My default nix configuration on NixOS.
  
This configuration is more for building/debugging stuff and caching with
nix-serve.
Usually my package version is locked since different
versions of
nix can have some effects.
{ config, ... }:
{
  nix = {
    package = (import ../versions.nix).nix_2_17 { inherit config; };
    settings = {
      log-lines = 25;                                # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-log-lines
      fallback = true;                               # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-fallback
      tarball-ttl = 0;                               # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-tarball-ttl
      show-trace = true;                             # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-show-trace
      connect-timeout = 5;                           # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-connect-timeout
      auto-optimise-store = true;                    # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-auto-optimise-store
      narinfo-cache-negative-ttl = 0;                # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-narinfo-cache-negative-ttl
      narinfo-cache-positive-ttl = 0;                # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-narinfo-cache-positive-ttl
      builders-use-substitutes = true;               # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-builders-use-substitutes
      min-free = 268435456;                          # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-min-free (256 MB in Bytes)
      max-free = 1073741824;                         # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-max-free (1 GB in Bytes)
      allowed-users = [ "root" "@wheel" ];           # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-allowed-users
      trusted-users = [ "root" "@wheel" ];           # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-trusted-users
      experimental-features = "nix-command flakes";  # https://nixos.org/manual/nix/unstable/command-ref/conf-file.html#conf-experimental-features
    };
  };
}