Docker on a spinup linux host: Dealing with a Docker IPRange Conflict

Owned by Kay Ratanasaka
Last updated: Jul 01, 2020 by Darryl Wisneski (Unlicensed)
1 min read

Problem

Can I install docker on a Spinup linux host?  And how do I resolve Docker IPRange Conflicts?

Solution

dockerd and docker-compose IPRange conflicts

Dockerd and docker-compose by default use the 172.17.x.x IP space, which conflicts with important Yale campus resources, including the Yale VPN.

If using the Docker official repo, it will have created a docker0 interface with a 172.17.x.x interface, e.g.


$ netstat -nr | grep '172.17'
172.17.0.0 0.0.0.0 255.255.0.0 U 0 0 0 docker0


This overlaps with campus Yale networks, and causes routing to fail if you are certain ITS VPNs. The fix is to change the default network used by the Docker interface and docker-compose.

DNO reserved networks:

10.221.31.0/24

10.221.32.0/22


$ sudo su -
$ cat << EOF >> /etc/docker/daemon.json
{
"bip": "10.221.31.1/24",
"fixed-cidr": "10.221.31.1/25","default-address-pools": [
{"base":"10.221.32.0/22", "size":24}
]

}
EOF

Restart docker:

$ sudo systemctl restart docker


Then restart docker-compose:

$ sudo docker-compose down

$ sudo docker-compose up


You may need to reboot your Spinup virtual machine to clear any lingering entries in the system's network routing table in order for the fix to take effect.

The ifconfig output should resemble the following:

$ ifconfig
br-353d062c6792: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 10.221.32.1 netmask 255.255.255.0 broadcast 10.222.0.255
inet6 fe80::42:28ff:fe92:8b0d prefixlen 64 scopeid 0x20<link>
ether 02:42:28:92:8b:0d txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 11 bytes 906 (906.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

docker0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 10.221.31.1 netmask 255.255.255.0 broadcast 10.221.31.255
ether 02:42:ba:bb:7f:23 txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0


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