomcat:7.0.96-jdk8-openjdk m0 Running Running 56 minutes ago
semuna9awsn7 tomcat.3 tomcat:9.0.24-jdk11-openjdk w1 Running Running 15 seconds ago
pq40995nbd0k \_ tomcat.3 tomcat:7.0.96-jdk8-openjdk w1 Shutdown Shutdown about a minute ago
y1y6z1jczel1 tomcat.4 tomcat:7.0.96-jdk8-openjdk m1 Running Running 15 minutes ago
oot3yex74v4t tomcat.5 tomcat:9.0.24-jdk11-openjdk w0 Running Preparing 5 seconds ago
w0dcii8f79os \_ tomcat.5 tomcat:7.0.96-jdk8-openjdk w0 Shutdown Shutdown 3 seconds ago
升级完成后，用浏览器访问服务，可见tomcat版本已经升级：
删除服务
执行命令docker service rm tomcat即可删除服务：
[root@m0 ~]# docker service rm tomcat
tomcat
[root@m0 ~]# docker service ls
ID NAME MODE REPLICAS IMAGE
至此，Docker Swarm从部署到基本操都已经体验过一次了，希望您在搭建环境的时候，本文能给您一些参考。