Detect Port Conflicts in NixOS Services

bew · March 16, 2025, 11:58pm

May be time to revive that port allocator RFC?

And/or the more generic allocator RFC?

github.com/NixOS/rfcs

[RFC 0159] General purpose allocator module

NixOS:master ← lucasew:general-purpose-allocator-module

opened 04:13PM - 11 Aug 23 UTC

lucasew

+151 -0

# Summary This RFC is a rescope of #151. This RFC defines a function that …returns a customized NixOS-like module that other modules can use to ask for allocated values and the module will check for invalid or undefined values or conflicts and suggest a value that solves the issue. [Rendered](https://github.com/lucasew/rfcs/blob/general-purpose-allocator-module/rfcs/0159-general-purpose-allocator-module.md)

This Nix PR also has good inputs

github.com/NixOS/nix

builtins.port: manage dynamic port number allocation in nix

NixOS:master ← nixcloud:builtins.port

opened 05:43PM - 03 Apr 17 UTC

qknight

+15571 -0

# RFC Using `builtins.port "myIdentifierString" one can allocated a dynamic a…mount of `ports` but still be able to retrieve an assignement given a `identifier`. ``` services.nixcloud.apache.a = { enable = true; proxyOptions = { port = builtins.port "my_identifier"; path = "/"; domain = "nix.a"; }; }; ``` In the example above `port` would be assigned to `50000` and each time this `port` is referenced using `builtins.port "my_identifier"` it would return the same number `50000`. A different configuration might use `builtins.port "webserver1"` and it would return `50001` since `"my_identifier"` already uses `50000`. This PR still lacks documentation and is meant as a RFC. **Note:** I couldn't find a way to express the `builtins.port` property in `nixpkgs/lib` as `nix` does not allow state in functions. [ ] check if this is true: `eval-config.nix` can generate configurations for several VMs but `builtins.port` is global in the sense that it ignores that distinctive property, acting as a global singleton.