docs: 📝 Document Nix installation

docs/.vitepress/config.ts

@@ -36,7 +36,16 @@ export default defineConfig({
         sidebar: [
             {
                 text: "Installation",
-                link: "/setup/installation",
+                items: [
+                    {
+                        text: "Normal",
+                        link: "/setup/installation",
+                    },
+                    {
+                        text: "Nix",
+                        link: "/setup/nix",
+                    },
+                ],
             },
             {
                 text: "CLI",

docs/setup/nix.md

@@ -0,0 +1,86 @@
+# Nix Module
+
+This project is packaged as a [Nix Flake](https://nixos.wiki/wiki/Flakes), which can be used to build and run the project in a reproducible environment.
+
+## Installation
+
+### Flake-based NixOS installs
+
+Add the following to your `inputs` in your `flake.nix`:
+
+```nix
+inputs = {
+  # ...
+  versia-server = {
+    url = "github:versia-pub/server";
+    inputs.nixpkgs.follows = "nixpkgs";
+  };
+};
+```
+
+Then, add this to your `nixosConfigurations`:
+
+```nix
+nixosConfigurations = {
+  # ...
+  my-server = {
+    system = "x86_64-linux"; # arm64-linux is also supported
+    modules = [
+      # ...
+      versia-server.nixosModules.default
+    ];
+  };
+};
+```
+
+You are now ready to use the NixOS module.
+
+## Usage
+
+This module exposes the following configuration option:
+
+```nix
+services.versia-server = {
+    enable = true;
+    dataDir = "/var/lib/versia-server";
+
+    user = "versia-server";
+    group = "versia-server";
+
+    nodes = {
+        api = {
+            main = {};
+            backup = {
+                configOverrides.http.port = 2734;
+            };
+        };
+        worker = {
+            one = {};
+            two = {};
+            three = {
+                configOverrides.postgres.port = 5433;
+            };
+        }:
+    };
+
+    config = {
+        # ...
+        http = {
+            # ...
+            bind = "0.0.0.0";
+            port = 8080;
+            base_url = "https://versia.example";
+        };
+        # ...
+    };
+};
+```
+
+### Configuration Options
+
+- `enable`: Whether to enable the service. Default: `true`.
+- `dataDir`: The directory where the data will be stored. Default: `/var/lib/versia-server`.
+- `user`: The user under which the service will run. Default: `versia-server`.
+- `group`: The group under which the service will run. Default: `versia-server`.
+- `nodes`: A set of nodes to run. Each node can have its own configuration overrides, which will be merged with the default configuration. You must have at least one of each type (`api` and `worker`).
+- `config`: Contents of the config file, which is serialized to TOML. Check the Versia Server documentation for information on its contents.

flake.nix

@@ -57,8 +57,9 @@
       };
     })
     // {
-      nixosModules = {
+      nixosModules = rec {
         versia-server = import ./nix/module.nix;
+        default = versia-server;
       };
     };
 }

nix/module.nix

@@ -78,7 +78,7 @@ in {
           freeformType = configFormat.type;
           options = {};
         };
-        description = "Contents of the config file. Check the Versia Server documentation for information on its contents.";
+        description = "Contents of the config file, which is serialized to TOML. Check the Versia Server documentation for information on its contents.";
       };
     };
   };