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# -*- coding: utf-8 -*-
There are many ways to serve a WSGI application. While you're developing
it you usually don't want a full blown webserver like Apache but a simple
standalone one. From Python 2.5 onwards there is the `wsgiref`_ server in
the standard library. If you're using older versions of Python you can
download the package from the cheeseshop.
However there are some caveats. Sourcecode won't reload itself when
changed and each time you kill the server using ``^C`` you get an
`KeyboardInterrupt` error. While the latter is easy to solve the first
one can be a pain in the ass in some situations.
The easiest way is creating a small ```` that runs the
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from myproject import make_app
from werkzeug.serving import run_simple
app = make_app(...)
run_simple('localhost', 8080, app, use_reloader=True)
You can also pass it a `extra_files` keyword argument with a list of
additional files (like configuration files) you want to observe.
For bigger applications you should consider using `werkzeug.script`
instead of a simple start file.
:copyright: (c) 2011 by the Werkzeug Team, see AUTHORS for more details.
:license: BSD, see LICENSE for more details.
from __future__ import with_statement
import os
import socket
import sys
import time
import thread
import signal
import subprocess
from urllib import unquote
from SocketServer import ThreadingMixIn, ForkingMixIn
from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
import werkzeug
from werkzeug._internal import _log
from werkzeug.exceptions import InternalServerError
class WSGIRequestHandler(BaseHTTPRequestHandler, object):
"""A request handler that implements WSGI dispatching."""
def server_version(self):
return 'Werkzeug/' + werkzeug.__version__
def make_environ(self):
if '?' in self.path:
path_info, query = self.path.split('?', 1)
path_info = self.path
query = ''
def shutdown_server():
self.server.shutdown_signal = True
url_scheme = self.server.ssl_context is None and 'http' or 'https'
environ = {
'wsgi.version': (1, 0),
'wsgi.url_scheme': url_scheme,
'wsgi.input': self.rfile,
'wsgi.errors': sys.stderr,
'wsgi.multithread': self.server.multithread,
'wsgi.multiprocess': self.server.multiprocess,
'wsgi.run_once': False,
'SERVER_SOFTWARE': self.server_version,
'REQUEST_METHOD': self.command,
'PATH_INFO': unquote(path_info),
'QUERY_STRING': query,
'CONTENT_TYPE': self.headers.get('Content-Type', ''),
'CONTENT_LENGTH': self.headers.get('Content-Length', ''),
'REMOTE_ADDR': self.client_address[0],
'REMOTE_PORT': self.client_address[1],
'SERVER_NAME': self.server.server_address[0],
'SERVER_PORT': str(self.server.server_address[1]),
'SERVER_PROTOCOL': self.request_version
for key, value in self.headers.items():
key = 'HTTP_' + key.upper().replace('-', '_')
environ[key] = value
return environ
def run_wsgi(self):
app =
environ = self.make_environ()
headers_set = []
headers_sent = []
def write(data):
assert headers_set, 'write() before start_response'
if not headers_sent:
status, response_headers = headers_sent[:] = headers_set
code, msg = status.split(None, 1)
self.send_response(int(code), msg)
header_keys = set()
for key, value in response_headers:
self.send_header(key, value)
key = key.lower()
if 'content-length' not in header_keys:
self.close_connection = True
self.send_header('Connection', 'close')
if 'server' not in header_keys:
self.send_header('Server', self.version_string())
if 'date' not in header_keys:
self.send_header('Date', self.date_time_string())
assert type(data) is str, 'applications must write bytes'
def start_response(status, response_headers, exc_info=None):
if exc_info:
if headers_sent:
raise exc_info[0], exc_info[1], exc_info[2]
exc_info = None
elif headers_set:
raise AssertionError('Headers already set')
headers_set[:] = [status, response_headers]
return write
def execute(app):
application_iter = app(environ, start_response)
for data in application_iter:
# make sure the headers are sent
if not headers_sent:
if hasattr(application_iter, 'close'):
application_iter = None
except (socket.error, socket.timeout), e:
self.connection_dropped(e, environ)
except Exception:
if self.server.passthrough_errors:
from werkzeug.debug.tbtools import get_current_traceback
traceback = get_current_traceback(ignore_system_exceptions=True)
# if we haven't yet sent the headers but they are set
# we roll back to be able to set them again.
if not headers_sent:
del headers_set[:]
except Exception:
self.server.log('error', 'Error on request:\n%s',
def handle(self):
"""Handles a request ignoring dropped connections."""
rv = None
rv = BaseHTTPRequestHandler.handle(self)
except (socket.error, socket.timeout), e:
except Exception:
if self.server.ssl_context is None or not is_ssl_error():
if self.server.shutdown_signal:
return rv
def initiate_shutdown(self):
"""A horrible, horrible way to kill the server for Python 2.6 and
later. It's the best we can do.
