nixos/gitea: Support SMTP without pw in the store

[dasJ]

Motivation for this change

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

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[spacekookie]

This looks really cool 👍

[aanderse]

@GrahamcOfBorg build nixosTests.gitea

[aanderse]

@dasJ Thanks for contributing this.

@etu @Ma27 @kolaente @dasJ Someone here must be a go programmer, right? Think about how much our preStart script could be cleaned up if someone went ahead and finished implementing secret storage as per go-gitea/gitea#4860 (comment) Any takers?

[dasJ]

@aanderse you know what would scale a lot better? Something like this:

[gitea]
EXTRA_CONFIG_FILES = /var/lib/gitea/secrets.conf,/var/lib/secrets/gitea/smtp.conf

[aanderse]

@dasJ For sure. That's the title of the issue I just linked, as you have seen. I'm not asking anyone here to join the gitea dev team, though. I'm just saying that someone with sufficient go experience could probably replicate for other secrets what was done for the one.

But if you're really keen or know someone on the gitea team... please do! 😆

[kolaente]

@aanderse @dasJ As it currently stands, we'll switch to a different library for config file handling rather sooner than later since the one we're using currently (go-ini) has issues. While it would absolutly be possible to "quickly hack something together" to load more secrets from files, I would prefer to tackle this once we got rid of go-ini to do it properly/for more use cases.

(I'm one of the Gitea devs)

[aanderse]

LGTM 👍
@dasJ Thanks again!

[schmittlauch]

@dasJ I'm a bit surprised that it is possible to supply an SMTP password for the mailer, but no other required configs like the actual SMTP server to use or the username.
Are folks expected to configure this via services.gitea.extraConfig or what's the idea here?