Docker, vpn and /etc/resolv.conf

Today I encounter a strange issue with /etc/resolv.conf, while working with Docker on my company's VPN.

When openconnect sets up the VPN, it modifies /etc/resolv.conf, as expected. The funny thing is that if I now ran docker run <something>, docker would change /etc/resolv.conf back to its original value; it wouldn't even restore the "vpn" version upon exit.

After much head scratching, I figured that maybe, the problem was that openconnect and docker were messing with different network interfaces, therefore conflicting when writing their version of /etc/resolv.conf.

I installed resolvconf, which is able to manage exactly this scenario and, boom!, it's fixed! I couldn't find an answer in Google, so I am posting my solution here, in case somebody has the same issue.