Nixpkgs: nixos/taskserver: Firewall is opened on all interfaces

[tilpner]

Describe the bug

If services.taskserver.listenHost is changed from its default value of localhost, the module sets

networking.firewall.allowedTCPPorts = [ cfg.listenPort ];

This option is interface-agnostic, and doesn't allow the user to restrict access to a single
interface easily.

Expected behavior

There should be a way to allow access on only some interfaces, even if listenHost was set.

Some modules have an openFirewall option, which would solve this nicely. With a default of true, backwards compatibility would be kept.

I'll send a PR if that sounds good.

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module: services.taskserver.listenHost

cc @aszlig

[aszlig]

@tilpner: In addition to that option, I'd probably go for deprecation, removing the allowedTCPPorts definition entirely from the module and not open up those ports at all. The latter should be explicitly set by the user.

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[tilpner]

Well, I never fixed it, so it's still a problem. :(