fix: custom ports and host now work

src/backend/langflow/__main__.py

@@ -1,5 +1,6 @@
 import multiprocessing
 import platform
+import re
 
 from langflow.main import create_app
 
@@ -14,7 +15,38 @@ def get_number_of_workers(workers=None):
     return workers
 
 
-def serve(host: str = "127.0.0.1", workers: int = 1, timeout: int = 60):
+def replace_port(static_files_dir, host, port):
+    # Load index.html from frontend directory
+    # In it there is a script tag that sets the base url
+    # like so setItem("port", "http://localhost:7860")
+    # localhost could be anything so we need to verify for string
+    # we need to set the base url to the port that the server is running on
+    # so that the frontend can make requests to the backend
+    # This is a hacky way to do it, but it works
+    new_string = f'setItem("port","http://{host}:{port}")'
+    with open(static_files_dir / "index.html", "r") as f:
+        index_html = f.read()
+        # using regex to replace the port
+        index_html = re.sub(
+            r"setItem\(\"port\",.*\)",
+            new_string,
+            index_html,
+        )
+    with open(static_files_dir / "index.html", "w") as f:
+        f.write(index_html)
+    # Verify that the port was replaced
+    with open(static_files_dir / "index.html", "r") as f:
+        index_html = f.read()
+        if new_string not in index_html:
+            raise ValueError(
+                "The port was not replaced in index.html. "
+                "Please check the regex in main.py"
+            )
+
+
+def serve(
+    host: str = "127.0.0.1", workers: int = 1, timeout: int = 60, port: int = 7860
+):
     app = create_app()
     # get the directory of the current file
     path = Path(__file__).parent
@@ -24,7 +56,6 @@ def serve(host: str = "127.0.0.1", workers: int = 1, timeout: int = 60):
         StaticFiles(directory=static_files_dir, html=True),
         name="static",
     )
-    port = 7860
     options = {
         "bind": f"{host}:{port}",
         "workers": get_number_of_workers(workers),
@@ -32,6 +63,9 @@ def serve(host: str = "127.0.0.1", workers: int = 1, timeout: int = 60):
         "timeout": timeout,
     }
 
+    # Replace the port in index.html
+    replace_port(static_files_dir, host, port)
+
     if platform.system() in ["Darwin", "Windows"]:
         # Run using uvicorn on MacOS and Windows
         # Windows doesn't support gunicorn