Source code for opentelemetry.propagate

# Copyright The OpenTelemetry Authors
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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API for propagation of context.

The propagators for the
``opentelemetry.propagators.composite.CompositePropagator`` can be defined
via configuration in the ``OTEL_PROPAGATORS`` environment variable. This
variable should be set to a comma-separated string of names of values for the
``opentelemetry_propagator`` entry point. For example, setting
``OTEL_PROPAGATORS`` to ``tracecontext,baggage`` (which is the default value)
would instantiate
``opentelemetry.propagators.composite.CompositePropagator`` with 2
propagators, one of type
and other of type ``opentelemetry.baggage.propagation.W3CBaggagePropagator``.
Notice that these propagator classes are defined as
``opentelemetry_propagator`` entry points in the ``pyproject.toml`` file of


    import flask
    import requests
    from opentelemetry import propagate

    PROPAGATOR = propagate.get_global_textmap()

    def get_header_from_flask_request(request, key):
        return request.headers.get_all(key)

    def set_header_into_requests_request(request: requests.Request,
                                            key: str, value: str):
        request.headers[key] = value

    def example_route():
        context = PROPAGATOR.extract(
        request_to_downstream = requests.Request(
            "GET", ""
        session = requests.Session()

.. _Propagation API Specification:

from logging import getLogger
from os import environ
from typing import Optional

from opentelemetry.context.context import Context
from opentelemetry.environment_variables import OTEL_PROPAGATORS
from opentelemetry.propagators import composite, textmap
from opentelemetry.util._importlib_metadata import entry_points

logger = getLogger(__name__)

[docs]def extract( carrier: textmap.CarrierT, context: Optional[Context] = None, getter: textmap.Getter[textmap.CarrierT] = textmap.default_getter, ) -> Context: """Uses the configured propagator to extract a Context from the carrier. Args: getter: an object which contains a get function that can retrieve zero or more values from the carrier and a keys function that can get all the keys from carrier. carrier: and object which contains values that are used to construct a Context. This object must be paired with an appropriate getter which understands how to extract a value from it. context: an optional Context to use. Defaults to root context if not set. """ return get_global_textmap().extract(carrier, context, getter=getter)
[docs]def inject( carrier: textmap.CarrierT, context: Optional[Context] = None, setter: textmap.Setter[textmap.CarrierT] = textmap.default_setter, ) -> None: """Uses the configured propagator to inject a Context into the carrier. Args: carrier: An object that contains a representation of HTTP headers. Should be paired with setter, which should know how to set header values on the carrier. context: An optional Context to use. Defaults to current context if not set. setter: An optional `Setter` object that can set values on the carrier. """ get_global_textmap().inject(carrier, context=context, setter=setter)
propagators = [] # Single use variable here to hack black and make lint pass environ_propagators = environ.get( OTEL_PROPAGATORS, "tracecontext,baggage", ) for propagator in environ_propagators.split(","): propagator = propagator.strip() try: propagators.append( # type: ignore next( # type: ignore iter( # type: ignore entry_points( # type: ignore group="opentelemetry_propagator", name=propagator, ) ) ).load()() ) except StopIteration: raise ValueError( f"Propagator {propagator} not found. It is either misspelled or not installed." ) except Exception: # pylint: disable=broad-except logger.exception("Failed to load propagator: %s", propagator) raise _HTTP_TEXT_FORMAT = composite.CompositePropagator(propagators) # type: ignore
[docs]def get_global_textmap() -> textmap.TextMapPropagator: return _HTTP_TEXT_FORMAT
[docs]def set_global_textmap( http_text_format: textmap.TextMapPropagator, ) -> None: global _HTTP_TEXT_FORMAT # pylint:disable=global-statement _HTTP_TEXT_FORMAT = http_text_format # type: ignore