# 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.
# 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 typing
import urllib.parse
from opentelemetry import baggage
from opentelemetry.context import get_current
from opentelemetry.context.context import Context
from opentelemetry.propagators import textmap
[docs]class W3CBaggagePropagator(textmap.TextMapPropagator):
"""Extracts and injects Baggage which is used to annotate telemetry."""
_MAX_HEADER_LENGTH = 8192
_MAX_PAIR_LENGTH = 4096
_MAX_PAIRS = 180
_BAGGAGE_HEADER_NAME = "baggage"
[docs] def inject(
self,
carrier: textmap.CarrierT,
context: typing.Optional[Context] = None,
setter: textmap.Setter = textmap.default_setter,
) -> None:
"""Injects Baggage into the carrier.
See
`opentelemetry.propagators.textmap.TextMapPropagator.inject`
"""
baggage_entries = baggage.get_all(context=context)
if not baggage_entries:
return
baggage_string = _format_baggage(baggage_entries)
setter.set(carrier, self._BAGGAGE_HEADER_NAME, baggage_string)
@property
def fields(self) -> typing.Set[str]:
"""Returns a set with the fields set in `inject`."""
return {self._BAGGAGE_HEADER_NAME}
def _format_baggage(baggage_entries: typing.Mapping[str, object]) -> str:
return ",".join(
key + "=" + urllib.parse.quote_plus(str(value))
for key, value in baggage_entries.items()
)
def _extract_first_element(
items: typing.Optional[typing.Iterable[textmap.CarrierT]],
) -> typing.Optional[textmap.CarrierT]:
if items is None:
return None
return next(iter(items), None)