Docker swarm 是docker官方的三大项目之一，提供docker容器集群服务，是docker官方对容器云生态支持的核心方案，Docker Swarm项目开始于2014年，是Docker公司推出的第一个容器集群项目。使用docker swarm可以将多个docker主机封装为一个大型的虚拟docker主机，swarm集群提供给用户管理集群内所有容器的操作接口与使用一台docker主机几乎相同，从而可以快速打造一套容器云服务
Docker Swarmkit项目开始于2016年，是Docker公司推出的第二个容器集群项目，于Docker1.12版本正式发布。虽然也叫Swarm，但是与第一个项目完全不同。该项目直接在Docker Engine上内嵌了集群管理功能，并新增了集群管理的用户接口。
两个容器集群项目可能实现了相同的功能，但其上层接口还是有很大的不同，Docker公司推荐用户使用更适合自己的项目，如果都没有使用过，推荐使用后者。另外，Docker Swarm项目并没有被Docker公司列为不推荐的项目，仍然会继续支持新的Docker Engine的功能。
swarm v1是典型的mater-slave结构，需要通过发现服务来选举出manager，而manager是中心管理节点，而各个节点通过运行agent接受manager的统一管理
swarm v2中，swarm集群会自动通过Raft协议分布式选举出manager节点，因此无需配置额外的发现服务，从而避免了单点瓶颈；且swarm v2内置了DNS负载均衡和对外部负载均衡机制的支持
本实验基于docker swarm v1版本，实验环境如下：
docker-1 192.168.1.193
docker-2 192.168.1.194
docker-3 192.168.1.195
在各个docker主机上安装swarm，启动docker daemon
root@docker-1:~# docker pull swarm
root@docker-1:~# docker run --rm swarm -v
swarm version 1.2.8 (48d86b1)
root@docker-1:~# service docker stop
docker stop/waiting
root@docker-1:~# dockerd -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock
root@docker-1:~# netstat -tunlp|grep docker
tcp6 0 0 :::2375 :::* LISTEN 1698/dockerd
root@docker-2:~# docker pull swarm
root@docker-2:~# service docker stop
docker stop/waiting
root@docker-2:~# dockerd -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock
root@docker-3:~# docker pull swarm
root@docker-3:~# service docker stop
docker stop/waiting
root@docker-3:~# dockerd -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock
在任意一个节点上使用docker swarm 命令来在docker hub上进行注册（采用docker hub的服务发现后端，但必须要求所有docker主机可以访问外网），且会产生一个token，用来标识和管理集群
root@docker-1:~# docker run --rm swarm create
1081dc3745b8dfd45ff863c13d74d96c
在所有要加入swarm集群的docker主机上执行swarm join命令，将各个节点加入swarm集群
root@docker-1:~# docker run -d swarm join --addr=192.168.1.193:2375 token://1081dc3745b8dfd45ff863c13d74d96c
fbc0c47268e1e631c4839b41107cac08bd33c9b27380283768efda84ab3ae373
root@docker-2:~# docker run -d swarm join --addr=192.168.1.194:2375 token://1081dc3745b8dfd45ff863c13d74d96c
b88ab2e5eb4e787ad56df06fd6f7e879aacbd35b36743d2943002b882cd8865f
root@docker-3:~# docker run -d swarm join --addr=192.168.1.195:2375 token://1081dc3745b8dfd45ff863c13d74d96c
1b62af7b1ecf7d428f7dd25df71a0523742cecdb1341eb76560225a77336b12f
因为没有配置manager节点，所以此命令无法使用
root@docker-1:~# docker node ls
Error response from daemon: This node is not a swarm manager. Use "docker swarm init" or "docker swarm join" to connect this node to swarm and try again.
