Docker

Network issues with Docker

In case of network issues make sure that the mtu value of your system and the one used by docker match. Docker defaults to 1500 whereas instances running on OpenStack are often using 1450. Use ip a to detect the value of your primary interface and insert the value into /etc/docker/daemon.json.

$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1450 qdisc pfifo_fast state UP group default qlen 1000
    link/ether fa:16:3e:7a:6d:36 brd ff:ff:ff:ff:ff:ff
    inet 10.250.5.77/26 brd 10.250.5.127 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::f816:3eff:fe7a:6d36/64 scope link
       valid_lft forever preferred_lft forever<Paste>
{
      "mtu": 1450
}

See here for further information (docker-compose, etc.).