feat: add NixOS module for deployment

- Create nix/module.nix with comprehensive systemd service
- Support both relayOwnerNsecFile and relayOwnerNsec options
- Auto-generate nsec if neither specified
- Add security hardening (NoNewPrivileges, ProtectSystem, etc.)
- Expose as nixosModules.default and nixosModules.ngit-grasp
- Include example configuration in nix/example-configuration.nix
- Add outputHashes for nostr git dependency

3 files changed, 384 insertions, 25 deletions

diff --git a/flake.nix b/flake.nix
index 6edab71..71749b9 100644
--- a/flake.nix
+++ b/flake.nix
@@ -8,28 +8,20 @@
   };
 
   outputs = { self, nixpkgs, rust-overlay, flake-utils }:
-    flake-utils.lib.eachDefaultSystem (system:
+    (flake-utils.lib.eachDefaultSystem (system:
       let
         overlays = [ (import rust-overlay) ];
-        pkgs = import nixpkgs {
-          inherit system overlays;
-        };
-        
+        pkgs = import nixpkgs { inherit system overlays; };
+
         rustToolchain = pkgs.rust-bin.stable.latest.default.override {
           extensions = [ "rust-src" "rust-analyzer" ];
         };
-      in
-      {
+      in {
         devShells.default = pkgs.mkShell {
-          buildInputs = with pkgs; [
-            rustToolchain
-            pkg-config
-            openssl
-            git
-          ];
+          buildInputs = with pkgs; [ rustToolchain pkg-config openssl git ];
 
           RUST_SRC_PATH = "${rustToolchain}/lib/rustlib/src/rust/library";
-          
+
           shellHook = ''
             echo "🚀 ngit-grasp development environment"
             echo "Rust version: $(rustc --version)"
@@ -46,16 +38,21 @@
           pname = "ngit-grasp";
           version = "0.1.0";
           src = ./.;
-          cargoLock.lockFile = ./Cargo.lock;
-          
-          nativeBuildInputs = with pkgs; [
-            pkg-config
-          ];
-          
-          buildInputs = with pkgs; [
-            openssl
-          ];
+          cargoLock = {
+            lockFile = ./Cargo.lock;
+            outputHashes = {
+              "nostr-0.44.1" =
+                "sha256-02cawkx6bxfi3bn1sb5ws8cn9wzcwsk8cdv1vx8h8lad1jdic1qg";
+            };
+          };
+
+          nativeBuildInputs = with pkgs; [ pkg-config ];
+
+          buildInputs = with pkgs; [ openssl ];
         };
-      }
-    );
+      })) // {
+        # NixOS module for deployment
+        nixosModules.default = import ./nix/module.nix;
+        nixosModules.ngit-grasp = self.nixosModules.default;
+      };
 }
diff --git a/nix/example-configuration.nix b/nix/example-configuration.nix
new file mode 100644
index 0000000..a00d970
--- /dev/null
+++ b/nix/example-configuration.nix
@@ -0,0 +1,60 @@
+# Example NixOS configuration using ngit-grasp module
+# 
+# Usage:
+#   1. Add to your server's flake.nix inputs:
+#      inputs.ngit-grasp.url = "github:DanConwayDev/ngit-grasp";
+#
+#   2. Import the module in your configuration:
+#      imports = [ inputs.ngit-grasp.nixosModules.default ];
+#
+#   3. Configure the service (example below)
+
+{ inputs, ... }:
+
+{
+  imports = [ inputs.ngit-grasp.nixosModules.default ];
+
+  services.ngit-grasp = {
+    enable = true;
+    domain = "ngit.danconwaydev.com";
+    
+    # Network
+    bindAddress = "127.0.0.1";
+    port = 8082;  # Same port as current ngit-relay for Caddy compatibility
+    
+    # Storage (reuse existing persistent path pattern)
+    dataDir = "/persistent/ngit-danconwaydev-com-ngit-grasp";
+    
+    # Identity
+    relayName = "DanConwayDev's ngit-grasp";
