Source code for cherrypy.process.servers

r"""
Starting in CherryPy 3.1, cherrypy.server is implemented as an
:ref:`Engine Plugin<plugins>`. It's an instance of
:class:`cherrypy._cpserver.Server`, which is a subclass of
:class:`cherrypy.process.servers.ServerAdapter`. The ``ServerAdapter`` class
is designed to control other servers, as well.

Multiple servers/ports
======================

If you need to start more than one HTTP server (to serve on multiple ports, or
protocols, etc.), you can manually register each one and then start them all
with engine.start::

    s1 = ServerAdapter(
        cherrypy.engine,
        MyWSGIServer(host='0.0.0.0', port=80)
    )
    s2 = ServerAdapter(
        cherrypy.engine,
        another.HTTPServer(host='127.0.0.1', SSL=True)
    )
    s1.subscribe()
    s2.subscribe()
    cherrypy.engine.start()

.. index:: SCGI

FastCGI/SCGI
============

There are also Flup\ **F**\ CGIServer and Flup\ **S**\ CGIServer classes in
:mod:`cherrypy.process.servers`. To start an fcgi server, for example,
wrap an instance of it in a ServerAdapter::

    addr = ('0.0.0.0', 4000)
    f = servers.FlupFCGIServer(application=cherrypy.tree, bindAddress=addr)
    s = servers.ServerAdapter(cherrypy.engine, httpserver=f, bind_addr=addr)
    s.subscribe()

The :doc:`cherryd</deployguide/cherryd>` startup script will do the above for
you via its `-f` flag.
Note that you need to download and install `flup <http://trac.saddi.com/flup>`_
yourself, whether you use ``cherryd`` or not.

.. _fastcgi:
.. index:: FastCGI

FastCGI
-------

A very simple setup lets your cherry run with FastCGI.
You just need the flup library,
plus a running Apache server (with ``mod_fastcgi``) or lighttpd server.

CherryPy code
^^^^^^^^^^^^^

hello.py::

    #!/usr/bin/python
    import cherrypy

    class HelloWorld:
        '''Sample request handler class.'''
        @cherrypy.expose
        def index(self):
            return "Hello world!"

    cherrypy.tree.mount(HelloWorld())
    # CherryPy autoreload must be disabled for the flup server to work
    cherrypy.config.update({'engine.autoreload.on':False})

Then run :doc:`/deployguide/cherryd` with the '-f' arg::

    cherryd -c <myconfig> -d -f -i hello.py

Apache
^^^^^^

At the top level in httpd.conf::

    FastCgiIpcDir /tmp
    FastCgiServer /path/to/cherry.fcgi -idle-timeout 120 -processes 4

And inside the relevant VirtualHost section::

    # FastCGI config
    AddHandler fastcgi-script .fcgi
    ScriptAliasMatch (.*$) /path/to/cherry.fcgi$1

Lighttpd
^^^^^^^^

For `Lighttpd <http://www.lighttpd.net/>`_ you can follow these
instructions. Within ``lighttpd.conf`` make sure ``mod_fastcgi`` is
active within ``server.modules``. Then, within your ``$HTTP["host"]``
directive, configure your fastcgi script like the following::

    $HTTP["url"] =~ "" {
      fastcgi.server = (
        "/" => (
          "script.fcgi" => (
            "bin-path" => "/path/to/your/script.fcgi",
            "socket"          => "/tmp/script.sock",
            "check-local"     => "disable",
            "disable-time"    => 1,
            "min-procs"       => 1,
            "max-procs"       => 1, # adjust as needed
          ),
        ),
      )
    } # end of $HTTP["url"] =~ "^/"

