wait for websockify to start before starting qgis

Related to jupyterhub/jupyter-remote-desktop-proxy#105.

When QGIS starts before VNC connection is established, the QGIS process doesn't get attached to the VNC session and runs in the background.

We wait for the VNC connection to be established to make sure the QGIS GUI shows up in the VNC session.

jupyter_remote_qgis_proxy/handlers.py

@@ -1,23 +1,20 @@
-import os
-import logging
-
 from jupyter_remote_desktop_proxy.handlers import DesktopHandler
 from tornado import web
+from tornado.ioloop import IOLoop
 
-from .qgis.utils import open_qgis
-
-logging.basicConfig(level=logging.INFO)
-logger = logging.getLogger(__name__)
+from .utils import is_process_running, start_qgis
 
 
 class QgisHandler(DesktopHandler):
     @web.authenticated
     async def get(self):
-        logging.info("Starting QGIS")
+        await super().get()
         action = self.get_argument("action", None)
         url = self.get_argument("url", None)
         project_name = self.get_argument("project_name", "new project")
         layer_name = self.get_argument("layer_name", "Vector Layer")
-        if action and url:
-            open_qgis(action, url=url, project_name=project_name, layer_name=layer_name)
-        await super().get()
+
+        if not is_process_running("websockify"):
+            IOLoop.current().call_later(3, lambda:start_qgis(action, url, project_name, layer_name))
+
+

jupyter_remote_qgis_proxy/logger.py

@@ -0,0 +1,5 @@
+import logging
+
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)

jupyter_remote_qgis_proxy/qgis/scripts/zoom.py

@@ -5,6 +5,7 @@
 
 # Get the QGIS interface
 iface = qgis.utils.iface
+iface.mainWindow().showMaximized()
 
 # Get the active map canvas
 canvas = iface.mapCanvas()

jupyter_remote_qgis_proxy/qgis/utils.py

@@ -28,4 +28,4 @@ def open_qgis(action="add_vector_layer", **kwargs):
         }
         project_file_content = action_template.format(**layer_args)
         f.write(project_file_content)
-    subprocess.Popen(["qgis", "--nologo", "--project", file_path, "--code", zoom_script_path, "--code", maximize_script_path])
+    subprocess.Popen(["qgis", "--nologo", "--project", file_path, "--code", zoom_script_path])

jupyter_remote_qgis_proxy/utils.py

@@ -0,0 +1,50 @@
+import psutil
+import time
+
+from .logger import logger
+from .qgis.utils import open_qgis
+
+
+def is_process_running(process_name):
+  """
+  Checks if a process with the given name is running.
+  """
+  for process in psutil.process_iter():
+    try:
+      if process.name().lower() == process_name.lower():
+        return True
+    except (psutil.NoSuchProcess, psutil.AccessDenied):
+      pass
+  return False
+
+
+def wait_for_condition(condition, timeout=10):
+  """
+  Waits for a condition to be true for a specified timeout.
+
+  Args:
+      condition: A callable that returns True when the condition is met.
+      timeout: The maximum time in seconds to wait (default: 10).
+
+  Returns:
+      True if the condition becomes true before the timeout, False otherwise.
+  """
+  start_time = time.time()
+  while time.time() - start_time < timeout:
+    if condition():
+      return True
+    time.sleep(0.5)
+  return False
+
+
+def start_qgis(action, url, project_name, layer_name):
+    """Starts QGIS and waits for websockify to start if necessary."""
+    logger.info("Waiting for websockify to start")
+    is_websockify_running = lambda: is_process_running("websockify")
+    running = wait_for_condition(is_websockify_running, timeout=10)
+    logger.info(f"Websockify is running: {running}")
+    logger.info("Starting QGIS")
+    if action and url:
+        open_qgis(action, url=url, project_name=project_name, layer_name=layer_name)
+    elif not is_process_running("qgis"):
+        open_qgis()