+    relayDescription = "personal instance of ngit-grasp, a Rust GRASP implementation with proactive sync";
+    
+    # Option 1: Use nsec file (recommended - more secure)
+    relayOwnerNsecFile = "/persistent/ngit-danconwaydev-com-ngit-grasp/relay-owner.nsec";
+    
+    # Option 2: Inline nsec (less secure, ends up in nix store)
+    # relayOwnerNsec = "nsec1...";
+    
+    # Option 3: Auto-generate (default if neither above is set)
+    # ngit-grasp will create .relay-owner.nsec in dataDir automatically
+    
+    # Sync
+    syncBootstrapRelayUrl = "wss://relay.ngit.dev";
+    
+    # Metrics
+    metricsEnabled = true;
+    
+    # Logging
+    logLevel = "info";  # Options: trace, debug, info, warn, error
+  };
+
+  # Caddy reverse proxy (unchanged from current setup)
+  services.caddy.virtualHosts."ngit.danconwaydev.com" = {
+    extraConfig = ''
+      reverse_proxy 127.0.0.1:8082 {
+        header_down X-Real-IP {http.request.remote}
+        header_down X-Forwarded-For {http.request.remote}
+      }
+    '';
+  };
+}
diff --git a/nix/module.nix b/nix/module.nix
new file mode 100644
index 0000000..35154d2
--- /dev/null
+++ b/nix/module.nix
@@ -0,0 +1,302 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.ngit-grasp;
+
+  # Build ngit-grasp package
+  ngit-grasp = pkgs.rustPlatform.buildRustPackage {
+    pname = "ngit-grasp";
+    version = "0.1.0";
+    src = ../.;
+    cargoLock = {
+      lockFile = ../Cargo.lock;
+      outputHashes = {
+        "nostr-0.44.1" =
+          "sha256-02cawkx6bxfi3bn1sb5ws8cn9wzcwsk8cdv1vx8h8lad1jdic1qg";
+      };
+    };
+
+    nativeBuildInputs = with pkgs; [ pkg-config ];
+    buildInputs = with pkgs; [ openssl ];
+  };
+
+in {
+  options.services.ngit-grasp = {
+    enable = mkEnableOption "ngit-grasp GRASP relay";
+
+    domain = mkOption {
+      type = types.str;
+      example = "ngit.example.com";
+      description =
+        "Domain where this relay is hosted (used in GRASP validation)";
+    };
+
+    bindAddress = mkOption {
+      type = types.str;
+      default = "127.0.0.1";
+      description = "IP address to bind to";
+    };
+
+    port = mkOption {
+      type = types.port;
+      default = 8080;
+      description = "Port to listen on";
+    };
+
+    dataDir = mkOption {
+      type = types.path;
+      default = "/var/lib/ngit-grasp";
+      description = "Base directory for data storage";
+    };
+
+    relayName = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      example = "My GRASP Relay";
+      description =
+        "Relay name for NIP-11 (defaults to \${domain} grasp relay)";
+    };
+
+    relayDescription = mkOption {
+      type = types.str;
+      default = "Git Nostr Relay - a grasp implementation";
+      description = "Relay description for NIP-11";
+    };
+
+    relayOwnerNsecFile = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      example = "/persistent/ngit-grasp/relay-owner.nsec";
+      description = ''
+        Path to file containing relay owner's nsec (private key).
+        If file doesn't exist, ngit-grasp will auto-generate a random nsec and save it.
+        Takes precedence over relayOwnerNsec if both are set.
+      '';
+    };
+
+    relayOwnerNsec = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      example = "nsec1...";
+      description = ''
+        Relay owner's nsec (private key) for signing and authentication.
+        Less secure than relayOwnerNsecFile as it ends up in nix store.
+        Only used if relayOwnerNsecFile is not set.