查看各个节点的容器情况，可以与后续实验做对比
root@docker-1:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
fbc0c47268e1 swarm "/swarm join --add..." 6 minutes ago Up 6 minutes 2375/tcp competent_benz
root@docker-1:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
fbc0c47268e1 swarm "/swarm join --add..." 6 minutes ago Up 6 minutes 2375/tcp competent_benz
root@docker-2:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b88ab2e5eb4e swarm "/swarm join --add..." 4 minutes ago Up 4 minutes 2375/tcp romantic_poincare
root@docker-2:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b88ab2e5eb4e swarm "/swarm join --add..." 4 minutes ago Up 4 minutes 2375/tcp romantic_poincare
root@docker-3:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b88ab2e5eb4e swarm "/swarm join --add..." 4 minutes ago Up 4 minutes 2375/tcp romantic_poincare
root@docker-3:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
b88ab2e5eb4e swarm "/swarm join --add..." 4 minutes ago Up 4 minutes 2375/tcp romantic_poincare
用swarm manage命令将docker-1节点配置成为管理节点该命令将启用manager服务,且默认监听到2375端口，所有集群的管理都可以通过该服务的接口进行操作，但是manager服务和docker服务
的监听端口相同，而这样做是为了兼容其他基于docker的服务，可以无缝的切换到swarm平台；但有与本次实验采用的是docker容器的方式启用manager服务，本地的2375端口已被docker daemon占用，
所以将manager服务的端口映射到一个空闲的端口12375
root@docker-1:~# docker run -d -p 12375:2375 swarm manage token://1081dc3745b8dfd45ff863c13d74d96c
ad81e842302de642ba7bf5514b12ce6ea46070abc68c6e15a4eefc0b8e5dfc57
root@docker-1:~# netstat -tunlp |grep docker
tcp6 0 0 :::12375 :::* LISTEN 2191/docker-proxy
tcp6 0 0 :::2375 :::* LISTEN 1698/dockerd
产看docker-1节点运行的容器和所有容器
root@docker-1:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ad81e842302d swarm "/swarm manage tok..." 4 seconds ago Up 3 seconds 0.0.0.0:12375->2375/tcp hungry_benz
fbc0c47268e1 swarm "/swarm join --add..." 19 minutes ago Up 19 minutes 2375/tcp competent_benz
root@docker-1:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
ad81e842302d swarm "/swarm manage tok..." 13 seconds ago Up 12 seconds 0.0.0.0:12375->2375/tcp hungry_benz
fbc0c47268e1 swarm "/swarm join --add..." 19 minutes ago Up 19 minutes 2375/tcp competent_benz
可以再任意节点执行swarm list 命令查看集群的节点列表
root@docker-1:~# docker run --rm swarm list token://1081dc3745b8dfd45ff863c13d74d96c
192.168.1.193:2375
192.168.1.195:2375
192.168.1.194:2375
root@docker-2:~# docker run --rm swarm list token://1081dc3745b8dfd45ff863c13d74d96c
192.168.1.193:2375
192.168.1.195:2375
192.168.1.194:2375
可以再任意节点可以创建集群容器，如docker-3
root@docker-3:~# docker -H 192.168.1.193:12375 run -d centos ping www.baidu.com
41ca94b3da41767ecd87de7d37a3611141dc8b36aad52211b75374b153628312
查看集群所有节点运行的容器
root@docker-3:~# docker -H 192.168.1.193:12375 ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
41ca94b3da41 centos "ping www.baidu.com" 3 minutes ago Up 3 minutes docker-2/vigilant_bose
查看集群所有节点的容器
root@docker-3:~# docker -H 192.168.1.193:12375 ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
41ca94b3da41 centos "ping www.baidu.com" 3 minutes ago Up 3 minutes docker-2/vigilant_bose
ad81e842302d swarm "/swarm manage tok..." 13 minutes ago Up 13 minutes 192.168.1.193:12375->2375/tcp docker-1/hungry_benz
1b62af7b1ecf swarm "/swarm join --add..." 30 minutes ago Up 30 minutes 2375/tcp docker-3/ecstatic_elion
b88ab2e5eb4e swarm "/swarm join --add..." 30 minutes ago Up 30 minutes 2375/tcp docker-2/romantic_poincare
fbc0c47268e1 swarm "/swarm join --add..." 32 minutes ago Up 32 minutes 2375/tcp docker-1/competent_benz
查看本节点docker-3 正在运行的容器
root@docker-3:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1b62af7b1ecf swarm "/swarm join --add..." 31 minutes ago Up 31 minutes 2375/tcp ecstatic_elion
查看本节点docker-3 的所有容器
root@docker-3:~# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1b62af7b1ecf swarm "/swarm join --add..." 31 minutes ago Up 31 minutes 2375/tcp ecstatic_elion
root@docker-3:~#
在docker-1主机上分别执行节点和集群的docker info看看，可以对比一下
root@docker-1:~# docker info
Containers: 2
Running: 2
Paused: 0
Stopped: 0
Images: 1
Server Version: 17.05.0-ce
Storage Driver: aufs
Root Dir: /var/lib/docker/aufs
Backing Filesystem: extfs
Dirs: 7
Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
Volume: local
Network: bridge host macvlan null overlay
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 9048e5e50717ea4497b757314bad98ea3763c145
