feat(nginx): add rate limiting with per-domain overrides

- Global rate limit: 10 req/s with burst of 20
- Connection limit: 30 concurrent per IP
- Per-domain override support (requests, burst, enable/disable)
- SearXNG gets higher limits (20/40) to tolerate bot traffic
- Returns 429 when rate limited

configuration.nix

@@ -101,11 +101,19 @@
   myModules.nginx = {
     enable = true;
     email = "info@ashisgreat.xyz";
+    rateLimit = {
+      enable = true;
+      requests = 10;
+      burst = 20;
+    };
     domains = {
       "search.ashisgreat.xyz" = {
         port = 8888;
         # SearXNG sets its own CSP in settings.yml — omit at Nginx level to avoid conflicts
         contentSecurityPolicy = null;
+        # Search engine — slightly more permissive for bot traffic
+        rateLimit.requests = 20;
+        rateLimit.burst = 40;
       };
     };
   };

modules/nginx.nix

@@ -1,5 +1,5 @@
 # Nginx Reverse Proxy Module
-# Provides: Nginx with automatic Let's Encrypt certificates and security headers
+# Provides: Nginx with automatic Let's Encrypt certificates, security headers, and rate limiting
 #
 # Usage:
 #   myModules.nginx = {
@@ -32,6 +32,28 @@ in
       description = "Email address for Let's Encrypt registration";
     };
 
+    rateLimit = {
+      enable = lib.mkEnableOption "Nginx rate limiting";
+
+      zone = lib.mkOption {
+        type = lib.types.str;
+        default = "10m";
+        description = "Size of the shared memory zone for rate limiting";
+      };
+
+      requests = lib.mkOption {
+        type = lib.types.int;
+        default = 10;
+        description = "Number of requests allowed per second (burst applies on top)";
+      };
+
+      burst = lib.mkOption {
+        type = lib.types.int;
+        default = 20;
+        description = "Maximum burst of requests allowed beyond the rate";
+      };
+    };
+
     domains = lib.mkOption {
       type = lib.types.attrsOf (lib.types.submodule {
         options = {
@@ -52,6 +74,26 @@ in
             description = "Content-Security-Policy header value. Set to null to omit.";
           };
 
+          rateLimit = {
+            enable = lib.mkOption {
+              type = lib.types.nullOr lib.types.bool;
+              default = null;
+              description = "Enable rate limiting for this vhost. Defaults to global rateLimit.enable.";
+            };
+
+            requests = lib.mkOption {
+              type = lib.types.nullOr lib.types.int;
+              default = null;
+              description = "Requests per second for this vhost. Defaults to global rateLimit.requests.";
+            };
+
+            burst = lib.mkOption {
+              type = lib.types.nullOr lib.types.int;
+              default = null;
+              description = "Burst size for this vhost. Defaults to global rateLimit.burst.";
+            };
+          };
+
           extraLocations = lib.mkOption {
             type = lib.types.attrsOf (lib.types.submodule {
               options = {
@@ -98,6 +140,14 @@ in
       recommendedProxySettings = true;
       recommendedTlsSettings = true;
 
+      # Rate limiting zones (one per domain for per-domain limits)
+      commonHttpConfig = lib.optionalString cfg.rateLimit.enable ''
+        # Global rate limiting zone
+        limit_req_zone $binary_remote_addr zone=global:10m rate=${toString cfg.rateLimit.requests}r/s;
+        # Limit connection flooding
+        limit_conn_zone $binary_remote_addr zone=connlimit:10m;
+      '';
+
       virtualHosts = lib.mapAttrs' (domain: opts: {
         name = domain;
         value = {
@@ -127,7 +177,12 @@ in
           locations = {
             "/" = {
               proxyPass = "http://127.0.0.1:${toString opts.port}";
-              extraConfig = opts.extraConfig;
+              extraConfig = opts.extraConfig + lib.optionalString (if opts.rateLimit.enable != null then opts.rateLimit.enable else cfg.rateLimit.enable) ''
+                # Rate limiting
+                limit_req zone=global burst=${toString (if opts.rateLimit.burst != null then opts.rateLimit.burst else cfg.rateLimit.burst)} nodelay;
+                limit_conn connlimit 30;
+                limit_req_status 429;
+              '';
             };
           } // lib.mapAttrs' (locPath: locOpts: {
             name = locPath;