Trying to understand Docker Networks. Docker creates the following networks automatically:
# docker network ls
NETWORK ID NAME DRIVER SCOPE
67b4afa88032 bridge bridge local
c88f997a2fa7 host host local
1df2947aad7b none null local
I understood that the bridge network represents the docker0 network present in all Docker installations, referring from the link.
Can someone help me in understanding other networks, host and none, If possible with examples?
Docker by default supports 3 networks:
1) None:
This mode will not configure any IP for the container and doesn’t have any access to the external network as well as for other containers. It does have the loopback address and can be used for running batch jobs.
# docker run -it --network=none ubuntu:14.04 /bin/bash
root@66308c6686be:/# ifconfig
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
#
# docker inspect 66308c6686be | grep -i ipaddr
"SecondaryIPAddresses": null,
"IPAddress": "",
"IPAddress": "",
2) Host
In this mode container will share the host’s network stack and all interfaces from the host will be available to the container. The container’s host name will match the host name on the host system
# docker run -it --net=host ubuntu:14.04 /bin/bash
root@labadmin-VirtualBox:/# hostname
labadmin-VirtualBox
Even the IP configuration is same as the host system's IP configuration
root@labadmin-VirtualBox:/# ip addr | grep -A 2 eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 08:00:27:b5:82:2f brd ff:ff:ff:ff:ff:ff
inet 10.0.2.15/24 brd 10.0.2.255 scope global eth0
valid_lft forever preferred_lft forever
3: lxcbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
root@labadmin-VirtualBox:/# exit
exit
HOST SYSTEM IP CONFIGURATION
# ip addr | grep -A 2 eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 08:00:27:b5:82:2f brd ff:ff:ff:ff:ff:ff
inet 10.0.2.15/24 brd 10.0.2.255 scope global eth0
valid_lft forever preferred_lft forever
3: lxcbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
In host and none mode are not configured directly but default bridge network can be configured as well as create your own user-defined bridge networks.
3) Bridge Mode
It is the Docker default networking mode which will enable the connectivity to the other interfaces of the host machine as well as among containers.
# docker run -it --network=bridge ubuntu:14.04 /bin/bash
root@58b0b1f18b2e:/# ifconfig
eth0 Link encap:Ethernet HWaddr 02:42:ac:11:00:0c
inet addr:172.17.0.12 Bcast:0.0.0.0 Mask:255.255.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:16 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2668 (2.6 KB) TX bytes:0 (0.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
Accessibility to other containers is possible in bridge mode.
root@58b0b1f18b2e:/# ping 172.17.0.11
PING 172.17.0.11 (172.17.0.11) 56(84) bytes of data.
64 bytes from 172.17.0.11: icmp_seq=1 ttl=64 time=0.143 ms
64 bytes from 172.17.0.11: icmp_seq=2 ttl=64 time=0.050 ms
Connectivity to external network.
root@58b0b1f18b2e:/# ping google.com
PING google.com (216.58.197.46) 56(84) bytes of data.
64 bytes from maa03s20-in-f46.1e100.net (216.58.197.46): icmp_seq=1 ttl=51 time=16.9 ms
Connectivity to host machine
root@labadmin-VirtualBox:~# ip a | grep eth0
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
inet 10.0.2.15/24 brd 10.0.2.255 scope global eth0
root@58b0b1f18b2e:/# ping 10.0.2.15
PING 10.0.2.15 (10.0.2.15) 56(84) bytes of data.
64 bytes from 10.0.2.15: icmp_seq=1 ttl=64 time=0.113 ms
Along with these docker provides MACVLAN network which allows to configure multiple Layer 2(MAC) addresses on a single physical interface.