Files
2020-04-08 10:39:44 -07:00

117 lines
4.1 KiB
Python

import sys
from ddtrace.ext import SpanTypes, http as httpx
from ddtrace.http import store_request_headers, store_response_headers
from ddtrace.propagation.http import HTTPPropagator
from ...compat import iteritems
from ...constants import ANALYTICS_SAMPLE_RATE_KEY
from ...settings import config
class TraceMiddleware(object):
def __init__(self, tracer, service='falcon', distributed_tracing=True):
# store tracing references
self.tracer = tracer
self.service = service
self._distributed_tracing = distributed_tracing
def process_request(self, req, resp):
if self._distributed_tracing:
# Falcon uppercases all header names.
headers = dict((k.lower(), v) for k, v in iteritems(req.headers))
propagator = HTTPPropagator()
context = propagator.extract(headers)
# Only activate the new context if there was a trace id extracted
if context.trace_id:
self.tracer.context_provider.activate(context)
span = self.tracer.trace(
'falcon.request',
service=self.service,
span_type=SpanTypes.WEB,
)
# set analytics sample rate with global config enabled
span.set_tag(
ANALYTICS_SAMPLE_RATE_KEY,
config.falcon.get_analytics_sample_rate(use_global_config=True)
)
span.set_tag(httpx.METHOD, req.method)
span.set_tag(httpx.URL, req.url)
if config.falcon.trace_query_string:
span.set_tag(httpx.QUERY_STRING, req.query_string)
# Note: any request header set after this line will not be stored in the span
store_request_headers(req.headers, span, config.falcon)
def process_resource(self, req, resp, resource, params):
span = self.tracer.current_span()
if not span:
return # unexpected
span.resource = '%s %s' % (req.method, _name(resource))
def process_response(self, req, resp, resource, req_succeeded=None):
# req_succeded is not a kwarg in the API, but we need that to support
# Falcon 1.0 that doesn't provide this argument
span = self.tracer.current_span()
if not span:
return # unexpected
status = httpx.normalize_status_code(resp.status)
# Note: any response header set after this line will not be stored in the span
store_response_headers(resp._headers, span, config.falcon)
# FIXME[matt] falcon does not map errors or unmatched routes
# to proper status codes, so we we have to try to infer them
# here. See https://github.com/falconry/falcon/issues/606
if resource is None:
status = '404'
span.resource = '%s 404' % req.method
span.set_tag(httpx.STATUS_CODE, status)
span.finish()
return
err_type = sys.exc_info()[0]
if err_type is not None:
if req_succeeded is None:
# backward-compatibility with Falcon 1.0; any version
# greater than 1.0 has req_succeded in [True, False]
# TODO[manu]: drop the support at some point
status = _detect_and_set_status_error(err_type, span)
elif req_succeeded is False:
# Falcon 1.1+ provides that argument that is set to False
# if get an Exception (404 is still an exception)
status = _detect_and_set_status_error(err_type, span)
span.set_tag(httpx.STATUS_CODE, status)
# Emit span hook for this response
# DEV: Emit before closing so they can overwrite `span.resource` if they want
config.falcon.hooks._emit('request', span, req, resp)
# Close the span
span.finish()
def _is_404(err_type):
return 'HTTPNotFound' in err_type.__name__
def _detect_and_set_status_error(err_type, span):
"""Detect the HTTP status code from the current stacktrace and
set the traceback to the given Span
"""
if not _is_404(err_type):
span.set_traceback()
return '500'
elif _is_404(err_type):
return '404'
def _name(r):
return '%s.%s' % (r.__module__, r.__class__.__name__)