+      '';
+    };
+
+    syncBootstrapRelayUrl = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      example = "wss://relay.ngit.dev";
+      description = "Bootstrap relay URL to sync from on startup (optional)";
+    };
+
+    databaseBackend = mkOption {
+      type = types.enum [ "lmdb" "nostr-db" "memory" ];
+      default = "lmdb";
+      description = ''
+        Database backend type:
+        - lmdb: LMDB backend (persistent, general purpose)
+        - nostr-db: NostrDB backend (persistent, optimized for Nostr)
+        - memory: In-memory database (fastest, no persistence)
+      '';
+    };
+
+    metricsEnabled = mkOption {
+      type = types.bool;
+      default = true;
+      description = "Enable Prometheus metrics endpoint at /metrics";
+    };
+
+    metricsConnectionPerIpAbuseThreshold = mkOption {
+      type = types.int;
+      default = 10;
+      description =
+        "Connections per IP before flagging as potential abuse in metrics";
+    };
+
+    metricsTopNRepos = mkOption {
+      type = types.int;
+      default = 10;
+      description = "Number of top bandwidth repos to track in metrics";
+    };
+
+    logLevel = mkOption {
+      type = types.enum [ "trace" "debug" "info" "warn" "error" ];
+      default = "info";
+      description = "Logging level for RUST_LOG environment variable";
+    };
+
+    syncMaxBackoffSecs = mkOption {
+      type = types.int;
+      default = 3600;
+      description =
+        "Maximum backoff time in seconds for sync relay reconnection (default: 1 hour)";
+    };
+
+    syncDisconnectCheckIntervalSecs = mkOption {
+      type = types.int;
+      default = 60;
+      description = "Interval in seconds for checking disconnected relays";
+    };
+
+    syncBaseBackoffSecs = mkOption {
+      type = types.int;
+      default = 5;
+      description = "Base backoff time in seconds for relay reconnection";
+    };
+
+    syncDisableNegentropy = mkOption {
+      type = types.bool;
+      default = false;
+      description = "Disable NIP-77 negentropy sync (use REQ+EOSE instead)";
+    };
+
+    rejectedHotCacheDurationSecs = mkOption {
+      type = types.int;
+      default = 120;
+      description =
+        "Hot cache duration in seconds for rejected announcements (default: 2 minutes)";
+    };
+
+    rejectedColdIndexExpirySecs = mkOption {
+      type = types.int;
+      default = 604800;
+      description =
+        "Cold index expiry in seconds for rejected announcements (default: 7 days)";
+    };
+
+    naughtyListExpirationHours = mkOption {
+      type = types.int;
+      default = 12;
+      description = "Hours before removing relay from naughty list";
+    };
+
+    user = mkOption {
+      type = types.str;
+      default = "ngit-grasp";
+      description = "User account under which ngit-grasp runs";
+    };
+
+    group = mkOption {
+      type = types.str;
+      default = "ngit-grasp";
+      description = "Group under which ngit-grasp runs";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    # Create user and group
+    users.users.${cfg.user} = {
+      isSystemUser = true;
+      group = cfg.group;
+      description = "ngit-grasp service user";
+      home = cfg.dataDir;
+    };
+
+    users.groups.${cfg.group} = { };
+
+    # Create systemd service
+    systemd.services.ngit-grasp = {
+      description = "ngit-grasp GRASP relay";
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+
+      environment = {
+        NGIT_DOMAIN = cfg.domain;
+        NGIT_BIND_ADDRESS = "${cfg.bindAddress}:${toString cfg.port}";
