Linux运维笔记|自动化运维攻城狮

Docker 入门笔记 - Docker 网络详解

docker  

我们每启动一个docker容器，docker就会给docker容器分配一个ip,我们只要按照了docker,就会有一个网卡docker0桥接模式，使用的技术是veth-pair技术.

veth-pair 就是一对的虚拟设备接口，都是成对出现，一段连着协议，一段彼此相连

正因为有这个特性，evth-pair 充当一个桥梁，连接各种虚拟网络设备

Openstack,Docker容器之间的连接，OVS的连接，都是使用 evth-pair 技术

  • 本机和容器内网络测试是否互通
# docker0 类似于一个路由
[root@centos72 dockerfile]# ifconfig docker0
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500  
        inet 172.17.0.1  netmask 255.255.0.0  broadcast 172.17.255.255
        ether 02:42:7f:3b:be:4f  txqueuelen 0  (Ethernet)
        RX packets 300048209  bytes 53765822218 (50.0 GiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 326353914  bytes 60125182887 (55.9 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

# 容器内获取的IP地址是docker分配的`eth0: flags=4163`
[root@centos72 dockerfile]# docker exec -it  ddf2d54d0fb5 ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500  
        inet 172.17.0.2  netmask 255.255.0.0  broadcast 172.17.255.255
        ether 02:42:ac:11:00:02  txqueuelen 0  (Ethernet)
        RX packets 246  bytes 343679 (335.6 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 258  bytes 16676 (16.2 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
  • 相应服务器增加了一个vethe81ab35: flags=4163
vethe81ab35: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500  
        ether 4a:ae:15:21:13:a2  txqueuelen 0  (Ethernet)
        RX packets 264  bytes 17208 (16.8 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 252  bytes 344211 (336.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
  • 确认服务器和容器内网络是可以互通的
[root@centos72 dockerfile]# ping 172.17.0.2
PING 172.17.0.2 (172.17.0.2) 56(84) bytes of data.  
64 bytes from 172.17.0.2: icmp_seq=1 ttl=64 time=0.144 ms  
64 bytes from 172.17.0.2: icmp_seq=2 ttl=64 time=0.111 ms  
--- 172.17.0.2 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4000ms  
rtt min/avg/max/mdev = 0.074/0.107/0.144/0.027 ms
  • 再次启动一个容器，发现又多了一对网卡 vethe81ab35: flags=4163
# 启动一个新容器
# docker run -d --name mytomcat1 -p 8086:8080 leoiceo/centos7-tomcat
# 本机执行 ifconfig 
......
vethe81ab35: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500  
        ether 4a:ae:15:21:13:a2  txqueuelen 0  (Ethernet)
        RX packets 264  bytes 17208 (16.8 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 253  bytes 344253 (336.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root@centos72 ~]# docker exec -it 9bb2644dc360 ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500  
        inet 172.17.0.3  netmask 255.255.0.0  broadcast 172.17.255.255
        ether 02:42:ac:11:00:03  txqueuelen 0  (Ethernet)
        RX packets 232  bytes 344660 (336.5 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 231  bytes 14050 (13.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
  • 测试两个容器之间是否可以ping通
# 容器1： 172.17.0.2
# 容器2:  172.17.0.3
[root@ddf2d54d0fb5 ~]# ping 172.17.0.3
PING 172.17.0.3 (172.17.0.3) 56(84) bytes of data.  
64 bytes from 172.17.0.3: icmp_seq=1 ttl=64 time=0.125 ms  
^C
--- 172.17.0.3 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms  
rtt min/avg/max/mdev = 0.125/0.125/0.125/0.000 ms

容器1和容器2是公用一个路由器，docker0

所有的容器不指定网络的情况下，都是docker0路由的，docker会给我们的容器分配一个默认可用的IP

总结

Docker使用的是Linux的桥接，宿主机中是一个Dokcer容器的网桥docker0。

Docker中的所有的网络接口都是虚拟的，虚拟的转发效率高。（比如内网传递文件）

只要容器删除，对应网桥一对就没了。