OpenStack Orchestration (Heat)
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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.
# 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
# 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 re
from lxml import etree
import eventlet
import eventlet.greenio
from import socket, ssl
import eventlet.wsgi
from paste import deploy
import routes
import routes.middleware
import webob.dec
import webob.exc
from heat.common import exception
from heat.openstack.common import cfg
from heat.openstack.common import importutils
from heat.openstack.common import utils
bind_opts = [
cfg.StrOpt('bind_host', default=''),
socket_opts = [
cfg.IntOpt('backlog', default=4096),
workers_opt = cfg.IntOpt('workers', default=0)
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(conf, default_port=None):
"""Return the host and port to bind to."""
return (conf.bind_host, conf.bind_port or default_port)
def get_socket(conf, default_port):
Bind socket to bind ip:port in conf
note: Mostly comes from Swift with a few small changes...
:param conf: a cfg.ConfigOpts object
: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(conf, 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"))
sock = None
retry_until = time.time() + 30
while not sock and time.time() < retry_until:
sock = eventlet.listen(bind_addr, backlog=conf.backlog,
if use_ssl:
sock = ssl.wrap_socket(sock, certfile=cert_file,
except socket.error, err:
if err.args[0] != errno.EADDRINUSE:
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, 600)
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, conf, default_port):
Run a WSGI server with the given application.
:param application: The application to run in the WSGI server
:param conf: a cfg.ConfigOpts object
: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 received'))
signal.signal(signal.SIGTERM, 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.application = application
self.sock = get_socket(conf, default_port)
self.logger = logging.getLogger('eventlet.wsgi.server')
if conf.workers == 0:
# Useful for profiling, test, debug etc.
self.pool = eventlet.GreenPool(size=self.threads)
self.pool.spawn_n(self._single_run, application, self.sock)
return"Starting %d workers") % conf.workers)
signal.signal(signal.SIGTERM, kill_children)
signal.signal(signal.SIGHUP, hup)
while len(self.children) < conf.workers:
def wait_on_children(self):
while self.running:
pid, status = os.wait()
if os.WIFEXITED(status) or os.WIFSIGNALED(status):
self.logger.error(_('Removing dead child %s') % pid)
except OSError, err:
if err.errno not in (errno.EINTR, errno.ECHILD):
except KeyboardInterrupt:
sys.exit(1)'Caught keyboard interrupt. Exiting.'))
def wait(self):
"""Wait until all servers have completed running."""
if self.children:
except KeyboardInterrupt:
def run_child(self):
pid = os.fork()
if pid == 0:
signal.signal(signal.SIGHUP, signal.SIG_DFL)
signal.signal(signal.SIGTERM, signal.SIG_DFL)
self.run_server()'Child %d exiting normally') % os.getpid())
else:'Started child %s') % pid)
def run_server(self):
"""Run a WSGI server."""
eventlet.wsgi.HttpProtocol.default_request_version = "HTTP/1.0"
eventlet.patcher.monkey_patch(all=False, socket=True)
self.pool = eventlet.GreenPool(size=self.threads)
eventlet.wsgi.server(self.sock, self.application,
log=WritableLogger(self.logger), custom_pool=self.pool)
except socket.error, err:
if err[0] != errno.EINVAL:
def _single_run(self, application, sock):
"""Start a WSGI server in a new green thread.""""Starting single process server"))
eventlet.wsgi.server(sock, application, custom_pool=self.pool,
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
def __init__(self, application):
self.application = application
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
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.
def __call__(self, req):
print ("*" * 40) + " REQUEST ENVIRON"
for key, value in req.environ.items():
print key, "=", value
resp = req.get_response(self.application)
print ("*" * 40) + " RESPONSE HEADERS"
for (key, value) in resp.headers.iteritems():
print key, "=", value
resp.app_iter = self.print_generator(resp.app_iter)
return resp
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:
yield part
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.
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())
""" = mapper
self._router = routes.middleware.RoutesMiddleware(self._dispatch,
def __call__(self, req):
Route the incoming request to a controller based on
If no match, return a 404.
return self._router
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)
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):
return json.loads(datastring)
def default(self, request):
if self.has_body(request):
return {'body': self.from_json(request.body)}
return {}
class JSONResponseSerializer(object):
def to_json(self, data):
def sanitizer(obj):
if isinstance(obj, datetime.datetime):
return obj.isoformat()
return obj
response = json.dumps(data, default=sanitizer)
logging.debug("JSON response : %s" % response)
return response
def default(self, response, result):
response.content_type = 'application/json'
response.body = self.to_json(result)
