Source code for opentelemetry.shim.opentracing_shim

# 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.

"""
The OpenTelemetry OpenTracing shim is a library which allows an easy migration
from OpenTracing to OpenTelemetry.

The shim consists of a set of classes which implement the OpenTracing Python
API while using OpenTelemetry constructs behind the scenes. Its purpose is to
allow applications which are already instrumented using OpenTracing to start
using OpenTelemetry with a minimal effort, without having to rewrite large
portions of the codebase.

To use the shim, a :class:`TracerShim` instance is created and then used as if
it were an "ordinary" OpenTracing :class:`opentracing.Tracer`, as in the
following example::

    import time

    from opentelemetry import trace
    from opentelemetry.sdk.trace import TracerProvider
    from opentelemetry.shim.opentracing_shim import create_tracer

    # Define which OpenTelemetry Tracer provider implementation to use.
    trace.set_tracer_provider(TracerProvider())

    # Create an OpenTelemetry Tracer.
    otel_tracer = trace.get_tracer(__name__)

    # Create an OpenTracing shim.
    shim = create_tracer(otel_tracer)

    with shim.start_active_span("ProcessHTTPRequest"):
        print("Processing HTTP request")
        # Sleeping to mock real work.
        time.sleep(0.1)
        with shim.start_active_span("GetDataFromDB"):
            print("Getting data from DB")
            # Sleeping to mock real work.
            time.sleep(0.2)

Note:
    While the OpenTracing Python API represents time values as the number of
    **seconds** since the epoch expressed as :obj:`float` values, the
    OpenTelemetry Python API represents time values as the number of
    **nanoseconds** since the epoch expressed as :obj:`int` values. This fact
    requires the OpenTracing shim to convert time values back and forth between
    the two representations, which involves floating point arithmetic.

    Due to the way computers represent floating point values in hardware,
    representation of decimal floating point values in binary-based hardware is
    imprecise by definition.

    The above results in **slight imprecisions** in time values passed to the
    shim via the OpenTracing API when comparing the value passed to the shim
    and the value stored in the OpenTelemetry :class:`opentelemetry.trace.Span`
    object behind the scenes. **This is not a bug in this library or in
    Python**. Rather, this is a generic problem which stems from the fact that
    not every decimal floating point number can be correctly represented in
    binary, and therefore affects other libraries and programming languages as
    well. More information about this problem can be found in the
    `Floating Point Arithmetic\\: Issues and Limitations`_ section of the
    Python documentation.

    While testing this library, the aforementioned imprecisions were observed
    to be of *less than a microsecond*.

API
---
.. _Floating Point Arithmetic\\: Issues and Limitations:
    https://docs.python.org/3/tutorial/floatingpoint.html
"""

# TODO: make pylint use 3p opentracing module for type inference
# pylint:disable=no-member

import logging
from types import TracebackType
from typing import Optional, Type, TypeVar, Union

from deprecated import deprecated
from opentracing import (
    Format,
    Scope,
    ScopeManager,
    Span,
    SpanContext,
    Tracer,
    UnsupportedFormatException,
)

from opentelemetry.baggage import get_baggage, set_baggage
from opentelemetry.context import Context, attach, detach, get_value, set_value
from opentelemetry.propagate import get_global_textmap
from opentelemetry.shim.opentracing_shim import util
from opentelemetry.shim.opentracing_shim.version import __version__
from opentelemetry.trace import INVALID_SPAN_CONTEXT, Link, NonRecordingSpan
from opentelemetry.trace import SpanContext as OtelSpanContext
from opentelemetry.trace import Tracer as OtelTracer
from opentelemetry.trace import (
    TracerProvider,
    get_current_span,
    set_span_in_context,
    use_span,
)
from opentelemetry.util.types import Attributes

ValueT = TypeVar("ValueT", int, float, bool, str)
logger = logging.getLogger(__name__)


