codekingpro/portable-devtools

1# Copyright The OpenTelemetry Authors2#3# Licensed under the Apache License, Version 2.0 (the "License");4# you may not use this file except in compliance with the License.5# You may obtain a copy of the License at6#7#     http://www.apache.org/licenses/LICENSE-2.08#9# Unless required by applicable law or agreed to in writing, software10# distributed under the License is distributed on an "AS IS" BASIS,11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.12# See the License for the specific language governing permissions and13# limitations under the License.14 15"""16API for propagation of context.17 18The propagators for the19``opentelemetry.propagators.composite.CompositePropagator`` can be defined20via configuration in the ``OTEL_PROPAGATORS`` environment variable. This21variable should be set to a comma-separated string of names of values for the22``opentelemetry_propagator`` entry point. For example, setting23``OTEL_PROPAGATORS`` to ``tracecontext,baggage`` (which is the default value)24would instantiate25``opentelemetry.propagators.composite.CompositePropagator`` with 226propagators, one of type27``opentelemetry.trace.propagation.tracecontext.TraceContextTextMapPropagator``28and other of type ``opentelemetry.baggage.propagation.W3CBaggagePropagator``.29Notice that these propagator classes are defined as30``opentelemetry_propagator`` entry points in the ``pyproject.toml`` file of31``opentelemetry``.32 33Example::34 35    import flask36    import requests37    from opentelemetry import propagate38 39 40    PROPAGATOR = propagate.get_global_textmap()41 42 43    def get_header_from_flask_request(request, key):44        return request.headers.get_all(key)45 46    def set_header_into_requests_request(request: requests.Request,47                                            key: str, value: str):48        request.headers[key] = value49 50    def example_route():51        context = PROPAGATOR.extract(52            get_header_from_flask_request,53            flask.request54        )55        request_to_downstream = requests.Request(56            "GET", "http://httpbin.org/get"57        )58        PROPAGATOR.inject(59            set_header_into_requests_request,60            request_to_downstream,61            context=context62        )63        session = requests.Session()64        session.send(request_to_downstream.prepare())65 66 67.. _Propagation API Specification:68    https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/context/api-propagators.md69"""70 71from logging import getLogger72from os import environ73from typing import List, Optional74 75from opentelemetry.context.context import Context76from opentelemetry.environment_variables import OTEL_PROPAGATORS77from opentelemetry.propagators import composite, textmap78from opentelemetry.util._importlib_metadata import entry_points79 80logger = getLogger(__name__)81 82 83def extract(84    carrier: textmap.CarrierT,85    context: Optional[Context] = None,86    getter: textmap.Getter[textmap.CarrierT] = textmap.default_getter,87) -> Context:88    """Uses the configured propagator to extract a Context from the carrier.89 90    Args:91        getter: an object which contains a get function that can retrieve zero92            or more values from the carrier and a keys function that can get all the keys93            from carrier.94        carrier: and object which contains values that are95            used to construct a Context. This object96            must be paired with an appropriate getter97            which understands how to extract a value from it.98        context: an optional Context to use. Defaults to root99            context if not set.100    """101    return get_global_textmap().extract(carrier, context, getter=getter)102 103 104def inject(105    carrier: textmap.CarrierT,106    context: Optional[Context] = None,107    setter: textmap.Setter[textmap.CarrierT] = textmap.default_setter,108) -> None:109    """Uses the configured propagator to inject a Context into the carrier.110 111    Args:112        carrier: the medium used by Propagators to read113            values from and write values to.114            Should be paired with setter, which115            should know how to set header values on the carrier.116        context: An optional Context to use. Defaults to current117            context if not set.118        setter: An optional `Setter` object that can set values119            on the carrier.120    """121    get_global_textmap().inject(carrier, context=context, setter=setter)122 123 124propagators: List[textmap.TextMapPropagator] = []125 126# Single use variable here to hack black and make lint pass127environ_propagators = environ.get(128    OTEL_PROPAGATORS,129    "tracecontext,baggage",130)131 132 133for propagator in environ_propagators.split(","):134    propagator = propagator.strip()135    if propagator.lower() == "none":136        logger.debug(137            "OTEL_PROPAGATORS environment variable contains none, removing all propagators"138        )139        propagators = []140        break141    try:142        propagators.append(143            next(  # type: ignore144                iter(  # type: ignore145                    entry_points(  # type: ignore[misc]146                        group="opentelemetry_propagator",147                        name=propagator,148                    )149                )150            ).load()()151        )152    except StopIteration:153        raise ValueError(154            f"Propagator {propagator} not found. It is either misspelled or not installed."155        )156    except Exception:  # pylint: disable=broad-exception-caught157        logger.exception("Failed to load propagator: %s", propagator)158        raise159 160 161_HTTP_TEXT_FORMAT: textmap.TextMapPropagator = composite.CompositePropagator(162    propagators163)164 165 166def get_global_textmap() -> textmap.TextMapPropagator:167    return _HTTP_TEXT_FORMAT168 169 170def set_global_textmap(171    http_text_format: textmap.TextMapPropagator,172) -> None:173    global _HTTP_TEXT_FORMAT  # pylint:disable=global-statement174    _HTTP_TEXT_FORMAT = http_text_format175