# Escape XML serialization for these keys, as the AWS API defines them as
# JSON inside XML when the response format is XML.
JSON_ONLY_KEYS = ('TemplateBody', 'Metadata')
class XMLResponseSerializer(object):
def object_to_element(self, obj, element):
if isinstance(obj, list):
for item in obj:
subelement = etree.SubElement(element, "member")
self.object_to_element(item, subelement)
elif isinstance(obj, dict):
for key, value in obj.items():
subelement = etree.SubElement(element, key)
if key in JSON_ONLY_KEYS:
if value:
subelement.text = str(value)
self.object_to_element(value, subelement)
element.text = str(obj)
def to_xml(self, data):
# Assumption : root node is dict with single key
root = data.keys()[0]
eltree = etree.Element(root)
doc = etree.ElementTree(eltree)
self.object_to_element(data.get(root), eltree)
response = etree.tostring(eltree)
logging.debug("XML response : %s" % response)
return response
def default(self, response, result):
response.content_type = 'application/xml'
response.body = self.to_xml(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, 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.deserializer = deserializer
self.serializer = serializer
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)
# From reading the boto code, and observation of real AWS api responses
# it seems that the AWS api ignores the content-type in the html header
# Instead it looks at a "ContentType" GET query parameter
# This doesn't seem to be documented in the AWS cfn API spec, but it
# would appear that the default response serialization is XML, as
# described in the API docs, but passing a query parameter of
# ContentType=JSON results in a JSON serialized response...
content_type = request.params.get("ContentType")
deserialized_request = self.dispatch(self.deserializer,
action, request)
action_result = self.dispatch(self.controller, action,
request, **action_args)
# Here we support either passing in a serializer or detecting it
# based on the content type.
serializer = self.serializer
if serializer is None:
if content_type == "JSON":
serializer = JSONResponseSerializer()
serializer = XMLResponseSerializer()
response = webob.Response(request=request)
self.dispatch(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."""
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."""
args = request_environment['wsgiorg.routing_args'][1].copy()
except Exception:
return {}
del args['controller']
except KeyError:
del args['format']
except KeyError:
return args
class BasePasteFactory(object):
"""A base class for paste app and filter factories.
Sub-classes must override the KEY class attribute and provide
a __call__ method.
KEY = None
def __init__(self, conf):
self.conf = conf
def __call__(self, global_conf, **local_conf):
raise NotImplementedError
def _import_factory(self, local_conf):
"""Import an app/filter class.
Lookup the KEY from the PasteDeploy local conf and import the
class named there. This class can then be used as an app or
filter factory.
Note we support the <module>:<class> format.
Note also that if you do e.g.
key =
then ConfigParser returns a value with a leading newline, so
we strip() the value before using it.
class_name = local_conf[self.KEY].replace(':', '.').strip()
return importutils.import_class(class_name)
class AppFactory(BasePasteFactory):
"""A Generic paste.deploy app factory.
This requires heat.app_factory to be set to a callable which returns a
WSGI app when invoked. The format of the name is <module>:<callable> e.g.
paste.app_factory = heat.common.wsgi:app_factory
heat.app_factory = heat.api.v1:API
The WSGI app constructor must accept a ConfigOpts object and a local config
dict as its two arguments.
KEY = 'heat.app_factory'
def __call__(self, global_conf, **local_conf):
"""The actual paste.app_factory protocol method."""
factory = self._import_factory(local_conf)
return factory(self.conf, **local_conf)
class FilterFactory(AppFactory):
"""A Generic paste.deploy filter factory.
This requires heat.filter_factory to be set to a callable which returns a
WSGI filter when invoked. The format is <module>:<callable> e.g.
paste.filter_factory = heat.common.wsgi:filter_factory
heat.filter_factory = heat.api.middleware.cache:CacheFilter
The WSGI filter constructor must accept a WSGI app, a ConfigOpts object and
a local config dict as its three arguments.
KEY = 'heat.filter_factory'
def __call__(self, global_conf, **local_conf):
"""The actual paste.filter_factory protocol method."""
factory = self._import_factory(local_conf)
def filter(app):
return factory(app, self.conf, **local_conf)
return filter
def setup_paste_factories(conf):
"""Set up the generic paste app and filter factories.
Set things up so that:
paste.app_factory = heat.common.wsgi:app_factory
paste.filter_factory = heat.common.wsgi:filter_factory
work correctly while loading PasteDeploy configuration.
The app factories are constructed at runtime to allow us to pass a
ConfigOpts object to the WSGI classes.
:param conf: a ConfigOpts object
global app_factory, filter_factory
app_factory = AppFactory(conf)
filter_factory = FilterFactory(conf)
def teardown_paste_factories():
"""Reverse the effect of setup_paste_factories()."""
global app_factory, filter_factory
del app_factory
del filter_factory
def paste_deploy_app(paste_config_file, app_name, conf):
"""Load a WSGI app from a PasteDeploy configuration.
Use deploy.loadapp() to load the app from the PasteDeploy configuration,
ensuring that the supplied ConfigOpts object is passed to the app and
filter constructors.
:param paste_config_file: a PasteDeploy config file
:param app_name: the name of the app/pipeline to load from the file
:param conf: a ConfigOpts object to supply to the app and its filters
:returns: the WSGI app
return deploy.loadapp("config:%s" % paste_config_file, name=app_name)