Please see `Lighttpd FastCGI Docs
<http://redmine.lighttpd.net/wiki/lighttpd/Docs:ModFastCGI>`_ for
an explanation of the possible configuration options.
"""

import os
import sys
import time
import warnings
import contextlib

import portend


[docs]class Timeouts: occupied = 5 free = 1
[docs]class ServerAdapter(object): """Adapter for an HTTP server. If you need to start more than one HTTP server (to serve on multiple ports, or protocols, etc.), you can manually register each one and then start them all with bus.start:: s1 = ServerAdapter(bus, MyWSGIServer(host='0.0.0.0', port=80)) s2 = ServerAdapter(bus, another.HTTPServer(host='127.0.0.1', SSL=True)) s1.subscribe() s2.subscribe() bus.start() """ def __init__(self, bus, httpserver=None, bind_addr=None): self.bus = bus self.httpserver = httpserver self.bind_addr = bind_addr self.interrupt = None self.running = False
[docs] def subscribe(self): self.bus.subscribe('start', self.start) self.bus.subscribe('stop', self.stop)
[docs] def unsubscribe(self): self.bus.unsubscribe('start', self.start) self.bus.unsubscribe('stop', self.stop)
[docs] def start(self): """Start the HTTP server.""" if self.running: self.bus.log('Already serving on %s' % self.description) return self.interrupt = None if not self.httpserver: raise ValueError('No HTTP server has been created.') if not os.environ.get('LISTEN_PID', None): # Start the httpserver in a new thread. if isinstance(self.bind_addr, tuple): portend.free(*self.bind_addr, timeout=Timeouts.free) import threading t = threading.Thread(target=self._start_http_thread) t.setName('HTTPServer ' + t.getName()) t.start() self.wait() self.running = True self.bus.log('Serving on %s' % self.description)
start.priority = 75 @property def description(self): """ A description about where this server is bound. """ if self.bind_addr is None: on_what = 'unknown interface (dynamic?)' elif isinstance(self.bind_addr, tuple): on_what = self._get_base() else: on_what = 'socket file: %s' % self.bind_addr return on_what def _get_base(self): if not self.httpserver: return '' host, port = self.bound_addr if getattr(self.httpserver, 'ssl_adapter', None): scheme = 'https' if port != 443: host += ':%s' % port else: scheme = 'http' if port != 80: host += ':%s' % port return '%s://%s' % (scheme, host) def _start_http_thread(self): """HTTP servers MUST be running in new threads, so that the main thread persists to receive KeyboardInterrupt's. If an exception is raised in the httpserver's thread then it's trapped here, and the bus (and therefore our httpserver) are shut down. """ try: self.httpserver.start() except KeyboardInterrupt: self.bus.log('<Ctrl-C> hit: shutting down HTTP server') self.interrupt = sys.exc_info()[1] self.bus.exit() except SystemExit: self.bus.log('SystemExit raised: shutting down HTTP server') self.interrupt = sys.exc_info()[1] self.bus.exit() raise except: self.interrupt = sys.exc_info()[1] self.bus.log('Error in HTTP server: shutting down', traceback=True, level=40) self.bus.exit() raise
[docs] def wait(self): """Wait until the HTTP server is ready to receive requests.""" while not getattr(self.httpserver, 'ready', False): if self.interrupt: raise self.interrupt time.sleep(.1) # Wait for port to be occupied if not os.environ.get('LISTEN_PID', None): # Wait for port to be occupied if not running via socket-activation # (for socket-activation the port will be managed by systemd ) if isinstance(self.bind_addr, tuple): with _safe_wait(*self.bound_addr): portend.occupied(*self.bound_addr, timeout=Timeouts.occupied)
@property def bound_addr(self): """ The bind address, or if it's an ephemeral port and the socket has been bound, return the actual port bound. """ host, port = self.bind_addr if port == 0 and self.httpserver.socket: # Bound to ephemeral port. Get the actual port allocated. port = self.httpserver.socket.getsockname()[1] return host, port
[docs] def stop(self): """Stop the HTTP server.""" if self.running: # stop() MUST block until the server is *truly* stopped. self.httpserver.stop() # Wait for the socket to be truly freed. if isinstance(self.bind_addr, tuple): portend.free(*self.bound_addr, timeout=Timeouts.free) self.running = False self.bus.log('HTTP Server %s shut down' % self.httpserver) else: self.bus.log('HTTP Server %s already shut down' % self.httpserver)
