Add a script for running a local dev instance of the app

(imported from commit 29813060ef17360d3a7dcc6fe1873992404457c2)

tools/run-dev.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+import subprocess
+import os
+from os import path
+
+from twisted.internet import reactor
+from twisted.web      import proxy, server, resource
+
+"""
+Starts the app listening on localhost, for local development.
+
+This script launches the Django and Tornado servers, then runs a reverse proxy
+which serves to both of them.  After it's all up and running, browse to
+
+    http://localhost:9991/
+
+Note that, while runserver and runtornado have the usual auto-restarting
+behavior, the reverse proxy itself does *not* automatically restart on changes
+to this file.
+"""
+
+proxy_port = 9991
+proxy_host = 'localhost:%d' % (proxy_port,)
+
+os.chdir(path.join(path.dirname(__file__), '..'))
+
+procs = []
+for cmd in ['python manage.py runserver  localhost:9992',
+            'python manage.py runtornado localhost:9993']:
+    procs.append(subprocess.Popen(cmd, shell=True))
+
+class Resource(resource.Resource):
+    def getChild(self, name, request):
+        request.requestHeaders.setRawHeaders('X-Forwarded-Host', [proxy_host])
+
+        if request.uri in ['/get_updates', '/api/v1/get_messages']:
+            return proxy.ReverseProxyResource('localhost', 9993, '/'+name)
+
+        return proxy.ReverseProxyResource('localhost', 9992, '/'+name)
+
+reactor.listenTCP(proxy_port, server.Site(Resource()), interface='127.0.0.1')
+
+try:
+    reactor.run()
+finally:
+    for proc in procs:
+        proc.terminate()