[docs]def create_tracer(otel_tracer_provider: TracerProvider) -> "TracerShim": """Creates a :class:`TracerShim` object from the provided OpenTelemetry :class:`opentelemetry.trace.TracerProvider`. The returned :class:`TracerShim` is an implementation of :class:`opentracing.Tracer` using OpenTelemetry under the hood. Args: otel_tracer_provider: A tracer from this provider will be used to perform the actual tracing when user code is instrumented using the OpenTracing API. Returns: The created :class:`TracerShim`. """ return TracerShim(otel_tracer_provider.get_tracer(__name__, __version__))
[docs]class SpanContextShim(SpanContext): """Implements :class:`opentracing.SpanContext` by wrapping a :class:`opentelemetry.trace.SpanContext` object. Args: otel_context: A :class:`opentelemetry.trace.SpanContext` to be used for constructing the :class:`SpanContextShim`. """ def __init__(self, otel_context: OtelSpanContext): self._otel_context = otel_context # Context is being used here since it must be immutable. self._baggage = Context()
[docs] def unwrap(self) -> OtelSpanContext: """Returns the wrapped :class:`opentelemetry.trace.SpanContext` object. Returns: The :class:`opentelemetry.trace.SpanContext` object wrapped by this :class:`SpanContextShim`. """ return self._otel_context
@property def baggage(self) -> Context: """Returns the ``baggage`` associated with this object""" return self._baggage
[docs]class SpanShim(Span): """Wraps a :class:`opentelemetry.trace.Span` object. Args: tracer: The :class:`opentracing.Tracer` that created this `SpanShim`. context: A :class:`SpanContextShim` which contains the context for this :class:`SpanShim`. span: A :class:`opentelemetry.trace.Span` to wrap. """ def __init__(self, tracer, context: SpanContextShim, span): super().__init__(tracer, context) self._otel_span = span
[docs] def unwrap(self): """Returns the wrapped :class:`opentelemetry.trace.Span` object. Returns: The :class:`opentelemetry.trace.Span` object wrapped by this :class:`SpanShim`. """ return self._otel_span
[docs] def set_operation_name(self, operation_name: str) -> "SpanShim": """Updates the name of the wrapped OpenTelemetry span. Args: operation_name: The new name to be used for the underlying :class:`opentelemetry.trace.Span` object. Returns: Returns this :class:`SpanShim` instance to allow call chaining. """ self._otel_span.update_name(operation_name) return self
[docs] def finish(self, finish_time: float = None): """Ends the OpenTelemetry span wrapped by this :class:`SpanShim`. If *finish_time* is provided, the time value is converted to the OpenTelemetry time format (number of nanoseconds since the epoch, expressed as an integer) and passed on to the OpenTelemetry tracer when ending the OpenTelemetry span. If *finish_time* isn't provided, it is up to the OpenTelemetry tracer implementation to generate a timestamp when ending the span. Args: finish_time: A value that represents the finish time expressed as the number of seconds since the epoch as returned by :func:`time.time()`. """ end_time = finish_time if end_time is not None: end_time = util.time_seconds_to_ns(finish_time) self._otel_span.end(end_time=end_time)
[docs] def set_tag(self, key: str, value: ValueT) -> "SpanShim": """Sets an OpenTelemetry attribute on the wrapped OpenTelemetry span. Args: key: A tag key. value: A tag value. Returns: Returns this :class:`SpanShim` instance to allow call chaining. """ self._otel_span.set_attribute(key, value) return self
[docs] def log_kv( self, key_values: Attributes, timestamp: float = None ) -> "SpanShim": """Logs an event for the wrapped OpenTelemetry span. Note: The OpenTracing API defines the values of *key_values* to be of any type. However, the OpenTelemetry API requires that the values be any one of the types defined in ``opentelemetry.trace.util.Attributes`` therefore, only these types are supported as values. Args: key_values: A dictionary as specified in ``opentelemetry.trace.util.Attributes``. timestamp: Timestamp of the OpenTelemetry event, will be generated automatically if omitted. Returns: Returns this :class:`SpanShim` instance to allow call chaining. """ if timestamp is not None: event_timestamp = util.time_seconds_to_ns(timestamp) else: event_timestamp = None event_name = util.event_name_from_kv(key_values) self._otel_span.add_event(event_name, key_values, event_timestamp) return self
