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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 `click`
( instead of a simple start file.
:copyright: (c) 2014 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 signal
can_fork = hasattr(os, "fork")
import termcolor
except ImportError:
termcolor = None
import ssl
except ImportError:
class _SslDummy(object):
def __getattr__(self, name):
raise RuntimeError('SSL support unavailable')
ssl = _SslDummy()
def _get_openssl_crypto_module():
from OpenSSL import crypto
except ImportError:
raise TypeError('Using ad-hoc certificates requires the pyOpenSSL '
return crypto
import SocketServer as socketserver
from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
except ImportError:
import socketserver
from http.server import HTTPServer, BaseHTTPRequestHandler
ThreadingMixIn = socketserver.ThreadingMixIn
if can_fork:
ForkingMixIn = socketserver.ForkingMixIn
class ForkingMixIn(object):
# important: do not use relative imports here or python -m will break
import werkzeug
from werkzeug._internal import _log
from werkzeug._compat import PY2, WIN, reraise, wsgi_encoding_dance
from werkzeug.urls import url_parse, url_unquote
from werkzeug.exceptions import InternalServerError
can_open_by_fd = not WIN and hasattr(socket, 'fromfd')
class WSGIRequestHandler(BaseHTTPRequestHandler, object):
"""A request handler that implements WSGI dispatching."""
def server_version(self):
return 'Werkzeug/' + werkzeug.__version__
def make_environ(self):
request_url = url_parse(self.path)
def shutdown_server():
self.server.shutdown_signal = True
url_scheme = self.server.ssl_context is None and 'http' or 'https'
path_info = url_unquote(request_url.path)
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,
'werkzeug.server.shutdown': shutdown_server,
'SERVER_SOFTWARE': self.server_version,
'REQUEST_METHOD': self.command,
'PATH_INFO': wsgi_encoding_dance(path_info),
'QUERY_STRING': wsgi_encoding_dance(request_url.query),
'REMOTE_ADDR': self.address_string(),
'REMOTE_PORT': self.port_integer(),
'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 = key.upper().replace('-', '_')
if key not in ('CONTENT_TYPE', 'CONTENT_LENGTH'):
key = 'HTTP_' + key
environ[key] = value
if request_url.scheme and request_url.netloc:
environ['HTTP_HOST'] = request_url.netloc
return environ
def run_wsgi(self):
if self.headers.get('Expect', '').lower().strip() == '100-continue':
self.wfile.write(b'HTTP/1.1 100 Continue\r\n\r\n')
self.environ = 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)
except ValueError:
code, msg = status, ""
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 isinstance(data, bytes), 'applications must write bytes'
def start_response(status, response_headers, exc_info=None):
if exc_info:
if headers_sent:
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:
if not headers_sent:
if hasattr(application_iter, 'close'):
application_iter = None
except (socket.error, socket.timeout) as 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) as 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':
hdr = "%s %d %s\r\n" % (self.protocol_version, code, message)
def version_string(self):
return BaseHTTPRequestHandler.version_string(self).strip()
def address_string(self):
if getattr(self, 'environ', None):
return self.environ['REMOTE_ADDR']
return self.client_address[0]
def port_integer(self):
return self.client_address[1]
def log_request(self, code='-', size='-'):
msg = self.requestline
code = str(code)
if termcolor:
color = termcolor.colored
if code[0] == '1': # 1xx - Informational
msg = color(msg, attrs=['bold'])
if code[0] == '2': # 2xx - Success
msg = color(msg, color='white')
elif code == '304': # 304 - Resource Not Modified
msg = color(msg, color='cyan')
elif code[0] == '3': # 3xx - Redirection
msg = color(msg, color='green')
elif code == '404': # 404 - Resource Not Found
msg = color(msg, color='yellow')
elif code[0] == '4': # 4xx - Client Error
msg = color(msg, color='red', attrs=['bold'])
else: # 5xx, or any other response
msg = color(msg, color='magenta', attrs=['bold'])
self.log('info', '"%s" %s %s', msg, 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
crypto = _get_openssl_crypto_module()
# 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.maxsize))
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, 2048)
cert.sign(pkey, 'sha256')
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, 'wb') as f:
f.write(crypto.dump_certificate(crypto.FILETYPE_PEM, cert))
with open(pkey_file, 'wb') 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."""
