learning docker steps(5) ----- docker stack 初次体验
参考：https://docs.docker.com/get-started/part5/
stack 技术栈。技术栈是一组相关的服务，它们共享依赖项并且可以一起进行编排和扩展。单个技术栈能够定义和协调整个应用的功能（虽然很复杂的应用程序可能需要使用多个技术栈）。
按我的理解就是docker的最终的目标是为了提供服务：比如我们访问网站，计算网站被请求访问次数也是需求，要实现需求的话，就需要提供相关的服务，用什么实现呢，就是docker stack来实现。
在今后的学习当中我们如何学习到k8s的话，可以把它理解成k8s的pod概念。
如下是实践操作，按照参考的yaml有点小问题，稍微修改了一下：
root@vmuser-virtual-machine:/home/vmuser/workdir/services# docker-machine ssh myvm1 “docker swarm init –advertise-addr 192.168.99.100:2377”
Swarm initialized: current node (qmsgq8wgya34mfxgd94jvt2hh) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join –token SWMTKN-1-0l4021umvvtfjk9meufz4gks5gc8qa5yu16leg367m9s3ca24e-cwuj8c047v6xvvbxho2flx6xw 192.168.99.100:2377
To add a manager to this swarm, run ‘docker swarm join-token manager’ and follow the instructions.
root@vmuser-virtual-machine:/home/vmuser/workdir/services# docker-machine ssh myvm2 “docker swarm join –token SWMTKN-1-0l4021umvvtfjk9meufz4gks5gc8qa5yu16leg367m9s3ca24e-cwuj8c047v6xvvbxho2flx6xw 192.168.99.100:2377”
This node joined a swarm as a worker.
root@vmuser-virtual-machine:/home/vmuser/workdir/services# docker-machine ssh myvm1
## .
## ## ## ==
## ## ## ## ## ===
/”””””””””””””””””\___/ ===
~~~ {~~ ~~~~ ~~~ ~~~~ ~~~ ~ / ===- ~~~
\______ o __/
\ \ __/
\____\_______/
_ _ ____ _ _
| |__ ___ ___ | |_|___ \ __| | ___ ___| | _____ _ __
| ‘_ \ / _ \ / _ \| __| __) / _` |/ _ \ / __| |/ / _ \ ‘__|
| |_) | (_) | (_) | |_ / __/ (_| | (_) | (__| < __/ |
|_.__/ \___/ \___/ \__|_____\__,_|\___/ \___|_|\_\___|_|
Boot2Docker version 18.06.1-ce, build HEAD : c7e5c3e – Wed Aug 22 16:27:42 UTC 2018
Docker version 18.06.1-ce, build e68fc7a
docker@myvm1:~$ docker stack deploy -c docker-compose.yml getstartedlab
services.visualizer.deploy.placement must be a mapping
docker@myvm1:~$ docker stack deploy -c docker-compose.yml getstartedlab
services.visualizer.deploy.placement must be a mapping
docker@myvm1:~$ exit
exit status 1
通过去掉 解决该问题：
deploy:
placement:
constraints:[node.role == manager]
root@vmuser-virtual-machine:/home/vmuser/workdir/services# docker-machine ssh myvm1
## .
## ## ## ==
## ## ## ## ## ===
/”””””””””””””””””\___/ ===
~~~ {~~ ~~~~ ~~~ ~~~~ ~~~ ~ / ===- ~~~
\______ o __/
\ \ __/
\____\_______/
_ _ ____ _ _
| |__ ___ ___ | |_|___ \ __| | ___ ___| | _____ _ __
| ‘_ \ / _ \ / _ \| __| __) / _` |/ _ \ / __| |/ / _ \ ‘__|
| |_) | (_) | (_) | |_ / __/ (_| | (_) | (__| < __/ |
|_.__/ \___/ \___/ \__|_____\__,_|\___/ \___|_|\_\___|_|
Boot2Docker version 18.06.1-ce, build HEAD : c7e5c3e – Wed Aug 22 16:27:42 UTC 2018
Docker version 18.06.1-ce, build e68fc7a
docker@myvm1:~$ docker stack deploy -c docker-compose.yml getstartedlab
Creating network getstartedlab_webnet
Creating service getstartedlab_web
Creating service getstartedlab_visualizer
docker@myvm1:~$ exit
root@vmuser-virtual-machine:/home/vmuser/workdir/services# docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS
myvm1 * virtualbox Running tcp://192.168.99.100:2376 v18.06.1-ce
myvm2 – virtualbox Running tcp://192.168.99.101:2376 v18.06.1-ce
在页面http://192.168.99.101:8080/
root@vmuser-virtual-machine:/home/vmuser/workdir/services# docker-machine ssh myvm1 “docker stack ps getstartedlab”
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
yhauhypkguok getstartedlab_visualizer.1 dockersamples/visualizer:stable myvm1 Running Running 6 minutes ago
lo65xbvsmyfb getstartedlab_web.1 pan19881018/get-start:part2 myvm1 Running Running 7 minutes ago
m7fompj28ptg getstartedlab_web.2 pan19881018/get-start:part2 myvm2 Running Running 7 minutes ago
y1i1bghzyhuc getstartedlab_web.3 pan19881018/get-start:part2 myvm2 Running Running 7 minutes ago
mej5094xv5k6 getstartedlab_web.4 pan19881018/get-start:part2 myvm1 Running Running 7 minutes ago
z55f2hdwwyzc getstartedlab_web.5 pan19881018/get-start:part2 myvm2 Running Running 7 minutes ago
如下图所示：我们就把stack的样例实现了：
