Thanks for your interest! Here's some notes on why this is developed in the way it is.
Why is diff used for config files?
We like using the latest version of software. Using diffs to create the final config files means that it should work just fine if a developer adds a new line to the config file, removes a line, etc. If we tried to just bundle a working config file wholesale (as ircd-irc2 does), then every update we'd need to recreate the config file from scratch.
How do I update the diffs?
Grab a new copy of the software (new git clone, etc). Than apply the patch the same way the Dockerfile does. Then update the file, and then create a new patch. For a standard git patch this would look like:
git clone blahblah ircd-src
cd ircd-src
git apply ~/path/to/test-servers/server/ircd-config.patch
vim doc/ircd.conf.example
git diff > ~/path/to/test-servers/server/ircd-config.patchWhy do some allow TLS and some not?
Some server software just doesn't provide the ability to use TLS. On some, I'm simply a little lazy. It's not super necessary regardless, and I mostly want to provide it to test things like TLS IRCv3 capabilities and the like.
Would you allow contributions?
Sure! Right now we have a licensing question to work out, but once that's sorted I'd love to see this get extended with better images and more images.
Why do this?
Plain and simple, to provide a decent base for IRC server testing software to use. No need to go configure a bunch of servers from scratch or something else, I can just use these images and get a reasonable, well-configured machine that should let me test whatever I need to.