runc version: 9c2d8d184e5da67c95d601382adf14862e4f2228
init version: 949e6fa
Security Options:
apparmor
Kernel Version: 4.4.0-31-generic
Operating System: Ubuntu 14.04.5 LTS
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 726.7MiB
Name: docker-1
ID: A3OC:Z223:S7IY:6KF6:U2TE:N26E:CEMT:2VEH:5AR6:LVY5:U2KI:52P5
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Experimental: false
Insecure Registries:
127.0.0.0/8
Live Restore Enabled: false
WARNING: No swap limit support
root@docker-1:~# docker -H 192.168.1.193:12375 info
Containers: 5
Running: 5
Paused: 0
Stopped: 0
Images: 5
Server Version: swarm/1.2.8
Role: primary
Strategy: spread
Filters: health, port, containerslots, dependency, affinity, constraint, whitelist
Nodes: 3
docker-1: 192.168.1.193:2375
└ ID: A3OC:Z223:S7IY:6KF6:U2TE:N26E:CEMT:2VEH:5AR6:LVY5:U2KI:52P5|192.168.1.193:2375
└ Status: Healthy
└ Containers: 2 (2 Running, 0 Paused, 0 Stopped)
└ Reserved CPUs: 0 / 1
└ Reserved Memory: 0 B / 763 MiB
└ Labels: kernelversion=4.4.0-31-generic, operatingsystem=Ubuntu 14.04.5 LTS, ostype=linux, storagedriver=aufs
└ UpdatedAt: 2017-10-15T13:18:50Z
└ ServerVersion: 17.05.0-ce
docker-2: 192.168.1.194:2375
└ ID: LTSZ:NUCW:U7PJ:E2MB:UD4K:QNS4:EOYG:YC5B:XEYU:BNM5:MZGE:X4R4|192.168.1.194:2375
└ Status: Healthy
└ Containers: 2 (2 Running, 0 Paused, 0 Stopped)
└ Reserved CPUs: 0 / 1
└ Reserved Memory: 0 B / 776.6 MiB
└ Labels: kernelversion=4.4.0-31-generic, operatingsystem=Ubuntu 14.04.5 LTS, ostype=linux, storagedriver=aufs
└ UpdatedAt: 2017-10-15T13:19:04Z
└ ServerVersion: 17.05.0-ce
docker-3: 192.168.1.195:2375
└ ID: A42N:WYIC:KJRG:SPED:IJIS:IYQP:23T4:EWDP:6CT7:IFMB:ZIDF:37WN|192.168.1.195:2375
└ Status: Healthy
└ Containers: 1 (1 Running, 0 Paused, 0 Stopped)
└ Reserved CPUs: 0 / 1
└ Reserved Memory: 0 B / 513.1 MiB
└ Labels: kernelversion=4.4.0-31-generic, operatingsystem=Ubuntu 14.04.5 LTS, ostype=linux, storagedriver=aufs
└ UpdatedAt: 2017-10-15T13:19:03Z
└ ServerVersion: 17.05.0-ce
Plugins:
Volume:
Network:
Swarm:
NodeID:
Is Manager: false
Node Address:
Kernel Version: 4.4.0-31-generic
Operating System: linux
Architecture: amd64
CPUs: 3
Total Memory: 2.005GiB
Name: ad81e842302d
Docker Root Dir:
Debug Mode (client): false
Debug Mode (server): false
Experimental: false
Live Restore Enabled: false
可以发现docker-1上运行有创建manager服务和swarm join时的两个容器，docker-2上运行有swarm join和 ping www.baidu.com
(这个容器是在docker-3上通过manager服务创建的，但却运行在docker-2上，可见是swarm集群调度策略分配的）的两个容器，docker-3上只有swarm join
创建一个nginx服务
root@docker-1:~# docker -H 192.168.1.193:12375 run -d --name my-web --publish 8080:80 nginx
2a888979b129767ff73562587e5cf6672aac13c47d69ea4673887d87f6be552a
通过下面命令可以看到nginx运行在docker-3上（swarm调度策略分配的）
root@docker-1:~# docker -H 192.168.1.193:12375 ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
2a888979b129 nginx "nginx -g 'daemon ..." 15 seconds ago Up 14 seconds 192.168.1.195:8080->80/tcp docker-3/my-web
41ca94b3da41 centos "ping www.baidu.com" 2 hours ago Up 2 hours docker-2/vigilant_bose
root@docker-3:~# netstat -tunlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 910/sshd
tcp6 0 0 :::22 :::* LISTEN 910/sshd
tcp6 0 0 :::2375 :::* LISTEN 1549/dockerd
tcp6 0 0 :::8080 :::* LISTEN 3761/docker-proxy
root@docker-1:~# curl http://192.168.1.195:8080
Welcome to nginx!
If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.
For online documentation and support please refer to
Commercial support is available at
Thank you for using nginx.
进入nginx容器进行服务修改
root@docker-1:~# docker -H 192.168.1.193:12375 exec -it 2a888979b129 /bin/bash
root@2a888979b129:/# apt-get update &&apt-get install -y vim net-tools
root@2a888979b129:/# netstat -tunlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 1/nginx: master pro
修改nginx服务的配置文件
root@2a888979b129:/# vim /etc/nginx/conf.d/default.conf
location / {
root /var/www/html/;
index index.html index.htm;
}
root@2a888979b129:/# mkdir /var/www/html/ -p
root@2a888979b129:/# vim /var/www/html/index.html
Hello,Docker ^_^
root@2a888979b129:/# service nginx restart
[....] Restarting nginx: nginx
重启nginx后，nginx容器会终止，需要重新启动
root@docker-1:~# docker -H 192.168.1.193:12375 start 2a888979b129
2a888979b129
修改后，访问成功
root@docker-2:~# curl http://192.168.1.195:8080
Hello,Docker ^_^
