Puma 4 is no longer maintained, and Puma 5 removed the option to run
Puma as as daemon. That means that, in order to upgrade, we need to rely
in a process monitoring tool. We're using systemd because it's installed
by default in most (all?) operating systems running Consul Democracy on
production and it's supported by both Puma and the capistrano3-puma gem.
Using systemd means Puma will be automatically started whenever it
crashes, so we no longer need the changes done in commit 40b3c9f2c and
we can now use the default tasks configuration in capistrano3-puma and
capistrano3-delayed-job.
Since Puma is also started automatically when booting the system, we
don't need a cron job to do so anymore and can remove it from the
`schedule.rb` file.
Since Puma 5.x will remove support for running Puma as a daemon,
capistrano-puma requires defining whether we want to run Puma as a
daemon (as we've been doing so far with Puma 4.x) or to uses systemd.
We'll change this code to uses systemd when upgrading to Puma 5.x.
The task `deploy:restart` was doing nothing since we moved from unicorn
to puma.
Now we're also restarting delayed jobs on `deploy:restart`, which is
probably what's expected in most cases.
Puma is the server we use in the development environment, so this way we
don't need to maintain two servers. Furthermore, puma seems to offer a
few advantages over unicorn (like multithreading) and no disadvantages.
