Add NixOS support (#91)

- Adds a `flake.nix` and `flake.lock`
- Updates docs on how to use them

docs/source/contributing/setup.rst

@@ -42,3 +42,22 @@ Now you're all set! Try running the development server
 
 Head on over to `http://127.0.0.1:8000 <http://127.0.0.1:8000>`_, and login
 as ``admin`` and the password you just entered.
+
+
+
+NixOS Setup
+-----------
+A ``flake.nix`` file is provided for NixOS users. To use it, first enable the redis service globally.
+Place the following in your ``/etc/nixos/configuration.nix``::
+
+  services.redis.server."".enable = true
+
+This will start a systemd service called ``redis``. After that, you can start the flake with::
+
+  nix develop
+
+You can then install dependencies, setup the database, and run the development server as described above.
+
+.. tip::
+
+   You may also need to set ``nix.settings.experimental-features = ["nix-command" "flakes"];`` in your ``configuration.nix``.

flake.nix

@@ -0,0 +1,23 @@
+{
+  description = "A flake for running Tin";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachSystem flake-utils.lib.allSystems (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = [
+            pkgs.pyenv
+            pkgs.pipenv
+            pkgs.python3
+          ];
+        };
+      });
+}