It is only a good thing to use for simple stateless daemons. It is
possible to use StateDirectory to store state, but it is extremely
limited. Notably, only service processes and root can correctly access
the state directory. This makes up for a bad practice to run maddyctl as
root what in turn screws up permissions on files in messages directory
when imap-* subcommands are used.
Migration note: Users of systemd unit with DynamicUser enabled should
move /var/lib/private/maddy to /var/lib/maddy before starting maddy
after update.
The intention is to keep to repo root clean while the list of packages
is slowly growing.
Additionally, a bunch of small (~30 LoC) files in the repo root is
merged into a single maddy.go file, for the same reason.
Most of the internal code is moved into the internal/ directory. Go
toolchain will make it impossible to import these packages from external
applications.
Some packages are renamed and moved into the pkg/ directory in the root.
According to https://github.com/golang-standards/project-layout this is
the de-facto standard to place "library code that's ok to use by
external applications" in.
To clearly define the purpose of top-level directories, README.md files
are added to each.
