I added a new module for GearBSD, it allows to define the exact list of packages you want on the system and GearBSD will take care of removing extra packages and installing missing packages. This is a huge step for me to allow managing the system from code.
Note that this is an improvement over feeding pkg_add with a package list because this method doesn't remove extra packages.
GearBSD packages in action on asciinema
In the directory openbsd/packages/ of the GearBSD git repository, edit the file Rexfile and list the packages you want in the variable @packages.
This is the packages set I want on my server.
my @packages = qw/ bwm-ng checkrestart colorls curl dkimproxy dovecot dovecot-pigeonhole duplicity ecl geomyidae git gnupg go-ipfs goaccess kermit lftp mosh mtr munin-node munin-server ncdu nginx nginx-stream opensmtpd-filter-spamassassin p5-Mail-SpamAssassin postgresql-server prosody redis rss2email rsync /;
Then, run "rex -h localhost show" to see what changes will be done like which packages will be removed and which packages will be installed.
Run "rex -h localhost configure" to apply the changes for real. I use "rex -h localhost" using a local ssh connection to root but you could run rex as root with doas with the same effect.
Installing missing packages was easy but removing extra packages was harder because you could delete packages that are still required as dependencies.
Basically, the module looks at the packages you manually installed (the one you directly installed with the pkg_add command), if they are not part of your list of packages you want to have installed, they are marked as automatically installed and then "pkg_delete -a" will remove them if they are not required by any other package.
This is a project I started yesterday but I've long think about it. I really want to be able to manage my OpenBSD system with a single configuration file. I currently wrote two modules that are independently configured, the issue is that it doesn't allow altering modules from one to another.
For example, if I create a module to install gnome3 and configure it correctly, this will require gnome3 and gnome3-packages but if you don't have them in your packages list, it will get deleted. GearBSD needs a single configuration file with all the information required by all packages, this will permit something like this:
$module{pf}{TCPports} = [ 22 ];
$module{gnome}{enable} = 1;
$module{gnome}{lang} = "fr_FR.UTF-8";
@packages = qw/catgirl firefox keepassxc/;
The module gnome will know it's enabled and that @packages has to receive gnome3 and gnome3-extras packages in order to work.
Such main configuration file will allow to catch incompatibilities like enabling gdm and xenodm at the same time.