+        NGIT_GIT_DATA_PATH = "${cfg.dataDir}/git";
+        NGIT_RELAY_DATA_PATH = "${cfg.dataDir}/relay";
+        NGIT_RELAY_DESCRIPTION = cfg.relayDescription;
+        NGIT_DATABASE_BACKEND = cfg.databaseBackend;
+        NGIT_METRICS_CONNECTION_PER_IP_ABUSE_THRESHOLD =
+          toString cfg.metricsConnectionPerIpAbuseThreshold;
+        NGIT_METRICS_TOP_N_REPOS = toString cfg.metricsTopNRepos;
+        NGIT_SYNC_MAX_BACKOFF_SECS = toString cfg.syncMaxBackoffSecs;
+        NGIT_SYNC_DISCONNECT_CHECK_INTERVAL_SECS =
+          toString cfg.syncDisconnectCheckIntervalSecs;
+        NGIT_SYNC_BASE_BACKOFF_SECS = toString cfg.syncBaseBackoffSecs;
+        NGIT_REJECTED_HOT_CACHE_DURATION_SECS =
+          toString cfg.rejectedHotCacheDurationSecs;
+        NGIT_REJECTED_COLD_INDEX_EXPIRY_SECS =
+          toString cfg.rejectedColdIndexExpirySecs;
+        NGIT_NAUGHTY_LIST_EXPIRATION_HOURS =
+          toString cfg.naughtyListExpirationHours;
+        RUST_LOG = cfg.logLevel;
+      } // optionalAttrs (cfg.relayName != null) {
+        NGIT_RELAY_NAME = cfg.relayName;
+      } // optionalAttrs cfg.metricsEnabled { NGIT_METRICS_ENABLED = "true"; }
+        // optionalAttrs (cfg.syncBootstrapRelayUrl != null) {
+          NGIT_SYNC_BOOTSTRAP_RELAY_URL = cfg.syncBootstrapRelayUrl;
+        } // optionalAttrs cfg.syncDisableNegentropy {
+          NGIT_SYNC_DISABLE_NEGENTROPY = "true";
+        } // optionalAttrs
+        (cfg.relayOwnerNsec != null && cfg.relayOwnerNsecFile == null) {
+          # Only set inline nsec if file is not specified
+          NGIT_RELAY_OWNER_NSEC = cfg.relayOwnerNsec;
+        };
+
+      serviceConfig = {
+        Type = "simple";
+        User = cfg.user;
+        Group = cfg.group;
+
+        # Working directory where .relay-owner.nsec will be created if needed
+        WorkingDirectory = cfg.dataDir;
+
+        # Command to run
+        ExecStart = if cfg.relayOwnerNsecFile != null then
+        # Use nsec from file
+          "${ngit-grasp}/bin/ngit-grasp --relay-owner-nsec $(cat ${cfg.relayOwnerNsecFile})"
+        else
+        # Let ngit-grasp auto-generate nsec in .relay-owner.nsec file in dataDir
+          "${ngit-grasp}/bin/ngit-grasp";
+
+        # Restart policy
+        Restart = "always";
+        RestartSec = "10s";
+
+        # Hardening
+        NoNewPrivileges = true;
+        PrivateTmp = true;
+        ProtectSystem = "strict";
+        ProtectHome = true;
+        ReadWritePaths = [ cfg.dataDir ];
+
+        # If using nsecFile, grant read access
+        ReadOnlyPaths =
+          optionals (cfg.relayOwnerNsecFile != null) [ cfg.relayOwnerNsecFile ];
+
+        # Additional hardening
+        ProtectKernelTunables = true;
+        ProtectKernelModules = true;
+        ProtectControlGroups = true;
+        RestrictAddressFamilies = [ "AF_INET" "AF_INET6" "AF_UNIX" ];
+        RestrictNamespaces = true;
+        LockPersonality = true;
+        RestrictRealtime = true;
+        RestrictSUIDSGID = true;
+        PrivateDevices = true;
+
+        # Capabilities
+        CapabilityBoundingSet = "";
+        AmbientCapabilities = "";
+
+        # System call filtering
+        SystemCallFilter = [ "@system-service" "~@privileged" "~@resources" ];
+        SystemCallErrorNumber = "EPERM";
+      };
+
+      # Ensure data directories exist before starting
+      preStart = ''
+        mkdir -p ${cfg.dataDir}/git
+        mkdir -p ${cfg.dataDir}/relay
+        chown -R ${cfg.user}:${cfg.group} ${cfg.dataDir}
+        chmod 750 ${cfg.dataDir}
+      '';
+    };
+  };
+}