crypto = _get_openssl_crypto_module()
import tempfile
import atexit
cert, pkey = generate_adhoc_ssl_pair()
cert_handle, cert_file = tempfile.mkstemp()
pkey_handle, pkey_file = tempfile.mkstemp()
atexit.register(os.remove, pkey_file)
atexit.register(os.remove, cert_file)
os.write(cert_handle, crypto.dump_certificate(crypto.FILETYPE_PEM, cert))
os.write(pkey_handle, crypto.dump_privatekey(crypto.FILETYPE_PEM, pkey))
ctx = load_ssl_context(cert_file, pkey_file)
return ctx
def load_ssl_context(cert_file, pkey_file=None, protocol=None):
"""Loads SSL context from cert/private key files and optional protocol.
Many parameters are directly taken from the API of
:param cert_file: Path of the certificate to use.
:param pkey_file: Path of the private key to use. If not given, the key
will be obtained from the certificate file.
:param protocol: One of the ``PROTOCOL_*`` constants in the stdlib ``ssl``
module. Defaults to ``PROTOCOL_SSLv23``.
if protocol is None:
protocol = ssl.PROTOCOL_SSLv23
ctx = _SSLContext(protocol)
ctx.load_cert_chain(cert_file, pkey_file)
return ctx
class _SSLContext(object):
'''A dummy class with a small subset of Python3's ``ssl.SSLContext``, only
intended to be used with and by Werkzeug.'''
def __init__(self, protocol):
self._protocol = protocol
self._certfile = None
self._keyfile = None
self._password = None
def load_cert_chain(self, certfile, keyfile=None, password=None):
self._certfile = certfile
self._keyfile = keyfile or certfile
self._password = password
def wrap_socket(self, sock, **kwargs):
return ssl.wrap_socket(sock, keyfile=self._keyfile,
ssl_version=self._protocol, **kwargs)
def is_ssl_error(error=None):
"""Checks if the given error (or the current one) is an SSL error."""
exc_types = (ssl.SSLError,)
from OpenSSL.SSL import Error
exc_types += (Error,)
except ImportError:
if error is None:
error = sys.exc_info()[1]
return isinstance(error, exc_types)
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.
# try:
# 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 = LISTEN_QUEUE
def __init__(self, host, port, app, handler=None,
passthrough_errors=False, ssl_context=None, fd=None):
if handler is None:
handler = WSGIRequestHandler
self.address_family = select_ip_version(host, port)
if fd is not None:
real_sock = socket.fromfd(fd, self.address_family,
port = 0
HTTPServer.__init__(self, (host, int(port)), handler) = app
self.passthrough_errors = passthrough_errors
self.shutdown_signal = False = host
self.port = self.socket.getsockname()[1]
# Patch in the original socket.
if fd is not None:
self.socket = real_sock
self.server_address = self.socket.getsockname()
if ssl_context is not None:
if isinstance(ssl_context, tuple):
ssl_context = load_ssl_context(*ssl_context)
if ssl_context == 'adhoc':
ssl_context = generate_adhoc_ssl_context()
# If we are on Python 2 the return value from socket.fromfd
# is an internal socket object but what we need for ssl wrap
# is the wrapper around it :(
sock = self.socket
if PY2 and not isinstance(sock, socket.socket):
sock = socket.socket(, sock.type, sock.proto, sock)
self.socket = ssl_context.wrap_socket(sock, server_side=True)
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()
return con, info
class ThreadedWSGIServer(ThreadingMixIn, BaseWSGIServer):
"""A WSGI server that does threading."""
multithread = True
daemon_threads = 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, fd=None):
if not can_fork:
raise ValueError('Your platform does not support forking.')
BaseWSGIServer.__init__(self, host, port, app, handler,
passthrough_errors, ssl_context, fd)
self.max_children = processes
def make_server(host=None, port=None, app=None, threaded=False, processes=1,
request_handler=None, passthrough_errors=False,
ssl_context=None, fd=None):
"""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, fd=fd)
elif processes > 1:
return ForkingWSGIServer(host, port, app, processes, request_handler,
passthrough_errors, ssl_context, fd=fd)
return BaseWSGIServer(host, port, app, request_handler,
passthrough_errors, ssl_context, fd=fd)
def is_running_from_reloader():
"""Checks if the application is running from within the Werkzeug
reloader subprocess.
