服务发现
Swarm 需要使用到服务发现机制，发现服务是 Swarm 中极其关键的一环，Swarm 依赖它对集群中的其它节点进行感知和交互，集群的高可用也依赖于它完成，如果服务发现工作不正常，集群将无法操作
Swarm 目前支持四种服务发现工具：
- Hosted (用于测试，不要使用到生产)
- Consul
- etcd
- Zookeeper
下面选择 Consul 作为服务发现工具
代码语言：javascript复制[root@h104 ~]# docker run -d -p 8500:8500 --name=consul progrium/consul -server -bootstrap
Unable to find image 'progrium/consul:latest' locally
latest: Pulling from progrium/consul
3b4d28ce80e4: Pull complete
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d9125e9e799b: Verifying Checksum
Pulling repository docker.io/progrium/consul
e66fb6787628: Download complete
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Status: Downloaded newer image for progrium/consul:latest
docker.io/progrium/consul: this image was pulled from a legacy registry. Important: This registry version will not be supported in future versions of docker.
3b12ab97b20fc65a74936fb632317358845c5318ac654d768da2c98754a80906
[root@h104 ~]# echo $?
0
[root@h104 ~]# 多了一个 Consul 的镜像，容器也已经运行起来了
代码语言：javascript复制[root@h104 ~]# docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
swarm latest 81127fe5e9b4 2 weeks ago 18.11 MB
docker:5000/ci/jnkns-img latest 5b825467fc4f 7 weeks ago 708.2 MB
docker:5000/ci/jnkns-img2 latest efae71df8aca 7 weeks ago 708.2 MB
jenkins latest 5a0e442d31f6 7 weeks ago 708.4 MB
docker:5000/ubuntu latest 8693db7e8a00 8 weeks ago 187.9 MB
ubuntu latest 8693db7e8a00 8 weeks ago 187.9 MB
registry 2 683f9cd9cf88 11 weeks ago 224.5 MB
daocloud.io/daocloud/daocloud-toolset latest 1e743a7453e4 11 weeks ago 145.8 MB
hello-world latest 0a6ba66e537a 5 months ago 960 B
progrium/consul latest e66fb6787628 8 months ago 69.4 MB
<none> <none> 9f3e605442f6 8 months ago 69.4 MB
[root@h104 ~]#
[root@h104 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
3b12ab97b20f progrium/consul "/bin/start -server -" 4 minutes ago Up 4 minutes 53/tcp, 53/udp, 8300-8302/tcp, 8400/tcp, 8301-8302/udp, 0.0.0.0:8500->8500/tcp consul
236348a3c9ff docker:5000/ci/jnkns-img2 "/bin/tini -- /usr/lo" 7 weeks ago Exited (143) 4 weeks ago jenkins01
[root@h104 ~]# 
