Update compiler.md

[EnderturtleOrz]

Add a tip for some cases when Nix doesn't allow you to write information in /etc.

[undefined-moe]

Could you please provide more detail about this issue?
e.g screenshots, logs, etc

I'm unable to repro this error.

[EnderturtleOrz]

Here are screenshots

[undefined-moe]

maybe try nix build instead of nix-build ?

[EnderturtleOrz]

root@1d49781b4824:/home/test# nix build default.nix
error: path '/home/test/default.nix' is not a flake (because it's not a directory)

Is there something I need to change in my default.nix?

{
  system ? builtins.currentSystem,
  pkgs ? import <nixpkgs> { system = system; }
}:

pkgs.buildEnv {
  name = "hydrojudge-rootfs";
  paths = with pkgs; [
    coreutils bash diffutils nix zip unzip gcc
    (python3.withPackages (ps: with ps; [ numpy scipy ]))
  ];
  ignoreCollisions = true;
  pathsToLink = [ "/" ];
  postBuild = ''
    mkdir -p $out/buildInfo
    echo 'root:x:0:0:root:/root:/bin/bash' >$out/etc/passwd
    date > $out/buildInfo/timestamp
  '';
}

[undefined-moe]

simply use nix build github:hydro-dev/nix-channel#judge and everything should work as expected.

you can also create the following flake.nix file if you want to customize your judge environment:

{
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.11";
  inputs.flake-utils.url = "github:numtide/flake-utils";

  outputs = { self, nixpkgs, flake-utils }:
    flake-utils.lib.eachDefaultSystem (system:
      {
        packages = let
          callPackage = file: args: import file (args // { pkgs = nixpkgs.legacyPackages.${system}; system = system; });
        in {
          judge = callPackage ./judge.nix {};
        };
      }
    );
}

[EnderturtleOrz]

Thanks. I will try it the next day on our college's server. Btw, will this pr be merged? Or we just leave this pr open for further potential questions (that should be the issue)

[undefined-moe]

Currently we would suggest users to use nix flake instead of the traditional way if possible.
Nix flake introduces lock file to support managing multiple environments seperately.

[undefined-moe]

Any update for this? wonder if it works properly.

[EnderturtleOrz]

Sorry for the late response. I still got errors, largely because I am not familiar with Flake😥. Nvm, I can still build a custom environment by manually inserting passwords.