Pick a random port number at startup (#59)

* Pick a random port at startup

DataDoc.ipynb

@@ -35,4 +35,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 5
-}
+}

datadoc/app.py

@@ -21,7 +21,7 @@
     progress_bar,
 )
 from datadoc.frontend.components.VariablesTab import get_variables_tab
-from datadoc.utils import running_in_notebook
+from datadoc.utils import running_in_notebook, pick_random_port
 
 logger = logging.getLogger(__name__)
 
@@ -90,7 +90,7 @@ def main(dataset_path: str = None):
 
         JupyterDash.infer_jupyter_proxy_config()
         app = build_app(JupyterDash)
-        app.run_server(mode="jupyterlab")
+        app.run_server(mode="jupyterlab", port=pick_random_port())
     else:
         # Assume running in server mode is better (largely for development purposes)
         logger.debug("Starting in development mode")

datadoc/utils.py

@@ -30,3 +30,12 @@ def get_display_values(
             value = value.dict()[current_language.value]
         return_dict[field_name] = value
     return return_dict
+
+
+def pick_random_port():
+    """Pick a random free port number. The function will bind a socket to port 0, and
+    a random free port from 1024 to 65535 will be selected by the operating system."""
+    import socket
+    sock = socket.socket()
+    sock.bind(('', 0))
+    return sock.getsockname()[1]