Docker - 容器互联

容器互联

通过docker run命令的--link参数可以让容器之间通过连接（linking）系统进行交互。

参数格式: --link name:alias ，name是要链接的容器名称， alias是此连接的别名。

容器的连接系统会依据容器的名称，创建容器之间一个安全隧道，在启动容器的时候不使用-p和-P参数（不用映射端口到宿主主机），从而避免了暴露端口到外部网络。

通过docker run命令的--name参数来自定义容器名称（容器的名称是唯一的）。

通过docker ps命令结果的NAMES部分，查看容器名称。

Docker通过环境变量为容器公开连接信息,还添加host信息到父容器的/etc/hosts文件。

用户可以链接多个父容器到子容器。

示例

[root@CentOS-7 ~]# docker run -d --name nginx-node nginx
fc94ef26e3ab354db09323037f9a5119b18b48b8ca8c0f353ce3d3408230456d
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker run -itd --name centos-node --link nginx-node:samplelink centos
b5f56401c44d7b41f060e603b0a98309a0e996ffa66a0c177edee13364820f57
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS               NAMES
b5f56401c44d        centos              "/bin/bash"              4 seconds ago       Up 3 seconds                            centos-node
fc94ef26e3ab        nginx               "nginx -g 'daemon off"   23 seconds ago      Up 22 seconds       80/tcp, 443/tcp     nginx-node
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker inspect --format "{{ .NetworkSettings.IPAddress }}" nginx-node
172.17.0.2
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker inspect --format "{{ .NetworkSettings.IPAddress }}" centos-node
172.17.0.3
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker exec -it nginx-node env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=fc94ef26e3ab
NGINX_VERSION=1.11.13-1~jessie
HOME=/root
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker exec -it centos-node env
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=b5f56401c44d
TERM=xterm
SAMPLELINK_PORT=tcp://172.17.0.2:80
SAMPLELINK_PORT_80_TCP=tcp://172.17.0.2:80
SAMPLELINK_PORT_80_TCP_ADDR=172.17.0.2
SAMPLELINK_PORT_80_TCP_PORT=80
SAMPLELINK_PORT_80_TCP_PROTO=tcp
SAMPLELINK_PORT_443_TCP=tcp://172.17.0.2:443
SAMPLELINK_PORT_443_TCP_ADDR=172.17.0.2
SAMPLELINK_PORT_443_TCP_PORT=443
SAMPLELINK_PORT_443_TCP_PROTO=tcp
SAMPLELINK_NAME=/centos-node/samplelink
SAMPLELINK_ENV_NGINX_VERSION=1.11.13-1~jessie
HOME=/root
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker exec -it nginx-node cat /etc/hosts
127.0.0.1	localhost
::1	localhost ip6-localhost ip6-loopback
fe00::0	ip6-localnet
ff00::0	ip6-mcastprefix
ff02::1	ip6-allnodes
ff02::2	ip6-allrouters
172.17.0.2	fc94ef26e3ab
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker exec -it centos-node cat /etc/hosts
127.0.0.1	localhost
::1	localhost ip6-localhost ip6-loopback
fe00::0	ip6-localnet
ff00::0	ip6-mcastprefix
ff02::1	ip6-allnodes
ff02::2	ip6-allrouters
172.17.0.2	samplelink fc94ef26e3ab nginx-node
172.17.0.3	b5f56401c44d
[root@CentOS-7 ~]#
[root@CentOS-7 ~]# docker exec -it centos-node ping nginx-node
PING samplelink (172.17.0.2) 56(84) bytes of data.
64 bytes from samplelink (172.17.0.2): icmp_seq=1 ttl=64 time=0.339 ms
64 bytes from samplelink (172.17.0.2): icmp_seq=2 ttl=64 time=0.146 ms
^C
--- samplelink ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.146/0.242/0.339/0.097 ms
[root@CentOS-7 ~]#