Upgrades
I’ve been poking around the server hosting this site for the last few days and just took the time to upgrade to the latest LTS release of Ubuntu (18.04). Things went smoothly, I think — the only manual intervention required was moving php-fpm from 7.0 to 7.2, which involved only a straightforward copy of the old config files.
Just before the upgrade, I moved to a model of a separate php-fpm instance for each of the sites hosted on this server. Each one is running as it’s own user, so in theory the security guarantees should be much stronger (at most, a single site might be compromised — there should be no way to damage a second site if a first site has a vulnerability).
As always, if you notice anything amiss, please let me know.