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wsgi.py
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wsgi.py
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# Copyright 2010 OpenStack LLC.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Utility methods for working with WSGI servers
"""
import datetime
import errno
import json
import logging
import os
import signal
import sys
import time
import eventlet
from eventlet.green import socket, ssl
import eventlet.greenio
import eventlet.wsgi
import routes
import routes.middleware
import webob.dec
import webob.exc
from glance.common import exception
from glance.common import utils
from glance.openstack.common import cfg
import glance.openstack.common.log as os_logging
bind_opts = [
cfg.StrOpt('bind_host', default='0.0.0.0'),
cfg.IntOpt('bind_port'),
]
socket_opts = [
cfg.IntOpt('backlog', default=4096),
cfg.IntOpt('tcp_keepidle', default=600),
cfg.StrOpt('ca_file'),
cfg.StrOpt('cert_file'),
cfg.StrOpt('key_file'),
]
workers_opt = cfg.IntOpt('workers', default=0)
CONF = cfg.CONF
CONF.register_opts(bind_opts)
CONF.register_opts(socket_opts)
CONF.register_opt(workers_opt)
class WritableLogger(object):
"""A thin wrapper that responds to `write` and logs."""
def __init__(self, logger, level=logging.DEBUG):
self.logger = logger
self.level = level
def write(self, msg):
self.logger.log(self.level, msg.strip("\n"))
def get_bind_addr(default_port=None):
"""Return the host and port to bind to."""
return (CONF.bind_host, CONF.bind_port or default_port)
def get_socket(default_port):
"""
Bind socket to bind ip:port in conf
note: Mostly comes from Swift with a few small changes...
:param default_port: port to bind to if none is specified in conf
:returns : a socket object as returned from socket.listen or
ssl.wrap_socket if conf specifies cert_file
"""
bind_addr = get_bind_addr(default_port)
# TODO(jaypipes): eventlet's greened socket module does not actually
# support IPv6 in getaddrinfo(). We need to get around this in the
# future or monitor upstream for a fix
address_family = [addr[0] for addr in socket.getaddrinfo(bind_addr[0],
bind_addr[1], socket.AF_UNSPEC, socket.SOCK_STREAM)
if addr[0] in (socket.AF_INET, socket.AF_INET6)][0]
cert_file = CONF.cert_file
key_file = CONF.key_file
use_ssl = cert_file or key_file
if use_ssl and (not cert_file or not key_file):
raise RuntimeError(_("When running server in SSL mode, you must "
"specify both a cert_file and key_file "
"option value in your configuration file"))
def wrap_ssl(sock):
ssl_kwargs = {
'server_side': True,
'certfile': cert_file,
'keyfile': key_file,
'cert_reqs': ssl.CERT_NONE,
}
if CONF.ca_file:
ssl_kwargs['ca_certs'] = CONF.ca_file
ssl_kwargs['cert_reqs'] = ssl.CERT_REQUIRED
return ssl.wrap_socket(sock, **ssl_kwargs)
sock = None
retry_until = time.time() + 30
while not sock and time.time() < retry_until:
try:
sock = eventlet.listen(bind_addr,
backlog=CONF.backlog,
family=address_family)
if use_ssl:
sock = wrap_ssl(sock)
except socket.error, err:
if err.args[0] != errno.EADDRINUSE:
raise
eventlet.sleep(0.1)
if not sock:
raise RuntimeError(_("Could not bind to %s:%s after trying for 30 "
"seconds") % bind_addr)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# in my experience, sockets can hang around forever without keepalive
sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
# This option isn't available in the OS X version of eventlet
if hasattr(socket, 'TCP_KEEPIDLE'):
sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE,
CONF.tcp_keepidle)
return sock
class Server(object):
"""Server class to manage multiple WSGI sockets and applications."""
def __init__(self, threads=1000):
self.threads = threads
self.children = []
self.running = True
def start(self, application, default_port):
"""
Run a WSGI server with the given application.
:param application: A function that can be called with no arguments
that will return the application to run in the WSGI server
:param default_port: Port to bind to if none is specified in conf
"""
def kill_children(*args):
"""Kills the entire process group."""
self.logger.error(_('SIGTERM or SIGINT received'))
signal.signal(signal.SIGTERM, signal.SIG_IGN)
signal.signal(signal.SIGINT, signal.SIG_IGN)
self.running = False
os.killpg(0, signal.SIGTERM)
def hup(*args):
"""
Shuts down the server, but allows running requests to complete
"""
self.logger.error(_('SIGHUP received'))
signal.signal(signal.SIGHUP, signal.SIG_IGN)
self.running = False
self.app_func = application
self.sock = get_socket(default_port)
os.umask(027) # ensure files are created with the correct privileges
self.logger = os_logging.getLogger('eventlet.wsgi.server')
if CONF.workers == 0:
