Store the host config in a per-host config file.

remoting/tools/me2me_virtual_host.py

 #!/usr/bin/env python
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Virtual Me2Me implementation.  This script runs and manages the processes
 # required for a Virtual Me2Me desktop, which are: X server, X desktop
 # session, and Host process.
 # This script is intended to run continuously as a background daemon
 # process, running under an ordinary (non-root) user account.
@@ skipping 11 matching lines @@
 import time
 import urllib2
 import uuid
 
 # Local modules
 import gaia_auth
 import keygen
 
 REMOTING_COMMAND = "remoting_me2me_host"
 
+# Command-line switch for passing the config path to remoting_me2me_host.
+HOST_CONFIG_SWITCH_NAME = "host-config"
+
 SCRIPT_PATH = os.path.dirname(sys.argv[0])
 if not SCRIPT_PATH:
   SCRIPT_PATH = os.getcwd()
 
 # These are relative to SCRIPT_PATH.
 EXE_PATHS_TO_TRY = [
     ".",
     "../../out/Debug",
     "../../out/Release"
 ]
@@ skipping 211 matching lines @@
       logging.info("Xvfb is active.")
 
   def launch_x_session(self):
     # Start desktop session
     session_proc = subprocess.Popen("/etc/X11/Xsession",
                                     cwd=os.environ["HOME"],
                                     env=self.child_env)
     if not session_proc.pid:
       raise Exception("Could not start X session")
 
-  def launch_host(self):
+  def launch_host(self, host):
     # Start remoting host
-    command = locate_executable(REMOTING_COMMAND)
-    self.host_proc = subprocess.Popen(command, env=self.child_env)
+    args = [locate_executable(REMOTING_COMMAND),
+            "--%s=%s" % (HOST_CONFIG_SWITCH_NAME, host.config_file)]

[Wez, 2011/12/10 00:00:09]

Is it possible for |config_file| to contain anything that might confuse popen()?
 (see below)

[Lambros, 2011/12/10 02:00:31]

This shouldn't confuse popen(), because the whole --%s=%s constitutes a single
item of the args[] list, with no shell parsing involved.  And
remoting_me2me_host ought to parse everything from the first '=' to the end of
that args[] item as the filename.

+    self.host_proc = subprocess.Popen(args, env=self.child_env)
     if not self.host_proc.pid:
       raise Exception("Could not start remoting host")
 
 
 def main():
   atexit.register(cleanup)
 
   for s in [signal.SIGINT, signal.SIGTERM]:
     signal.signal(s, signal_handler)
 
   # Ensure full path to config directory exists.
   if not os.path.exists(CONFIG_DIR):
     os.makedirs(CONFIG_DIR, mode=0700)
 
   auth = Authentication(os.path.join(CONFIG_DIR, "auth.json"))
   if not auth.load_config():
     try:
       auth.refresh_tokens()
     except:
       logging.error("Authentication failed.")
       return 1
     auth.save_config()
 
-  host = Host(os.path.join(CONFIG_DIR, "host.json"))
+  host = Host(os.path.join(CONFIG_DIR, "host#%s.json" % socket.gethostname()))

[Wez, 2011/12/10 00:00:09]

Is socket.gethostname() reliable, e.g. if the host has multiple names do we
always get the first?  (I think so, but I'm not sure...)

Can host names contain anything we'd be scared to have routed into a file path? 
Perhaps we should use a hash of the name, rather than the name itself?

[Lambros, 2011/12/10 02:00:31]

Python doc isn't helpful here, it says only that it returns the machine's
hostname.  socket.getfqdn() may be better, I'm not sure.
Yeah.  The gotcha is that hostnames can be 255 chars long, which is also the
limit for UNIX filenames.  The allowed characters for hostnames (alphanum, dash,
dot) are OK here.  The problem is just the maximum length :)

Done.

 
   if not host.load_config():
     host.create_config(auth)
     host.save_config()
 
   logging.info("Using host_id: " + host.host_id)
 
   desktop = Desktop()
   desktop.launch_x_server()
   desktop.launch_x_session()
-  desktop.launch_host()
+  desktop.launch_host(host)
 
   while True:
     pid, status = os.wait()
     logging.info("wait() returned (%s,%s)" % (pid, status))
 
     if pid == desktop.x_proc.pid:
       logging.info("X server process terminated with code %d", status)
       break
 
     if pid == desktop.host_proc.pid:
       logging.info("Host process terminated, relaunching")
-      desktop.launch_host()
+      desktop.launch_host(host)
 
 if __name__ == "__main__":
   logging.basicConfig(level=logging.DEBUG)
   sys.exit(main())