transmission: use freeformType on settings and various fixes

[ju1m]

Motivation for this change

Leveraging freeformType on services.transmission.settings.

Things done

• Move settings assertions to options.
• Alias option port to settings.rpc-port.
• Alias option openFirewall to openPeerPorts.
• Add option openRPCPort.
• Add option settings.trash-original-torrent-files.
• Add mkDefaults when setting boot.kernel.sysctl.
• Use <xref linkend="opt-services.transmission.${optionName}"/> in descriptions.
• Fix transmission: systemctl reload transmission fails with Permissioned denied #135695 by removing the InaccessiblePaths= on the RootDirectory='s path.
• Remove SystemCallErrorNumber=EPERM which may silent failures to call a disallowed syscalls instead of failing hard with an ESYS, that will enable us to know more easily if we need to relax the SystemCallFilter= (using coredumpctl debug to know which syscall failed).
• Fix watch-dir creation.

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• 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 nixpkgs-review --run "nixpkgs-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.

[aanderse]

openFirewall is a pretty standard option name across modules. Do we want to leave it in as an alias?

[infinisil]

@aanderse There's different options for different ports now, openPeerPorts and openRPCPort. I think it makes sense to not use openFirewall to avoid confusion.

[aanderse]

@aanderse There's different options for different ports now, openPeerPorts and openRPCPort. I think it makes sense to not use openFirewall to avoid confusion.

I hadn't seen a PR adding that. Great news. I'll look into it 👍 Oh I see... OK 👍

[infinisil]

In addition to the things below, the descriptions of options downloadDirPermissions and home can be updated to reference the new options.

Also as another improvement to this module: There's homeDir defined in a let in at the top which can be removed (its usages need to be fixed though).

[ju1m]

In addition to the things below, the descriptions of options downloadDirPermissions and home can be updated to reference the new options.

Done.

Also as another improvement to this module: There's homeDir defined in a let in at the top which can be removed (its usages need to be fixed though).

Done.

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/379

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/585

[picnoir]

LGTM.

I don't see any obvious migration pitfall here apart from what's already been addressed.

Tested on my personal deployment.

I'll leave it there for 7 days before merging to let @infinisil perform a second pass if he feels like it.

[picnoir]

I'd be nice to have some VM tests for this module.

Edit: There are some VM tests, see nixos/tests/bittorent.nix.

[ju1m]

• Rebase after the merge of transmission: fix error when watch-dir is enabled #139128