# Useful for profiling, test, debug etc.
self.pool = self.create_pool()
self.pool.spawn_n(self._single_run, self.app_func(), self.sock)
return
else:
self.logger.info(_("Starting %d workers") % CONF.workers)
signal.signal(signal.SIGTERM, kill_children)
signal.signal(signal.SIGINT, kill_children)
signal.signal(signal.SIGHUP, hup)
while len(self.children) < CONF.workers:
self.run_child()
def create_pool(self):
eventlet.patcher.monkey_patch(all=False, socket=True)
return eventlet.GreenPool(size=self.threads)
def wait_on_children(self):
while self.running:
try:
pid, status = os.wait()
if os.WIFEXITED(status) or os.WIFSIGNALED(status):
self.logger.error(_('Removing dead child %s') % pid)
self.children.remove(pid)
if os.WIFEXITED(status) and os.WEXITSTATUS(status) == 2:
self.logger.error(_('Not respawning child %d, cannot '
'recover from termination') % pid)
if not self.children:
self.logger.error(
_('All workers have terminated. Exiting'))
self.running = False
else:
self.run_child()
except OSError, err:
if err.errno not in (errno.EINTR, errno.ECHILD):
raise
except KeyboardInterrupt:
self.logger.info(_('Caught keyboard interrupt. Exiting.'))
break
eventlet.greenio.shutdown_safe(self.sock)
self.sock.close()
self.logger.debug(_('Exited'))
def wait(self):
"""Wait until all servers have completed running."""
try:
if self.children:
self.wait_on_children()
else:
self.pool.waitall()
except KeyboardInterrupt:
pass
def run_child(self):
pid = os.fork()
if pid == 0:
signal.signal(signal.SIGHUP, signal.SIG_DFL)
signal.signal(signal.SIGTERM, signal.SIG_DFL)
# ignore the interrupt signal to avoid a race whereby
# a child worker receives the signal before the parent
# and is respawned unneccessarily as a result
signal.signal(signal.SIGINT, signal.SIG_IGN)
self.run_server()
self.logger.info(_('Child %d exiting normally') % os.getpid())
# self.pool.waitall() has been called by run_server, so
# its safe to exit here
sys.exit(0)
else:
self.logger.info(_('Started child %s') % pid)
self.children.append(pid)
def run_server(self):
"""Run a WSGI server."""
eventlet.wsgi.HttpProtocol.default_request_version = "HTTP/1.0"
try:
eventlet.hubs.use_hub('poll')
except Exception:
msg = _("eventlet 'poll' hub is not available on this platform")
raise exception.WorkerCreationFailure(reason=msg)
self.pool = self.create_pool()
try:
eventlet.wsgi.server(self.sock, self.app_func(),
log=WritableLogger(self.logger), custom_pool=self.pool)
except socket.error, err:
if err[0] != errno.EINVAL:
raise
self.pool.waitall()
def _single_run(self, application, sock):
"""Start a WSGI server in a new green thread."""
self.logger.info(_("Starting single process server"))
eventlet.wsgi.server(sock, application, custom_pool=self.pool,
log=WritableLogger(self.logger))
class Middleware(object):
"""
Base WSGI middleware wrapper. These classes require an application to be
initialized that will be called next. By default the middleware will
simply call its wrapped app, or you can override __call__ to customize its
behavior.
"""
def __init__(self, application):
self.application = application
@classmethod
def factory(cls, global_conf, **local_conf):
def filter(app):
return cls(app)
return filter
def process_request(self, req):
"""
Called on each request.
If this returns None, the next application down the stack will be
executed. If it returns a response then that response will be returned
and execution will stop here.
"""
return None
def process_response(self, response):
"""Do whatever you'd like to the response."""
return response
@webob.dec.wsgify
def __call__(self, req):
response = self.process_request(req)
if response:
return response
response = req.get_response(self.application)
return self.process_response(response)
class Debug(Middleware):
"""
Helper class that can be inserted into any WSGI application chain
to get information about the request and response.
"""
@webob.dec.wsgify
def __call__(self, req):
print ("*" * 40) + " REQUEST ENVIRON"
for key, value in req.environ.items():
print key, "=", value
print
resp = req.get_response(self.application)
print ("*" * 40) + " RESPONSE HEADERS"
for (key, value) in resp.headers.iteritems():
print key, "=", value
print
resp.app_iter = self.print_generator(resp.app_iter)
return resp
@staticmethod
def print_generator(app_iter):
"""
Iterator that prints the contents of a wrapper string iterator
when iterated.
"""
print ("*" * 40) + " BODY"
for part in app_iter:
sys.stdout.write(part)
sys.stdout.flush()
yield part
print
class Router(object):
"""
WSGI middleware that maps incoming requests to WSGI apps.
"""
def __init__(self, mapper):
"""
Create a router for the given routes.Mapper.