.. versionadded:: 0.10
return os.environ.get('WERKZEUG_RUN_MAIN') == 'true'
def run_simple(hostname, port, application, use_reloader=False,
use_debugger=False, use_evalex=True,
extra_files=None, reloader_interval=1,
reloader_type='auto', threaded=False,
processes=1, request_handler=None, static_files=None,
passthrough_errors=False, ssl_context=None):
"""Start a WSGI application. Optional features include a reloader,
multithreading and fork support.
This function has a command-line interface too::
python -m werkzeug.serving --help
.. 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.
.. versionadded:: 0.9
Added command-line interface.
.. versionadded:: 0.10
Improved the reloader and added support for changing the backend
through the `reloader_type` parameter. See :ref:`reloader`
for more information.
: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 reloader_type: the type of reloader to use. The default is
auto detection. Valid values are ``'stat'`` and
``'watchdog'``. See :ref:`reloader` for more
:param threaded: should the process handle each request in a separate
:param processes: if greater than 1 then handle each request in a new process
up to this maximum number of concurrent processes.
: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
:class:`ssl.SSLContext`, 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 not isinstance(port, int):
raise TypeError('port must be an integer')
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 log_startup(sock):
display_hostname = hostname not in ('', '*') and hostname or 'localhost'
if ':' in display_hostname:
display_hostname = '[%s]' % display_hostname
quit_msg = '(Press CTRL+C to quit)'
port = sock.getsockname()[1]
_log('info', ' * Running on %s://%s:%d/ %s',
ssl_context is None and 'http' or 'https',
display_hostname, port, quit_msg)
def inner():
fd = int(os.environ['WERKZEUG_SERVER_FD'])
except (LookupError, ValueError):
fd = None
srv = make_server(hostname, port, application, threaded,
processes, request_handler,
passthrough_errors, ssl_context,
if fd is None:
if use_reloader:
# If we're not running already in the subprocess that is the
# reloader we want to open up a socket early to make sure the
# port is actually available.
if os.environ.get('WERKZEUG_RUN_MAIN') != 'true':
if port == 0 and not can_open_by_fd:
raise ValueError('Cannot bind to a random port with enabled '
'reloader if the Python interpreter does '
'not support socket opening by fd.')
# 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)
s = socket.socket(address_family, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((hostname, port))
if hasattr(s, 'set_inheritable'):
# If we can open the socket by file descriptor, then we can just
# reuse this one and our socket will survive the restarts.
if can_open_by_fd:
os.environ['WERKZEUG_SERVER_FD'] = str(s.fileno())
# Do not use relative imports, otherwise "python -m werkzeug.serving"
# breaks.
from werkzeug._reloader import run_with_reloader
run_with_reloader(inner, extra_files, reloader_interval,
def run_with_reloader(*args, **kwargs):
# People keep using undocumented APIs. Do not use this function
# please, we do not guarantee that it continues working.
from werkzeug._reloader import run_with_reloader
return run_with_reloader(*args, **kwargs)
def main():
'''A simple command-line interface for :py:func:`run_simple`.'''
# in contrast to argparse, this works at least under Python < 2.7
import optparse
from werkzeug.utils import import_string
parser = optparse.OptionParser(
usage='Usage: %prog [options] app_module:app_object')
parser.add_option('-b', '--bind', dest='address',
help='The hostname:port the app should listen on.')
parser.add_option('-d', '--debug', dest='use_debugger',
action='store_true', default=False,
help='Use Werkzeug\'s debugger.')
parser.add_option('-r', '--reload', dest='use_reloader',
action='store_true', default=False,
help='Reload Python process if modules change.')
options, args = parser.parse_args()
hostname, port = None, None
if options.address:
address = options.address.split(':')
hostname = address[0]
if len(address) > 1:
port = address[1]
if len(args) != 1:
sys.stdout.write('No application supplied, or too much. See --help\n')
app = import_string(args[0])
hostname=(hostname or ''), port=int(port or 5000),
application=app, use_reloader=options.use_reloader,
if __name__ == '__main__':