实现多机容器的通信，首先须要保障容器的ip在多台虚拟机中都是惟一的。以上图为例，在192.168.205.10中新建容器，就不能再呈现容器的ip为172.17.0.3了，因为这个ip曾经在192.168.205.10中存在了。

etcd装置

为了保障容器在多机中的ip惟一，能够应用etcd，etcd是一个开源的、分布式的键值对数据存储系统

https://coreos.com/etcd/

在docker-node1上装置etcd

wget https://github.com/coreos/etcd/releases/download/v3.0.12/etcd-v3.0.12-linux-amd64.tar.gztar zxvf etcd-v3.0.12-linux-amd64.tar.gzcd etcd-v3.0.12-linux-amd64nohup ./etcd --name docker-node1 --initial-advertise-peer-urls http://192.168.205.10:2380 --listen-peer-urls http://192.168.205.10:2380 --listen-client-urls http://192.168.205.10:2379,http://127.0.0.1:2379 --advertise-client-urls http://192.168.205.10:2379 --initial-cluster-token etcd-cluster --initial-cluster docker-node1=http://192.168.205.10:2380,docker-node2=http://192.168.205.11:2380 --initial-cluster-state new &

在docker-node2上装置etcd

wget https://github.com/coreos/etcd/releases/download/v3.0.12/etcd-v3.0.12-linux-amd64.tar.gztar zxvf etcd-v3.0.12-linux-amd64.tar.gzcd etcd-v3.0.12-linux-amd64/nohup ./etcd --name docker-node2 --initial-advertise-peer-urls http://192.168.205.11:2380 --listen-peer-urls http://192.168.205.11:2380 --listen-client-urls http://192.168.205.11:2379,http://127.0.0.1:2379 --advertise-client-urls http://192.168.205.11:2379 --initial-cluster-token etcd-cluster --initial-cluster docker-node1=http://192.168.205.10:2380,docker-node2=http://192.168.205.11:2380 --initial-cluster-state new &

在docker-node1或docker-node2任一主机上查看cluster运行状态

./etcdctl cluster-healthmember 21eca106efe4caee is healthy: got healthy result from http://192.168.205.10:2379member 8614974c83d1cc6d is healthy: got healthy result from http://192.168.205.11:2379cluster is healthy

docker重启

应用 systemctl stop docker 命令，敞开docker服务后再应用如下形式重启
docker-node1

sudo /usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock --cluster-store=etcd://192.168.205.10:2379 --cluster-advertise=192.168.205.10:2375 &

docker-node2

sudo /usr/bin/dockerd -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock --cluster-store=etcd://192.168.205.11:2379 --cluster-advertise=192.168.205.11:2375 &

创立overlay network

在docker-node1上创立一个demo的overlay network

docker network create -d overlay demo

docker-node1，能够看到demo的DRIVER是overlay，SCOPE是global

[vagrant@docker-node1 etcd-v3.0.12-linux-amd64]$ docker network lsNETWORK ID NAME DRIVER SCOPE9bacf5670fa1 bridge bridge local5a8cd36174a1 demo overlay globalefb6975c8935 host host local4213425c5293 my-bridge bridge local3fa0f2e1a00b none null local

而后在docker-node2上发现会同步创立

[vagrant@docker-node2 etcd-v3.0.12-linux-amd64]$ docker network lsNETWORK ID NAME DRIVER SCOPE1c79331058ff bridge bridge local5a8cd36174a1 demo overlay global148fe990ddc5 host host local452bd665cf13 none null local

通过查看etcd的key-value，发现docker network inspect demo的内容与key-value中的内容是一样的，也就是所谓的分布式网络

[    {        "Name": "demo",        "Id": "5a8cd36174a1b37f9146aaa99de33ff20bfa8df472e07412e36048a39fe9a0e9",        "Created": "2018-07-03T09:21:08.95776633Z",        "Scope": "global",        "Driver": "overlay",        "EnableIPv6": false,        "IPAM": {            "Driver": "default",            "Options": {},            "Config": [                {                    "Subnet": "10.0.0.0/24",                    "Gateway": "10.0.0.1"                }            ]        },        "Internal": false,        "Attachable": false,        "Ingress": false,        "ConfigFrom": {            "Network": ""        },        "ConfigOnly": false,        "Containers": {},        "Options": {},        "Labels": {}    }]

测试多机通信成果

在docker-node1上

docker run -d --name test1 --network demo busybox /bin/sh -c "while true;do sleep 3600;done"

在docker-node2上如果反复执行上述命令，就会报如下谬误了，从另一方面也阐明了etcd在发挥作用

docker: Error response from daemon: Conflict. The container name "/test1" is already in use by container "14d690ada81a4510eb5dd24286d061064e8131f549dcb5320f5b5b441cc49c40". You have to remove (or rename) that container to be able to reuse that name.

能够改为

docker run -d --name test2 --network demo busybox /bin/sh -c "while true;do sleep 3600;done"

此时查看一下docker-node1与docker-node2别离对应的test1与test2容器的网络

docker network inspect demo{ "Containers": { "a9fa503852b26267d13b67067ba6c119eebcf0677f8365483b3b798dcab616a5": { "Name": "test1", "EndpointID": "3869243fcfb6a975fadf64dc31533161d2922137b18af0c3ee78c02f82b84def", "MacAddress": "", "IPv4Address": "10.0.0.2/24", "IPv6Address": "" }, "ep-8f8e30e36867c5b906bc84438049b2911660057fe031536a97efcf01d7d98699": { "Name": "test2", "EndpointID": "8f8e30e36867c5b906bc84438049b2911660057fe031536a97efcf01d7d98699", "MacAddress": "", "IPv4Address": "10.0.0.3/24", "IPv6Address": "" } }}

而后在test1上ping位于docker-node2上的test2容器是能够ping通的

docker exec test1 ping 10.0.0.3

在test2上ping位于docker-node1上的test1容器也是能够ping通的

docker exec test2 ping 10.0.0.2

胜利实现了多机容器通信的成果