[docs] @deprecated(reason="This method is deprecated in favor of log_kv") def log(self, **kwargs): super().log(**kwargs)
[docs] @deprecated(reason="This method is deprecated in favor of log_kv") def log_event(self, event, payload=None): super().log_event(event, payload=payload)
[docs] def set_baggage_item(self, key: str, value: str): """Stores a Baggage item in the span as a key/value pair. Args: key: A tag key. value: A tag value. """ # pylint: disable=protected-access self._context._baggage = set_baggage( key, value, context=self._context._baggage )
[docs] def get_baggage_item(self, key: str) -> Optional[object]: """Retrieves value of the baggage item with the given key. Args: key: A tag key. Returns: Returns this :class:`SpanShim` instance to allow call chaining. """ # pylint: disable=protected-access return get_baggage(key, context=self._context._baggage)
[docs]class ScopeShim(Scope): """A `ScopeShim` wraps the OpenTelemetry functionality related to span activation/deactivation while using OpenTracing :class:`opentracing.Scope` objects for presentation. Unlike other classes in this package, the `ScopeShim` class doesn't wrap an OpenTelemetry class because OpenTelemetry doesn't have the notion of "scope" (though it *does* have similar functionality). There are two ways to construct a `ScopeShim` object: using the default initializer and using the :meth:`from_context_manager()` class method. It is necessary to have both ways for constructing `ScopeShim` objects because in some cases we need to create the object from an OpenTelemetry `opentelemetry.trace.Span` context manager (as returned by :meth:`opentelemetry.trace.use_span`), in which case our only way of retrieving a `opentelemetry.trace.Span` object is by calling the ``__enter__()`` method on the context manager, which makes the span active in the OpenTelemetry tracer; whereas in other cases we need to accept a `SpanShim` object and wrap it in a `ScopeShim`. The former is used mainly when the instrumentation code retrieves the currently-active span using `ScopeManagerShim.active`. The latter is mainly used when the instrumentation code activates a span using :meth:`ScopeManagerShim.activate`. Args: manager: The :class:`ScopeManagerShim` that created this :class:`ScopeShim`. span: The :class:`SpanShim` this :class:`ScopeShim` controls. span_cm: A Python context manager which yields an OpenTelemetry `opentelemetry.trace.Span` from its ``__enter__()`` method. Used by :meth:`from_context_manager` to store the context manager as an attribute so that it can later be closed by calling its ``__exit__()`` method. Defaults to `None`. """ def __init__( self, manager: "ScopeManagerShim", span: SpanShim, span_cm=None ): super().__init__(manager, span) self._span_cm = span_cm self._token = attach(set_value("scope_shim", self)) # TODO: Change type of `manager` argument to `opentracing.ScopeManager`? We # need to get rid of `manager.tracer` for this.
[docs] @classmethod def from_context_manager(cls, manager: "ScopeManagerShim", span_cm): """Constructs a :class:`ScopeShim` from an OpenTelemetry `opentelemetry.trace.Span` context manager. The method extracts a `opentelemetry.trace.Span` object from the context manager by calling the context manager's ``__enter__()`` method. This causes the span to start in the OpenTelemetry tracer. Example usage:: span = otel_tracer.start_span("TestSpan") span_cm = opentelemetry.trace.use_span(span) scope_shim = ScopeShim.from_context_manager( scope_manager_shim, span_cm=span_cm, ) Args: manager: The :class:`ScopeManagerShim` that created this :class:`ScopeShim`. span_cm: A context manager as returned by :meth:`opentelemetry.trace.use_span`. """ otel_span = span_cm.__enter__() span_context = SpanContextShim(otel_span.get_span_context()) span = SpanShim(manager.tracer, span_context, otel_span) return cls(manager, span, span_cm)
