1 files changed, 104 insertions, 0 deletions
diff --git a/nixpkgs/nixos/modules/misc/version.nix b/nixpkgs/nixos/modules/misc/version.nix
new file mode 100644
index 000000000000..c576cf4cb925
--- /dev/null
+++ b/nixpkgs/nixos/modules/misc/version.nix
@@ -0,0 +1,104 @@
+{ options, 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. <literal>16.03.1160.f2d4ee1</literal>).";
+    };
+
+    nixos.release = mkOption {
+      readOnly = true;
+      type = types.str;
+      default = trivial.release;
+      description = "The NixOS release (e.g. <literal>16.03</literal>).";
+    };
+
+    nixos.versionSuffix = mkOption {
+      internal = true;
+      type = types.str;
+      default = trivial.versionSuffix;
+      description = "The NixOS version suffix (e.g. <literal>1160.f2d4ee1</literal>).";
+    };
+
+    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. <literal>Emu</literal>).";
+    };
+
+    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/"
+        SUPPORT_URL="https://nixos.org/nixos/support.html"
+        BUG_REPORT_URL="https://github.com/NixOS/nixpkgs/issues"
+      '';
+
+  };
+
+}