# Windows does not provide SIGKILL, go with SIGTERM then.
sig = getattr(signal, 'SIGKILL', signal.SIGTERM)
# reloader active
if os.environ.get('WERKZEUG_RUN_MAIN') == 'true':
os.kill(os.getpid(), sig)
# python 2.7
self.server._BaseServer__shutdown_request = True
# python 2.6
self.server._BaseServer__serving = False
def connection_dropped(self, error, environ=None):
"""Called if the connection was closed by the client. By default
nothing happens.
def handle_one_request(self):
"""Handle a single HTTP request."""
self.raw_requestline = self.rfile.readline()
if not self.raw_requestline:
self.close_connection = 1
elif self.parse_request():
return self.run_wsgi()
def send_response(self, code, message=None):
"""Send the response header and log the response code."""
if message is None:
message = code in self.responses and self.responses[code][0] or ''
if self.request_version != 'HTTP/0.9':
self.wfile.write("%s %d %s\r\n" %
(self.protocol_version, code, message))
def version_string(self):
return BaseHTTPRequestHandler.version_string(self).strip()
def address_string(self):
return self.client_address[0]
def log_request(self, code='-', size='-'):
self.log('info', '"%s" %s %s', self.requestline, code, size)
def log_error(self, *args):
self.log('error', *args)
def log_message(self, format, *args):
self.log('info', format, *args)
def log(self, type, message, *args):
_log(type, '%s - - [%s] %s\n' % (self.address_string(),
message % args))
#: backwards compatible name if someone is subclassing it
BaseRequestHandler = WSGIRequestHandler
def generate_adhoc_ssl_pair(cn=None):
from random import random
from OpenSSL import crypto
# pretty damn sure that this is not actually accepted by anyone
if cn is None:
cn = '*'
cert = crypto.X509()
cert.set_serial_number(int(random() * sys.maxint))
cert.gmtime_adj_notAfter(60 * 60 * 24 * 365)
subject = cert.get_subject()
subject.CN = cn
subject.O = 'Dummy Certificate'
issuer = cert.get_issuer()
issuer.CN = 'Untrusted Authority'
issuer.O = 'Self-Signed'
pkey = crypto.PKey()
pkey.generate_key(crypto.TYPE_RSA, 768)
cert.sign(pkey, 'md5')
return cert, pkey
def make_ssl_devcert(base_path, host=None, cn=None):
"""Creates an SSL key for development. This should be used instead of
the ``'adhoc'`` key which generates a new cert on each server start.
It accepts a path for where it should store the key and cert and
either a host or CN. If a host is given it will use the CN
For more information see :func:`run_simple`.
.. versionadded:: 0.9
:param base_path: the path to the certificate and key. The extension
``.crt`` is added for the certificate, ``.key`` is
added for the key.
:param host: the name of the host. This can be used as an alternative
for the `cn`.
:param cn: the `CN` to use.
from OpenSSL import crypto
if host is not None:
cn = '*.%s/CN=%s' % (host, host)
cert, pkey = generate_adhoc_ssl_pair(cn=cn)
cert_file = base_path + '.crt'
pkey_file = base_path + '.key'
with open(cert_file, 'w') as f:
f.write(crypto.dump_certificate(crypto.FILETYPE_PEM, cert))
with open(pkey_file, 'w') as f:
f.write(crypto.dump_privatekey(crypto.FILETYPE_PEM, pkey))
return cert_file, pkey_file
def generate_adhoc_ssl_context():
"""Generates an adhoc SSL context for the development server."""
from OpenSSL import SSL
pkey, cert = generate_adhoc_ssl_pair()
ctx = SSL.Context(SSL.SSLv23_METHOD)
return ctx
def load_ssl_context(cert_file, pkey_file):
"""Loads an SSL context from a certificate and private key file."""
from OpenSSL import SSL
ctx = SSL.Context(SSL.SSLv23_METHOD)
return ctx
def is_ssl_error(error=None):
"""Checks if the given error (or the current one) is an SSL error."""
if error is None:
error = sys.exc_info()[1]
from OpenSSL import SSL
return isinstance(error, SSL.Error)
class _SSLConnectionFix(object):
"""Wrapper around SSL connection to provide a working makefile()."""
def __init__(self, con):
self._con = con
def makefile(self, mode, bufsize):
return socket._fileobject(self._con, mode, bufsize)
def __getattr__(self, attrib):
return getattr(self._con, attrib)
def shutdown(self, arg=None):
def select_ip_version(host, port):
"""Returns AF_INET4 or AF_INET6 depending on where to connect to."""
