lemonade

modules/nixos/services/lemonade/default.nix

@@ -0,0 +1,146 @@
+{
+  config,
+  lib,
+  pkgs,
+  namespace,
+  ...
+}:
+let
+  inherit (lib) mkForce getExe;
+  inherit (lib.${namespace}) mkModule mkOpt;
+
+  name = "lemonade";
+  cfg = config.${namespace}.services.${name};
+
+  # lemonade-server serve args built from config options
+  serveArgs = lib.concatStringsSep " " (
+    [
+      "serve"
+      "--no-tray"
+      "--port ${toString cfg.port}"
+      "--host ${cfg.host}"
+      "--log-level ${cfg.logLevel}"
+    ]
+    ++ lib.optional (cfg.maxLoadedModels != 1) "--max-loaded-models ${toString cfg.maxLoadedModels}"
+    ++ lib.optional (cfg.extraModelsDir != null) "--extra-models-dir ${cfg.extraModelsDir}"
+    ++ cfg.extraArgs
+  );
+
+  lemonadeConfig = mkModule {
+    inherit config name;
+    description = "Lemonade local LLM server";
+
+    options = {
+      # Override mkModule's default port of 80 with lemonade's actual default.
+      port = mkOpt lib.types.int 8000 "Port lemonade-router listens on";
+
+      host = mkOpt lib.types.str "127.0.0.1" "Address lemonade-router binds to";
+
+      logLevel = mkOpt (lib.types.enum [
+        "critical"
+        "error"
+        "warning"
+        "info"
+        "debug"
+        "trace"
+      ]) "info" "Log level for lemonade-router";
+
+      maxLoadedModels = mkOpt lib.types.int 1 "Maximum number of models to keep loaded simultaneously";
+
+      extraModelsDir =
+        mkOpt (lib.types.nullOr lib.types.str) null
+          "Extra directory scanned for local GGUF model files";
+
+      extraArgs =
+        mkOpt (lib.types.listOf lib.types.str) [ ]
+          "Extra arguments passed verbatim to lemonade-server serve";
+
+      modelsDir =
+        mkOpt lib.types.str "/var/lib/${name}/models"
+          "Directory where downloaded models are stored (exposed as HF_HOME)";
+
+      apiKeyFile =
+        mkOpt (lib.types.nullOr lib.types.str) null
+          "Path to a file containing the LEMONADE_API_KEY (e.g. a sops secret path)";
+    };
+
+    moduleConfig = {
+      # Install the package system-wide so lemonade-server / lemonade-router are
+      # available in PATH for interactive use alongside the daemon.
+      environment.systemPackages = [ pkgs.${namespace}.lemonade ];
+
+      systemd.services.${name} = {
+        description = "Lemonade local LLM server";
+        wantedBy = [ "multi-user.target" ];
+        after = [
+          "network.target"
+          "network-online.target"
+        ];
+        wants = [ "network-online.target" ];
+
+        # lemonade-server discover lemonade-router by reading /proc/self/exe,
+        # so we must use ExecStart with the real binary, not a shell wrapper.
+        serviceConfig = {
+          Type = "simple";
+          ExecStart = "${getExe pkgs.${namespace}.lemonade} ${serveArgs}";
+
+          User = name;
+          Group = name;
+          DynamicUser = mkForce false;
+
+          # Models and HuggingFace cache land under modelsDir.
+          # HF_HOME overrides the default ~/.cache/huggingface location.
+          Environment = [
+            "HF_HOME=${cfg.modelsDir}"
+            "XDG_RUNTIME_DIR=/run/${name}"
+          ];
+
+          # Load an API key from a secrets file if provided.
+          EnvironmentFile = lib.optional (cfg.apiKeyFile != null) cfg.apiKeyFile;
+
+          # Runtime directory for PID file / lock file (created automatically
+          # by systemd and owned by the service user).
+          RuntimeDirectory = name;
+          RuntimeDirectoryMode = "0755";
+
+          # Persistent state: models cache.
+          StateDirectory = name;
+          StateDirectoryMode = "0750";
+
+          # Home directory for the service user (needed by some HF tooling).
+          WorkingDirectory = "/var/lib/${name}";
+
+          Restart = "on-failure";
+          RestartSec = "5s";
+
+          StandardOutput = "journal";
+          StandardError = "journal";
+          SyslogIdentifier = name;
+
+          # Hardening — lemonade needs network access and subprocess execution
+          # for spawning llama.cpp / whisper.cpp backends.
+          NoNewPrivileges = true;
+          PrivateTmp = true;
+          ProtectSystem = "strict";
+          ProtectHome = true;
+          ReadWritePaths = [
+            "/var/lib/${name}"
+            "/run/${name}"
+          ];
+        };
+      };
+
+      users.users.${name} = {
+        isSystemUser = true;
+        group = name;
+        home = "/var/lib/${name}";
+        createHome = true;
+        description = "Lemonade LLM server daemon";
+      };
+      users.groups.${name} = { };
+    };
+  };
+in
+{
+  imports = [ lemonadeConfig ];
+}