Stephen,

I can't help with containered versions - I don't play docker if I can help it! From what I do know it shouldn't be too hard to docker-compose: alpine base image + python venv + data dir. Perhaps something like Claude Sonnet could help you?

I do have an Ansible role which can install mailman3 well enough:

https://github.com/rivimey/ansible-mailman3

I have found upgrading between versions relatively painless apart from the situation when the host python disappears under its feet when you do a dist-upgrade. My recommendation is to get all the non-python files copied over to the new VM, install the venv, run the 'migrates' for django, and see from there.

Regards,

Ruth

As an aside: I find that my mailman3 relatively frequently (as in once a month or so) fails to start properly because it can fail in a way systemd is unable to/doesn't know it needs/ to restart it. I run this script in cron to catch that:

#!/bin/bash
#

fn=/tmp/mm$$
trap "rm -f $fn" exit term

systemctl status mailman3-core >$fn
if grep -q 'Active: active (running)' $fn ; then
     exit
fi

sleep 10
sudo systemctl restart mailman3-core

sleep 5
echo =-=-=-= >>$fn
systemctl status mailman3-core >>$fn
if grep -q 'Active: active (running)' $fn ; then
     mailx -s 'Mailman3 systemctl status: restarted' root@ivimey.org
<$fn
     exit
fi

mailx -s 'Mailman3 systemctl status: failure' root@ivimey.org <$fn
exit 1

I used to use this script, set to run by systemctl as an 'on boot' service, but the systemctl restart above seems to be sufficient at the moment:

The systemd service file (presumes mailman3 is run using the name mailman3-core, which might not be true for you):

[Unit]
Description=Unlock Mailman3 if system crashed and left lock files around
Wants=mailman3-core.service
Before=mailman3-core.service multi-user.target
After=basic.target
RefuseManualStart=true

[Service]
Type=simple
ExecStart=/usr/local/bin/mailman3-unlock.sh
Restart=no
KillMode=process

[Install]
WantedBy=multi-user.target

And the bash shell script referenced by the service. As you can see it checks to see if mailman is actually running before killing any locks! (presumes a location for the mailman3 installation, which is unlikely to be true for you):

#!/bin/sh
# Carefully unlock mailman3 in the case that it wasn't shut down
properly.
# If the lock files are left, mailman3 will refuse to start up.

# See if there is a mailman3 master process running... if so, unlocking
# is unsafe.
nprocs=$(ps ax |grep mailman3/bin/master |grep -v grep |wc -l)
if [ "$nprocs" -eq 0 ] ; then
   if [ -f /opt/mailman3/var/core/master.lck ]; then
     echo "mailman3-unlock: lock files found, unlocked" |
systemd-cat -p warning
     rm -f /opt/mailman3/var/core/master.lck*
   else
     echo "mailman3-unlock: no locks" | systemd-cat -p info
   fi
else
   echo "mailman3-unlock: mailman3 is already running!" |
systemd-cat -p warning
   exit 1
fi

exit 0

-- Software Manager & Engineer Tel: 01223 414180 Blog:http://www.ivimey.org/blog