placement/placement/requestlog.py
Chris Dent 7327f2eeec Merge request log and request id middlewares
This is done to ensure that both are in the outermost
piece of middleware so that we generate and log the
global request id (if any) as early as possible, and
use it, and the local request id, throughout the entire
middleware stack.

This turned out to be somewhat more complex than desired
because:

* The request id middleware from oslo_middleware is a webob
  wsgi app, so we need to map the request log middleware to
  that style (meaning more changes than strictly necessary).

* The __call__ in the request id middleware is not composed
  to make calling it as a super clean, so instead of doing that
  we are copying code. Which implies some risks for which we
  may wish to consider workarounds.

This is an alternative to I5a80056dd88836a4e79a649fa02d36dc7e75eee4

Change-Id: I7e24b54bfcd296f13ea4f65dbb10ba63679c05b1
2019-08-28 09:50:42 +01:00

121 lines
4.4 KiB
Python

# 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.
"""Simple middleware for request logging that also sets request id.
We combine these two pieces of functionality in one middleware because we want
to be sure that we have a DEBUG log at the very start of the request, with a
a global request id, and an INFO log at the very end of the request.
"""
from oslo_context import context
from oslo_log import log as logging
from oslo_middleware import request_id
import webob.dec
from placement import microversion
LOG = logging.getLogger(__name__)
class RequestLog(request_id.RequestId):
"""WSGI Middleware to write a simple request log with a global request id.
Borrowed from Paste Translogger and incorporating
oslo_middleware.request_id.RequestId.
This also guards against a missing "Accept" header.
"""
format = ('%(REMOTE_ADDR)s "%(REQUEST_METHOD)s %(REQUEST_URI)s" '
'status: %(status)s len: %(bytes)s '
'microversion: %(microversion)s')
def __init__(self, application):
self.application = application
@webob.dec.wsgify
def __call__(self, req):
# This duplicates code from __call__ on RequestId, but because of the
# way that method is structured, calling super is not workable.
self.set_global_req_id(req)
# We must instantiate a Request context, otherwise the LOG in the
# next line will not produce the expected output where we would expect
# to see request ids. Instead we get '[-]'. Presumably there be magic
# here...
ctx = context.RequestContext.from_environ(req.environ)
req.environ[request_id.ENV_REQUEST_ID] = ctx.request_id
LOG.debug('Starting request: %s "%s %s"',
req.remote_addr, req.method,
self._get_uri(req.environ))
# Set the accept header if it is not otherwise set or is '*/*'. This
# ensures that error responses will be in JSON.
accept = req.environ.get('HTTP_ACCEPT')
if not accept or accept == '*/*':
req.environ['HTTP_ACCEPT'] = 'application/json'
if LOG.isEnabledFor(logging.INFO):
response = req.get_response(self._log_app)
else:
response = req.get_response(self.application)
return_headers = [request_id.HTTP_RESP_HEADER_REQUEST_ID]
return_headers.extend(self.compat_headers)
for header in return_headers:
if header not in response.headers:
response.headers.add(header, ctx.request_id)
return response
@staticmethod
def _get_uri(environ):
req_uri = (environ.get('SCRIPT_NAME', '') +
environ.get('PATH_INFO', ''))
if environ.get('QUERY_STRING'):
req_uri += '?' + environ['QUERY_STRING']
return req_uri
def _log_app(self, environ, start_response):
req_uri = self._get_uri(environ)
def replacement_start_response(status, headers, exc_info=None):
"""We need to gaze at the content-length, if set, to
write log info.
"""
size = None
for name, value in headers:
if name.lower() == 'content-length':
size = value
self.write_log(environ, req_uri, status, size)
return start_response(status, headers, exc_info)
return self.application(environ, replacement_start_response)
def write_log(self, environ, req_uri, status, size):
"""Write the log info out in a formatted form to ``LOG.info``.
"""
if size is None:
size = '-'
log_format = {
'REMOTE_ADDR': environ.get('REMOTE_ADDR', '-'),
'REQUEST_METHOD': environ['REQUEST_METHOD'],
'REQUEST_URI': req_uri,
'status': status.split(None, 1)[0],
'bytes': size,
'microversion': environ.get(
microversion.MICROVERSION_ENVIRON, '-'),
}
LOG.info(self.format, log_format)