{ config, lib, pkgs, ... }: with lib; let cfg = config.system.nixos; gitRepo = "${toString pkgs.path}/.git"; gitCommitId = lib.substring 0 7 (commitIdFromGitRepo gitRepo); in { options.system = { nixos.version = mkOption { internal = true; type = types.str; description = "The full NixOS version (e.g. 16.03.1160.f2d4ee1)."; }; nixos.release = mkOption { readOnly = true; type = types.str; default = trivial.release; description = "The NixOS release (e.g. 16.03)."; }; nixos.versionSuffix = mkOption { internal = true; type = types.str; default = trivial.versionSuffix; description = "The NixOS version suffix (e.g. 1160.f2d4ee1)."; }; nixos.revision = mkOption { internal = true; type = types.str; default = trivial.revisionWithDefault "master"; description = "The Git revision from which this NixOS configuration was built."; }; nixos.codeName = mkOption { readOnly = true; type = types.str; default = trivial.codeName; description = "The NixOS release code name (e.g. Emu)."; }; stateVersion = mkOption { type = types.str; default = cfg.release; description = '' Every once in a while, a new NixOS release may change configuration defaults in a way incompatible with stateful data. For instance, if the default version of PostgreSQL changes, the new version will probably be unable to read your existing databases. To prevent such breakage, you can set the value of this option to the NixOS release with which you want to be compatible. The effect is that NixOS will option defaults corresponding to the specified release (such as using an older version of PostgreSQL). ''; }; defaultChannel = mkOption { internal = true; type = types.str; default = https://nixos.org/channels/nixos-unstable; description = "Default NixOS channel to which the root user is subscribed."; }; }; config = { system.nixos = { # These defaults are set here rather than up there so that # changing them would not rebuild the manual version = mkDefault (cfg.release + cfg.versionSuffix); revision = mkIf (pathIsDirectory gitRepo) (mkDefault gitCommitId); versionSuffix = mkIf (pathIsDirectory gitRepo) (mkDefault (".git." + gitCommitId)); }; # Generate /etc/os-release. See # https://www.freedesktop.org/software/systemd/man/os-release.html for the # format. environment.etc."os-release".text = '' NAME=NixOS ID=nixos VERSION="${cfg.version} (${cfg.codeName})" VERSION_CODENAME=${toLower cfg.codeName} VERSION_ID="${cfg.version}" PRETTY_NAME="NixOS ${cfg.version} (${cfg.codeName})" LOGO="nix-snowflake" HOME_URL="https://nixos.org/" DOCUMENTATION_URL="https://nixos.org/nixos/manual/index.html" SUPPORT_URL="https://nixos.org/nixos/support.html" BUG_REPORT_URL="https://github.com/NixOS/nixpkgs/issues" ''; }; }