feat(aiohttp): allow disabling websocket compression

src/wslink/backends/aiohttp/__init__.py

@@ -17,6 +17,7 @@
 MAX_MSG_SIZE = int(os.environ.get("WSLINK_MAX_MSG_SIZE", "4194304"))
 HEART_BEAT = int(os.environ.get("WSLINK_HEART_BEAT", "30"))  # 30 seconds
 HTTP_HEADERS = os.environ.get("WSLINK_HTTP_HEADERS")  # path to json file
+WS_COMPRESS = bool(int(os.environ.get("WSLINK_WS_COMPRESS", "1")))  # permessage-deflate
 
 if HTTP_HEADERS and Path(HTTP_HEADERS).exists():
     HTTP_HEADERS = json.loads(Path(HTTP_HEADERS).read_text())
@@ -27,14 +28,15 @@
 
 
 def reload_settings():
-    global MSG_OVERHEAD, MAX_MSG_SIZE, HEART_BEAT, HTTP_HEADERS  # noqa:PLW0603
+    global MSG_OVERHEAD, MAX_MSG_SIZE, HEART_BEAT, HTTP_HEADERS, WS_COMPRESS  # noqa:PLW0603
 
     MSG_OVERHEAD = int(os.environ.get("WSLINK_MSG_OVERHEAD", MSG_OVERHEAD))
     MAX_MSG_SIZE = int(os.environ.get("WSLINK_MAX_MSG_SIZE", MAX_MSG_SIZE))
     HEART_BEAT = int(
         os.environ.get("WSLINK_HEART_BEAT", HEART_BEAT or 30)
     )  # 30 seconds
     HTTP_HEADERS = os.environ.get("WSLINK_HTTP_HEADERS", HTTP_HEADERS)
+    WS_COMPRESS = bool(int(os.environ.get("WSLINK_WS_COMPRESS", int(WS_COMPRESS))))
 
     # Allow to skip heart beat
     if HEART_BEAT < 1:
@@ -135,6 +137,11 @@ def runner(self):
     def site(self):
         return self._site
 
+    @property
+    def ws_compress(self):
+        # Explicit config wins, otherwise fall back to WSLINK_WS_COMPRESS
+        return bool(self.config.get("ws_compress", WS_COMPRESS))
+
     def get_port(self):
         """Return the actual port used by the server"""
         return self.runner.addresses[0][1]
@@ -252,7 +259,9 @@ async def disconnectClients(self):
     async def handleWsRequest(self, request):
         client_id = str(uuid.uuid4()).replace("-", "")
         current_ws = aiohttp_web.WebSocketResponse(
-            max_msg_size=MSG_OVERHEAD + MAX_MSG_SIZE, heartbeat=HEART_BEAT
+            max_msg_size=MSG_OVERHEAD + MAX_MSG_SIZE,
+            heartbeat=HEART_BEAT,
+            compress=self.web_app.ws_compress,
         )
         self.connections[client_id] = current_ws
 

src/wslink/server.py

@@ -86,6 +86,12 @@ def add_arguments(parser):
         dest="nows",
         help="If provided, disables the websocket endpoint",
     )
+    parser.add_argument(
+        "--no-ws-compress",
+        action="store_true",
+        dest="nowscompress",
+        help="If provided, disables websocket compression (permessage-deflate)",
+    )
     parser.add_argument(
         "--fs-endpoints",
         default="",
@@ -219,6 +225,10 @@ def start_webserver(
             server_config["ws"] = {}
             server_config["ws"][options.ws] = wslinkServer
 
+        # Only override WSLINK_WS_COMPRESS when explicitly requested
+        if options.nowscompress:
+            server_config["ws_compress"] = False
+
         # Configure default static route if --content requested
         if len(options.content) > 0:
             server_config["static"] = {}

tests/test_aiohttp_routes.py

@@ -5,6 +5,7 @@
 from aiohttp import web
 
 from wslink.backends.aiohttp import WebAppServer
+from wslink.websocket import ServerProtocol
 
 
 def _text_handler(text):
@@ -89,3 +90,45 @@ async def test_routes_added_before_start_take_precedence(www):
     finally:
         await server.stop()
         await task
+
+
+async def _ws_compress(port):
+    url = f"ws://localhost:{port}/ws"
+    async with (
+        aiohttp.ClientSession() as session,
+        session.ws_connect(url, compress=15) as ws,
+    ):
+        # Negotiated permessage-deflate window bits (0 => disabled)
+        compress = ws.compress
+        await ws.close()
+        return compress
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    ("env", "config", "expected"),
+    [
+        ("1", {}, True),
+        ("0", {}, False),
+        ("1", {"ws_compress": False}, False),
+        ("0", {"ws_compress": True}, True),
+    ],
+)
+async def test_ws_compression(monkeypatch, env, config, expected):
+    monkeypatch.setenv("WSLINK_WS_COMPRESS", env)
+    server = WebAppServer(
+        {
+            "host": "localhost",
+            "port": 0,
+            "timeout": 0,
+            "handle_signals": False,
+            "ws": {"ws": ServerProtocol()},
+            **config,
+        }
+    )
+    port, task = await _start(server)
+    try:
+        assert bool(await _ws_compress(port)) == expected
+    finally:
+        await server.stop()
+        await task