# disabled due to problems with current ipv6 implementations
# and various operating systems. Probably this code also is
# not supposed to work, but I can't come up with any other
# ways to implement this.
## info = socket.getaddrinfo(host, port, socket.AF_UNSPEC,
## socket.SOCK_STREAM, 0,
## socket.AI_PASSIVE)
## if info:
## return info[0][0]
##except socket.gaierror:
## pass
if ':' in host and hasattr(socket, 'AF_INET6'):
return socket.AF_INET6
return socket.AF_INET
class BaseWSGIServer(HTTPServer, object):
"""Simple single-threaded, single-process WSGI server."""
multithread = False
multiprocess = False
request_queue_size = 128
def __init__(self, host, port, app, handler=None,
passthrough_errors=False, ssl_context=None):
if handler is None:
handler = WSGIRequestHandler
self.address_family = select_ip_version(host, port)
HTTPServer.__init__(self, (host, int(port)), handler) = app
self.passthrough_errors = passthrough_errors
self.shutdown_signal = False
if ssl_context is not None:
from OpenSSL import tsafe
except ImportError:
raise TypeError('SSL is not available if the OpenSSL '
'library is not installed.')
if isinstance(ssl_context, tuple):
ssl_context = load_ssl_context(*ssl_context)
if ssl_context == 'adhoc':
ssl_context = generate_adhoc_ssl_context()
self.socket = tsafe.Connection(ssl_context, self.socket)
self.ssl_context = ssl_context
self.ssl_context = None
def log(self, type, message, *args):
_log(type, message, *args)
def serve_forever(self):
self.shutdown_signal = False
except KeyboardInterrupt:
def handle_error(self, request, client_address):
if self.passthrough_errors:
return HTTPServer.handle_error(self, request, client_address)
def get_request(self):
con, info = self.socket.accept()
if self.ssl_context is not None:
con = _SSLConnectionFix(con)
return con, info
class ThreadedWSGIServer(ThreadingMixIn, BaseWSGIServer):
"""A WSGI server that does threading."""
multithread = True
class ForkingWSGIServer(ForkingMixIn, BaseWSGIServer):
"""A WSGI server that does forking."""
multiprocess = True
def __init__(self, host, port, app, processes=40, handler=None,
passthrough_errors=False, ssl_context=None):
BaseWSGIServer.__init__(self, host, port, app, handler,
passthrough_errors, ssl_context)
self.max_children = processes
def make_server(host, port, app=None, threaded=False, processes=1,
request_handler=None, passthrough_errors=False,
"""Create a new server instance that is either threaded, or forks
or just processes one request after another.
if threaded and processes > 1:
raise ValueError("cannot have a multithreaded and "
"multi process server.")
elif threaded:
return ThreadedWSGIServer(host, port, app, request_handler,
passthrough_errors, ssl_context)
elif processes > 1:
return ForkingWSGIServer(host, port, app, processes, request_handler,
passthrough_errors, ssl_context)
return BaseWSGIServer(host, port, app, request_handler,
passthrough_errors, ssl_context)
def _iter_module_files():
for module in sys.modules.values():
filename = getattr(module, '__file__', None)
if filename:
old = None
while not os.path.isfile(filename):
old = filename
filename = os.path.dirname(filename)
if filename == old:
if filename[-4:] in ('.pyc', '.pyo'):
filename = filename[:-1]
yield filename
def _reloader_stat_loop(extra_files=None, interval=1):
"""When this function is run from the main thread, it will force other
threads to exit when any modules currently loaded change.
Copyright notice. This function is based on the from
the CherryPy trac which originated from WSGIKit which is now dead.
:param extra_files: a list of additional files it should watch.
from itertools import chain
mtimes = {}
while 1:
for filename in chain(_iter_module_files(), extra_files or ()):
mtime = os.stat(filename).st_mtime
except OSError:
old_time = mtimes.get(filename)
if old_time is None:
mtimes[filename] = mtime
elif mtime > old_time:
_log('info', ' * Detected change in %r, reloading' % filename)
def _reloader_inotify(extra_files=None, interval=None):
# Mutated by inotify loop when changes occur.
changed = [False]
# Setup inotify watches
from pyinotify import WatchManager, Notifier
# this API changed at one point, support both
from pyinotify import EventsCodes as ec
except (ImportError, AttributeError):
import pyinotify as ec
wm = WatchManager()
def signal_changed(event):
if changed[0]:
_log('info', ' * Detected change in %r, reloading' % event.path)
changed[:] = [True]
for fname in extra_files or ():
wm.add_watch(fname, mask, signal_changed)
