I have now installed Mailman 3 for production on two different servers. This is intended to be documentation of my decisions and experiences in doing so. It will be more of a narrative than a how-to, but I hope a how-to can be distilled from it.
The two servers are lists.mailman3.org (lm3o) and mail.python.org (mpo). Pre-existing things on those servers forced some decisions which were different between them, but the actual MM 3 installation was pretty much up to me, yet I did it differently the second time due to things I thought I'd learned the first time.
A fundamental step in any installation is to ensure that you have the necessary infrastructure for reliably sending mail. This mostly involves DNS records. I won't go into detail, but you need an A and maybe AAAA record for your MAIL FROM domain and rDNS PTR records for the IPs pointing back to the domain. You may also need an MX record for your email domain pointing to the Mailman server. Also good is a mechanism for DKIM signing outgoing mail and DKIM and SPF records for the domain.
This already existed on mpo, but needed to be set up on lm3o.
lm3o is the same server as mirror.list.org/mirror.mailman3.org. This is a mirror of the GNU Mailman web site and was already set up using nginx as a web server. Thus, the MM 3 installation here uses nginx as the web server proxying to gunicorn for WSGI support.
I have done a significant reinstallation on both servers. The prior version of this page is no longer applicable to these servers. I will be updating this page with more information about the current installs as time goes forward.
Both servers already had sass installed via
apt install ruby-sass
Also, the servers are both Ubuntu 14.04 and the native Python 3 is Python 3.4, so I had previously installed Python 3.6 from source. It turned out that I also couldn't install libapache2-mod-wsgi-py3 on mpo via apt because that installed a Python 3.4 version. Ultimately on mpo I installed mod_wsgi via pip, but this required re-running configure and make install for Python 3.6 because I hadn't specified --enable-shared initially and that is required to build mod_wsgi.
For these installs, I opted to install the entire Mailman suite in a virtualenv. The biggest motivation for this choice was the fact that there are already production lists on both servers and using a virtualenv allowed me to do a lot of the work in advance without interfering with the production install.
Note that all of this is done as the mailman user.
I already had some things set up in /opt/mailman including a git subdirectory containing clones of the gitlab mailman-hyperkitty, mailman, mailmanclient, hyperkitty, django-mailman3 and postorius projects.
I then created a /opt/mailman/mm directory and within that a Python 3.6 virtualenv named /opt/mailman/mm/venv. I then activated the virtualenv and did
pip install psycopg2-binary
pip install pylibmc
pip install Whoosh
on both servers. These are dependencies for using the PostgreSQL database, memcached and the Whoosh backend for HyperKitty archive search. Then because lm3o uses nginx and Gunicorn to support wsgi apps, I did
pip install gunicorn
there, and on mpo which uses Apache and mod_wsgi, I did
pip install mod_wsgi