Allow vpython to be used remotely on a headless Pi

README.md

@@ -92,3 +92,12 @@ If you execute build_original_no_overload.py, and change the statement "if True:
 Note that in site-packages/vpython/vpython_libraries it is glowcomm.html that is used by launchers such as idle or spyder; glowcomm.js is used with Jupyter notebook (and a modified version is used in Jupyterlab).
 
 Placing console.log(....) statements in the GlowScript code or in the JavaScript section of glowcomm.html can be useful in debugging. You may also need to put debugging statements into site-packages/vpython/vpython.py.
+
+
+## Environment options
+
+The following options make sense for running VPython in a headless environment:
+
+* VPYTHON_PORT -> Specify the TCP/IP port number for the HTTP server.
+* VPYTHON_NOBROWSER -> Set this to disable trying to launch a browser.
+    The link will be printed instead.

vpython/no_notebook.py

@@ -14,13 +14,15 @@
 import copy
 import socket
 import multiprocessing
+import logging
 
 
 import signal
 from urllib.parse import unquote
 
 from .rate_control import rate
 
+logger = logging.getLogger(__name__)
 
 # Redefine `Thread.run` to not show a traceback for Spyder when stopping
 # the server by raising a KeyboardInterrupt or SystemExit.
@@ -64,7 +66,7 @@ def find_free_port():
     return s.getsockname()[1]
 
 
-__HTTP_PORT = find_free_port()
+__HTTP_PORT = int(os.getenv("VPYTHON_PORT", find_free_port()))
 __SOCKET_PORT = find_free_port()
 
 try:
@@ -119,6 +121,7 @@ class serveHTTP(BaseHTTPRequestHandler):
              'ico': ['image/x-icon', serverdata]}
 
     def do_GET(self):
+        logger.debug("Doing get")
         global httpserving
         httpserving = True
         html = False
@@ -135,6 +138,7 @@ def do_GET(self):
             mime = self.mimes[fext]
             # For example, mime[0] is image/jpg,
             # mime[1] is C:\Users\Bruce\Anaconda3\lib\site-packages\vpython\vpython_data
+            logger.debug("Sending response")
             self.send_response(200)
             self.send_header('Content-type', mime[0])
             self.end_headers()
@@ -153,6 +157,7 @@ def do_GET(self):
                 self.wfile.write(glowcomm.encode('utf-8'))
 
     def log_message(self, format, *args):  # this overrides server stderr output
+        logger.debug(format, *args)
         return
 
 # Requests from client to websocket server can be the following:
@@ -245,25 +250,34 @@ def onClose(self, wasClean, code, reason):
         else:
             os.kill(os.getpid(), signal.SIGINT)
 
+logger.info("Creating server")
 
 try:
     if platform.python_implementation() == 'PyPy':
-        server_address = ('', 0)      # let HTTPServer choose a free port
+        server_address = ('', int(os.getenv("VPYTHON_PORT", 0)))      # let HTTPServer choose a free port
         __server = HTTPServer(server_address, serveHTTP)
         port = __server.server_port   # get the chosen port
         # Change the global variable to store the actual port used
         __HTTP_PORT = port
-        _webbrowser.open('http://localhost:{}'.format(port)
-                         )  # or webbrowser.open_new_tab()
+        url = 'http://localhost:{}'.format(__HTTP_PORT)
+        if os.getenv("VPYTHON_NOBROWSER"):
+            print(url)
+        else:
+            _webbrowser.open(url)  # or webbrowser.open_new_tab()
     else:
         __server = HTTPServer(('', __HTTP_PORT), serveHTTP)
-        # or webbrowser.open_new_tab()
-        if _browsertype == 'default':  # uses default browser
-            _webbrowser.open('http://localhost:{}'.format(__HTTP_PORT))
+
+        url = 'http://localhost:{}'.format(__HTTP_PORT)
+        if os.getenv("VPYTHON_NOBROWSER"):
+            print(url)
+        else:
+            if _browsertype == 'default':  # uses default browser
+                _webbrowser.open(url)         # or webbrowser.open_new_tab()
 
 except:
     pass
 
+logger.info("Server created")
 
 if _browsertype == 'pyqt':
     if platform.python_implementation() == 'PyPy':
@@ -287,15 +301,15 @@ def start_Qapp(port):
     filename = filepath + '/qtbrowser.py'
     os.system('python ' + filename + ' http://localhost:{}'.format(port))
 
-
+logger.info("Starting serve forever loop")
 # create a browser in its own process
 if _browsertype == 'pyqt':
     __m = multiprocessing.Process(target=start_Qapp, args=(__HTTP_PORT,))
     __m.start()
 
 __w = threading.Thread(target=__server.serve_forever)
 __w.start()
-
+logger.info("Started")
 
 def start_websocket_server():
     """
@@ -322,13 +336,13 @@ def start_websocket_server():
     __interact_loop.run_until_complete(__coro)
     __interact_loop.run_forever()
 
-
+logger.debug("Starting WS server")
 # Put the websocket server in a separate thread running its own event loop.
 # That works even if some other program (e.g. spyder) already running an
 # async event loop.
 __t = threading.Thread(target=start_websocket_server)
 __t.start()
-
+logger.debug("WS Started")
 
 def stop_server():
     """Shuts down all threads and exits cleanly."""

vpython/vpython_libraries/glowcomm.html

@@ -58,7 +58,15 @@
     "use strict";
 
 	//var sock = socket_port() // created by no_notebook.py
-	ws = new WebSocket("ws://localhost:"+sock)
+    let ws_url;
+    if (document.location.hostname.includes("localhost")){
+      ws_url = "ws://localhost:"+sock;
+    }
+    else {
+      ws_url = 'ws://' + document.location.hostname + ":" + sock;
+    }
+
+	ws = new WebSocket(ws_url);
 	ws.binaryType = "arraybuffer";
 
 	ws.onopen = function() {