bug#47617: Docker containers retain references to the runc used

[Maxim Cournoyer]

Hello Guix!

I had this surprise today, after reconfiguring my Guix System with an
upgraded docker:

Upon attempting to run an existing container created with the previous
Docker version, I got:

--8<---------------cut here---------------start------------->8---
ERROR: for moodle-docker_db_1  Cannot start service db: Unknown runtime 
specified /gnu/store/jx64b4nnh6yvsbp117bfjc5spqz0jfq5-runc-1.0.0-rc6/sbin/runc
--8<---------------cut here---------------end--------------->8---

It seems the containers retain the exact references to the runc used,
and it somehow cause the execution to fail when it doesn't match with
the runc that the current Docker program is using.

The workaround is to destroy the containers and recreate them from
scratch on this upgraded Docker instance.

Thanks,

Maxim