trace.py

# Copyright 2017, OpenCensus Authors
#
# 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.

import logging

import requests
import wrapt

from opencensus.trace import (
    attributes_helper,
    exceptions_status,
    execution_context,
    integrations,
)
from opencensus.trace import span as span_module
from opencensus.trace import utils

try:
    from urllib.parse import urlparse
except ImportError:
    from urlparse import urlparse


log = logging.getLogger(__name__)

MODULE_NAME = 'requests'

HTTP_HOST = attributes_helper.COMMON_ATTRIBUTES['HTTP_HOST']
HTTP_METHOD = attributes_helper.COMMON_ATTRIBUTES['HTTP_METHOD']
HTTP_PATH = attributes_helper.COMMON_ATTRIBUTES['HTTP_PATH']
HTTP_ROUTE = attributes_helper.COMMON_ATTRIBUTES['HTTP_ROUTE']
HTTP_STATUS_CODE = attributes_helper.COMMON_ATTRIBUTES['HTTP_STATUS_CODE']
HTTP_URL = attributes_helper.COMMON_ATTRIBUTES['HTTP_URL']


def trace_integration(tracer=None):
    """Wrap the requests library to trace it."""
    log.info('Integrated module: {}'.format(MODULE_NAME))

    if tracer is not None:
        # The execution_context tracer should never be None - if it has not
        # been set it returns a no-op tracer. Most code in this library does
        # not handle None being used in the execution context.
        execution_context.set_opencensus_tracer(tracer)

    # Wrap Session class
    # Since
    # https://github.com/psf/requests/commit/d72d1162142d1bf8b1b5711c664fbbd674f349d1
    # (v0.7.0, Oct 23, 2011), get, post, etc are implemented via request which
    # again, is implemented via Session.request (`Session` was named `session`
    # before v1.0.0, Dec 17, 2012, see
    # https://github.com/psf/requests/commit/4e5c4a6ab7bb0195dececdd19bb8505b872fe120)
    wrapt.wrap_function_wrapper(
        MODULE_NAME, 'Session.request', wrap_session_request)
    # pylint: disable=protected-access
    integrations.add_integration(integrations._Integrations.REQUESTS)


def wrap_session_request(wrapped, instance, args, kwargs):
    """Wrap the session function to trace it."""
    # Check if request was sent from an exporter. If so, do not wrap.
    if execution_context.is_exporter():
        return wrapped(*args, **kwargs)

    method = kwargs.get('method') or args[0]
    url = kwargs.get('url') or args[1]

    excludelist_hostnames = execution_context.get_opencensus_attr(
        'excludelist_hostnames')
    parsed_url = urlparse(url)
    if parsed_url.port is None:
        dest_url = parsed_url.hostname
    else:
        dest_url = '{}:{}'.format(parsed_url.hostname, parsed_url.port)
    if utils.disable_tracing_hostname(dest_url, excludelist_hostnames):
        return wrapped(*args, **kwargs)

    path = parsed_url.path if parsed_url.path else '/'

    _tracer = execution_context.get_opencensus_tracer()
    _span = _tracer.start_span()

    _span.name = '{}'.format(path)
    _span.span_kind = span_module.SpanKind.CLIENT

    try:
        tracer_headers = _tracer.propagator.to_headers(
            _tracer.span_context)
        kwargs.setdefault('headers', {}).update(
            tracer_headers)
    except Exception:  # pragma: NO COVER
        pass

    # Add the component type to attributes
    _tracer.add_attribute_to_current_span(
        "component", "HTTP")

    # Add the requests host to attributes
    _tracer.add_attribute_to_current_span(
        HTTP_HOST, dest_url)

    # Add the requests method to attributes
    _tracer.add_attribute_to_current_span(
        HTTP_METHOD, method.upper())

    # Add the requests path to attributes
    _tracer.add_attribute_to_current_span(
        HTTP_PATH, path)

    # Add the requests url to attributes
    _tracer.add_attribute_to_current_span(HTTP_URL, url)

    try:
        result = wrapped(*args, **kwargs)
    except requests.Timeout:
        _span.set_status(exceptions_status.TIMEOUT)
        raise
    except requests.URLRequired:
        _span.set_status(exceptions_status.INVALID_URL)
        raise
    except Exception as e:
        _span.set_status(exceptions_status.unknown(e))
        raise
    else:
        # Add the status code to attributes
        _tracer.add_attribute_to_current_span(
            HTTP_STATUS_CODE, result.status_code
        )
        _span.set_status(
            utils.status_from_http_code(result.status_code)
        )
        return result
    finally:
        _tracer.end_span()