Each route in `mapper` must specify a 'controller', which is a
WSGI app to call. You'll probably want to specify an 'action' as
well and have your controller be a wsgi.Controller, who will route
the request to the action method.
Examples:
mapper = routes.Mapper()
sc = ServerController()
# Explicit mapping of one route to a controller+action
mapper.connect(None, "/svrlist", controller=sc, action="list")
# Actions are all implicitly defined
mapper.resource("server", "servers", controller=sc)
# Pointing to an arbitrary WSGI app. You can specify the
# {path_info:.*} parameter so the target app can be handed just that
# section of the URL.
mapper.connect(None, "/v1.0/{path_info:.*}", controller=BlogApp())
"""
self.map = mapper
self._router = routes.middleware.RoutesMiddleware(self._dispatch,
self.map)
@classmethod
def factory(cls, global_conf, **local_conf):
return cls(routes.Mapper())
@webob.dec.wsgify
def __call__(self, req):
"""
Route the incoming request to a controller based on self.map.
If no match, return a 404.
"""
return self._router
@staticmethod
@webob.dec.wsgify
def _dispatch(req):
"""
Called by self._router after matching the incoming request to a route
and putting the information into req.environ. Either returns 404
or the routed WSGI app's response.
"""
match = req.environ['wsgiorg.routing_args'][1]
if not match:
return webob.exc.HTTPNotFound()
app = match['controller']
return app
class Request(webob.Request):
"""Add some Openstack API-specific logic to the base webob.Request."""
def best_match_content_type(self):
"""Determine the requested response content-type."""
supported = ('application/json',)
bm = self.accept.best_match(supported)
return bm or 'application/json'
def get_content_type(self, allowed_content_types):
"""Determine content type of the request body."""
if not "Content-Type" in self.headers:
raise exception.InvalidContentType(content_type=None)
content_type = self.content_type
if content_type not in allowed_content_types:
raise exception.InvalidContentType(content_type=content_type)
else:
return content_type
class JSONRequestDeserializer(object):
def has_body(self, request):
"""
Returns whether a Webob.Request object will possess an entity body.
:param request: Webob.Request object
"""
if 'transfer-encoding' in request.headers:
return True
elif request.content_length > 0:
return True
return False
def from_json(self, datastring):
try:
return json.loads(datastring)
except ValueError:
msg = _('Malformed JSON in request body.')
raise webob.exc.HTTPBadRequest(explanation=msg)
def default(self, request):
if self.has_body(request):
return {'body': self.from_json(request.body)}
else:
return {}
class JSONResponseSerializer(object):
def to_json(self, data):
def sanitizer(obj):
if isinstance(obj, datetime.datetime):
return obj.isoformat()
return obj
return json.dumps(data, default=sanitizer)
def default(self, response, result):
response.content_type = 'application/json'
response.body = self.to_json(result)
class Resource(object):
"""
WSGI app that handles (de)serialization and controller dispatch.
Reads routing information supplied by RoutesMiddleware and calls
the requested action method upon its deserializer, controller,
and serializer. Those three objects may implement any of the basic
controller action methods (create, update, show, index, delete)
along with any that may be specified in the api router. A 'default'
method may also be implemented to be used in place of any
non-implemented actions. Deserializer methods must accept a request
argument and return a dictionary. Controller methods must accept a
request argument. Additionally, they must also accept keyword
arguments that represent the keys returned by the Deserializer. They
may raise a webob.exc exception or return a dict, which will be
serialized by requested content type.
"""
def __init__(self, controller, deserializer=None, serializer=None):
"""
:param controller: object that implement methods created by routes lib
:param deserializer: object that supports webob request deserialization
through controller-like actions
:param serializer: object that supports webob response serialization
through controller-like actions
"""
self.controller = controller
self.serializer = serializer or JSONResponseSerializer()
self.deserializer = deserializer or JSONRequestDeserializer()
@webob.dec.wsgify(RequestClass=Request)
def __call__(self, request):
"""WSGI method that controls (de)serialization and method dispatch."""
action_args = self.get_action_args(request.environ)
action = action_args.pop('action', None)
deserialized_request = self.dispatch(self.deserializer,
action, request)
action_args.update(deserialized_request)
action_result = self.dispatch(self.controller, action,
request, **action_args)
try:
response = webob.Response(request=request)
self.dispatch(self.serializer, action, response, action_result)
return response
# return unserializable result (typically a webob exc)
except Exception:
return action_result
def dispatch(self, obj, action, *args, **kwargs):
"""Find action-specific method on self and call it."""
try:
method = getattr(obj, action)
except AttributeError:
method = getattr(obj, 'default')
return method(*args, **kwargs)
def get_action_args(self, request_environment):
"""Parse dictionary created by routes library."""
try:
args = request_environment['wsgiorg.routing_args'][1].copy()
except Exception:
return {}
try:
del args['controller']
except KeyError:
pass
try:
del args['format']
except KeyError:
pass
return args