feat: ✨ Add NixOS module

flake.nix

@@ -31,5 +31,10 @@
         inherit (pkgs) versia-server versia-server-worker;
         default = self.packages.${system}.versia-server;
       };
-    });
+    })
+    // {
+      nixosModules = {
+        versia-server = import ./nix/module.nix;
+      };
+    };
 }

nix/module.nix

@@ -0,0 +1,175 @@
+{
+  config,
+  lib,
+  pkgs,
+}: let
+  cfg = config.services.versia-server;
+  configFormat = pkgs.formats.toml {};
+  name = "versia-server";
+
+  inherit (lib.options) mkOption;
+  inherit (lib.modules) mkIf;
+in {
+  options = {
+    services.versia-server = {
+      enable = mkOption {
+        type = lib.types.bool;
+        default = false;
+        description = ''
+          Enable the Versia Server services.
+        '';
+      };
+
+      dataDir = mkOption {
+        type = lib.types.path;
+        default = "/var/lib/${name}";
+        description = ''
+          Directory where the server will store its data.
+        '';
+      };
+
+      user = mkOption {
+        type = lib.types.str;
+        default = name;
+        description = ''
+          User under which the server will run.
+        '';
+      };
+
+      group = mkOption {
+        type = lib.types.str;
+        default = name;
+        description = ''
+          Group under which the server will run.
+        '';
+      };
+
+      nodes = {
+        api = mkOption {
+          type = lib.types.attrsOf lib.types.submodule {
+            options = {
+              configOverrides = mkOption {
+                type = lib.types.submodule {
+                  freeformType = configFormat.type;
+                  options = {};
+                };
+                description = "Overrides for the node's configuration file.";
+              };
+            };
+          };
+        };
+        worker = mkOption {
+          type = lib.types.attrsOf lib.types.submodule {
+            options = {
+              configOverrides = mkOption {
+                type = lib.types.submodule {
+                  freeformType = configFormat.type;
+                  options = {};
+                };
+                description = "Overrides for the node's configuration file.";
+              };
+            };
+          };
+        };
+      };
+
+      config = mkOption {
+        type = lib.types.submodule {
+          freeformType = configFormat.type;
+          options = {};
+        };
+        description = "Contents of the config file. Check the Versia Server documentation for information on its contents.";
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = cfg.nodes.api != [];
+        message = "At least one API node must be defined.";
+      }
+      {
+        assertion = cfg.nodes.worker != [];
+        message = "At least one worker node must be defined.";
+      }
+    ];
+  };
+
+  systemd.services =
+    builtins.mapAttrs (nodeName: node: let
+      config = cfg.config // node.configOverrides;
+      configFile = builtins.toFile (configFormat.generate "config-${nodeName}" config);
+    in {
+      after = ["network-online.target"];
+      wantedBy = ["multi-user.target"];
+      requires = ["network-online.target"];
+
+      serviceConfig = {
+        Type = "simple";
+        Restart = "always";
+
+        User = cfg.user;
+        Group = cfg.group;
+
+        StateDirectory = "${name}";
+        StateDirectoryMode = "0700";
+        RuntimeDirectory = "${name}";
+        RuntimeDirectoryMode = "0700";
+
+        # Set the working directory to the data directory
+        WorkingDirectory = cfg.dataDir;
+
+        StandardOutput = "journal";
+        StandardError = "journal";
+        SyslogIdentifier = "${name}";
+
+        Environment = [
+          "CONFIG_FILE=${configFile}"
+        ];
+      };
+      path = [pkgs.versia-server];
+    }) (cfg.nodes.api ++ cfg.nodes.worker)
+    // builtins.mapAttrs (nodeName: node: let
+      type = "api";
+      exe = lib.getExe pkgs.versia-server;
+    in {
+      name = "${name}-${type}-${nodeName}";
+      description = "Versia Server ${node.name} (${type})";
+
+      serviceConfig.ExecStart = "${exe}";
+    }) (cfg.nodes.api)
+    // builtins.mapAttrs (nodeName: node: let
+      type = "worker";
+      exe = lib.getExe pkgs.versia-server-worker;
+    in {
+      name = "${name}-${type}-${nodeName}";
+      description = "Versia Server ${node.name} (${type})";
+
+      serviceConfig.ExecStart = "${exe}";
+    }) (cfg.nodes.worker);
+
+  systemd.tmpfiles.rules = [
+    {
+      # Create the data directory with the correct permissions
+      line = "d ${cfg.dataDir} - - - - ${cfg.user} ${cfg.group}";
+    }
+  ];
+
+  users = {
+    groups = {
+      "${cfg.group}" = {
+        description = "Group for the Versia Server";
+      };
+    };
+
+    users = {
+      "${cfg.user}" = {
+        isSystemUser = true;
+        group = cfg.group;
+        home = cfg.dataDir;
+        packages = [pkgs.versia-server pkgs.versia-server-worker];
+      };
+    };
+  };
+}