# ... And now we wait...
notif = Notifier(wm)
while not changed[0]:
# always reiterate through sys.modules, adding them
for fname in _iter_module_files():
wm.add_watch(fname, mask, signal_changed)
if notif.check_events(timeout=interval):
# TODO Set timeout to something small and check parent liveliness
# currently we always use the stat loop reloader for the simple reason
# that the inotify one does not respond to added files properly. Also
# it's quite buggy and the API is a mess.
reloader_loop = _reloader_stat_loop
def restart_with_reloader():
"""Spawn a new Python interpreter with the same arguments as this one,
but running the reloader thread.
while 1:
_log('info', ' * Restarting with reloader')
args = [sys.executable] + sys.argv
new_environ = os.environ.copy()
new_environ['WERKZEUG_RUN_MAIN'] = 'true'
# a weird bug on windows. sometimes unicode strings end up in the
# environment and does not like this, encode them
# to latin1 and continue.
if == 'nt':
for key, value in new_environ.iteritems():
if isinstance(value, unicode):
new_environ[key] = value.encode('iso-8859-1')
exit_code =, env=new_environ)
if exit_code != 3:
return exit_code
def run_with_reloader(main_func, extra_files=None, interval=1):
"""Run the given function in an independent python interpreter."""
import signal
signal.signal(signal.SIGTERM, lambda *args: sys.exit(0))
if os.environ.get('WERKZEUG_RUN_MAIN') == 'true':
thread.start_new_thread(main_func, ())
reloader_loop(extra_files, interval)
except KeyboardInterrupt:
except KeyboardInterrupt:
def run_simple(hostname, port, application, use_reloader=False,
use_debugger=False, use_evalex=True,
extra_files=None, reloader_interval=1, threaded=False,
processes=1, request_handler=None, static_files=None,
passthrough_errors=False, ssl_context=None):
"""Start an application using wsgiref and with an optional reloader. This
wraps `wsgiref` to fix the wrong default reporting of the multithreaded
WSGI variable and adds optional multithreading and fork support.
.. versionadded:: 0.5
`static_files` was added to simplify serving of static files as well
as `passthrough_errors`.
.. versionadded:: 0.6
support for SSL was added.
.. versionadded:: 0.8
Added support for automatically loading a SSL context from certificate
file and private key.
:param hostname: The host for the application. eg: ``'localhost'``
:param port: The port for the server. eg: ``8080``
:param application: the WSGI application to execute
:param use_reloader: should the server automatically restart the python
process if modules were changed?
:param use_debugger: should the werkzeug debugging system be used?
:param use_evalex: should the exception evaluation feature be enabled?
:param extra_files: a list of files the reloader should watch
additionally to the modules. For example configuration
:param reloader_interval: the interval for the reloader in seconds.
:param threaded: should the process handle each request in a separate
:param processes: number of processes to spawn.
:param request_handler: optional parameter that can be used to replace
the default one. You can use this to replace it
with a different
:param static_files: a dict of paths for static files. This works exactly
like :class:`SharedDataMiddleware`, it's actually
just wrapping the application in that middleware before
:param passthrough_errors: set this to `True` to disable the error catching.
This means that the server will die on errors but
it can be useful to hook debuggers in (pdb etc.)
:param ssl_context: an SSL context for the connection. Either an OpenSSL
context, a tuple in the form ``(cert_file, pkey_file)``,
the string ``'adhoc'`` if the server should
automatically create one, or `None` to disable SSL
(which is the default).
if use_debugger:
from werkzeug.debug import DebuggedApplication
application = DebuggedApplication(application, use_evalex)
if static_files:
from werkzeug.wsgi import SharedDataMiddleware
application = SharedDataMiddleware(application, static_files)
def inner():
make_server(hostname, port, application, threaded,
processes, request_handler,
passthrough_errors, ssl_context).serve_forever()
if os.environ.get('WERKZEUG_RUN_MAIN') != 'true':
display_hostname = hostname != '*' and hostname or 'localhost'
if ':' in display_hostname:
display_hostname = '[%s]' % display_hostname
_log('info', ' * Running on %s://%s:%d/', ssl_context is None
and 'http' or 'https', display_hostname, port)
if use_reloader:
# Create and destroy a socket so that any exceptions are raised before
# we spawn a separate Python interpreter and lose this ability.
address_family = select_ip_version(hostname, port)
test_socket = socket.socket(address_family, socket.SOCK_STREAM)
test_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
test_socket.bind((hostname, port))
run_with_reloader(inner, extra_files, reloader_interval)
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