stop.priority = 25
[docs] def restart(self): """Restart the HTTP server.""" self.stop() self.start()
[docs]class FlupCGIServer(object): """Adapter for a flup.server.cgi.WSGIServer.""" def __init__(self, *args, **kwargs): self.args = args self.kwargs = kwargs self.ready = False
[docs] def start(self): """Start the CGI server.""" # We have to instantiate the server class here because its __init__ # starts a threadpool. If we do it too early, daemonize won't work. from flup.server.cgi import WSGIServer self.cgiserver = WSGIServer(*self.args, **self.kwargs) self.ready = True self.cgiserver.run()
[docs] def stop(self): """Stop the HTTP server.""" self.ready = False
[docs]class FlupFCGIServer(object): """Adapter for a flup.server.fcgi.WSGIServer.""" def __init__(self, *args, **kwargs): if kwargs.get('bindAddress', None) is None: import socket if not hasattr(socket, 'fromfd'): raise ValueError( 'Dynamic FCGI server not available on this platform. ' 'You must use a static or external one by providing a ' 'legal bindAddress.') self.args = args self.kwargs = kwargs self.ready = False
[docs] def start(self): """Start the FCGI server.""" # We have to instantiate the server class here because its __init__ # starts a threadpool. If we do it too early, daemonize won't work. from flup.server.fcgi import WSGIServer self.fcgiserver = WSGIServer(*self.args, **self.kwargs) # TODO: report this bug upstream to flup. # If we don't set _oldSIGs on Windows, we get: # File "C:\Python24\Lib\site-packages\flup\server\threadedserver.py", # line 108, in run # self._restoreSignalHandlers() # File "C:\Python24\Lib\site-packages\flup\server\threadedserver.py", # line 156, in _restoreSignalHandlers # for signum,handler in self._oldSIGs: # AttributeError: 'WSGIServer' object has no attribute '_oldSIGs' self.fcgiserver._installSignalHandlers = lambda: None self.fcgiserver._oldSIGs = [] self.ready = True self.fcgiserver.run()
[docs] def stop(self): """Stop the HTTP server.""" # Forcibly stop the fcgi server main event loop. self.fcgiserver._keepGoing = False # Force all worker threads to die off. self.fcgiserver._threadPool.maxSpare = ( self.fcgiserver._threadPool._idleCount) self.ready = False
[docs]class FlupSCGIServer(object): """Adapter for a flup.server.scgi.WSGIServer.""" def __init__(self, *args, **kwargs): self.args = args self.kwargs = kwargs self.ready = False
[docs] def start(self): """Start the SCGI server.""" # We have to instantiate the server class here because its __init__ # starts a threadpool. If we do it too early, daemonize won't work. from flup.server.scgi import WSGIServer self.scgiserver = WSGIServer(*self.args, **self.kwargs) # TODO: report this bug upstream to flup. # If we don't set _oldSIGs on Windows, we get: # File "C:\Python24\Lib\site-packages\flup\server\threadedserver.py", # line 108, in run # self._restoreSignalHandlers() # File "C:\Python24\Lib\site-packages\flup\server\threadedserver.py", # line 156, in _restoreSignalHandlers # for signum,handler in self._oldSIGs: # AttributeError: 'WSGIServer' object has no attribute '_oldSIGs' self.scgiserver._installSignalHandlers = lambda: None self.scgiserver._oldSIGs = [] self.ready = True self.scgiserver.run()
[docs] def stop(self): """Stop the HTTP server.""" self.ready = False # Forcibly stop the scgi server main event loop. self.scgiserver._keepGoing = False # Force all worker threads to die off. self.scgiserver._threadPool.maxSpare = 0
@contextlib.contextmanager def _safe_wait(host, port): """ On systems where a loopback interface is not available and the server is bound to all interfaces, it's difficult to determine whether the server is in fact occupying the port. In this case, just issue a warning and move on. See issue #1100. """ try: yield except portend.Timeout: if host == portend.client_host(host): raise msg = 'Unable to verify that the server is bound on %r' % port warnings.warn(msg)