[docs] def close(self): """Closes the `ScopeShim`. If the `ScopeShim` was created from a context manager, calling this method sets the active span in the OpenTelemetry tracer back to the span which was active before this `ScopeShim` was created. In addition, if the span represented by this `ScopeShim` was activated with the *finish_on_close* argument set to `True`, calling this method will end the span. Warning: In the current state of the implementation it is possible to create a `ScopeShim` directly from a `SpanShim`, that is - without using :meth:`from_context_manager()`. For that reason we need to be able to end the span represented by the `ScopeShim` in this case, too. Please note that closing a `ScopeShim` created this way (for example as returned by :meth:`ScopeManagerShim.active`) **always ends the associated span**, regardless of the value passed in *finish_on_close* when activating the span. """ self._end_span_scope(None, None, None)
def __exit__(self, exc_type, exc_val, exc_tb): """ Override the __exit__ method of `opentracing.scope.Scope` so we can report exceptions correctly in opentelemetry specification format. """ self._end_span_scope(exc_type, exc_val, exc_tb) def _end_span_scope( self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType], ) -> None: detach(self._token) if self._span_cm is not None: self._span_cm.__exit__(exc_type, exc_val, exc_tb) else: self._span.unwrap().end()
[docs]class ScopeManagerShim(ScopeManager): """Implements :class:`opentracing.ScopeManager` by setting and getting the active `opentelemetry.trace.Span` in the OpenTelemetry tracer. This class keeps a reference to a :class:`TracerShim` as an attribute. This reference is used to communicate with the OpenTelemetry tracer. It is necessary to have a reference to the :class:`TracerShim` rather than the :class:`opentelemetry.trace.Tracer` wrapped by it because when constructing a :class:`SpanShim` we need to pass a reference to a :class:`opentracing.Tracer`. Args: tracer: A :class:`TracerShim` to use for setting and getting active span state. """ def __init__(self, tracer: "TracerShim"): # The only thing the ``__init__()``` method on the base class does is # initialize `self._noop_span` and `self._noop_scope` with no-op # objects. Therefore, it doesn't seem useful to call it. # pylint: disable=super-init-not-called self._tracer = tracer
[docs] def activate(self, span: SpanShim, finish_on_close: bool) -> "ScopeShim": """Activates a :class:`SpanShim` and returns a :class:`ScopeShim` which represents the active span. Args: span: A :class:`SpanShim` to be activated. finish_on_close(:obj:`bool`): Determines whether the OpenTelemetry span should be ended when the returned :class:`ScopeShim` is closed. Returns: A :class:`ScopeShim` representing the activated span. """ span_cm = use_span(span.unwrap(), end_on_exit=finish_on_close) return ScopeShim.from_context_manager(self, span_cm=span_cm)
@property def active(self) -> "ScopeShim": """Returns a :class:`ScopeShim` object representing the currently-active span in the OpenTelemetry tracer. Returns: A :class:`ScopeShim` representing the active span in the OpenTelemetry tracer, or `None` if no span is currently active. Warning: Calling :meth:`ScopeShim.close` on the :class:`ScopeShim` returned by this property **always ends the corresponding span**, regardless of the *finish_on_close* value used when activating the span. This is a limitation of the current implementation of the OpenTracing shim and is likely to be handled in future versions. """ span = get_current_span() if span.get_span_context() == INVALID_SPAN_CONTEXT: return None try: return get_value("scope_shim") except KeyError: span_context = SpanContextShim(span.get_span_context()) wrapped_span = SpanShim(self._tracer, span_context, span) return ScopeShim(self, span=wrapped_span) @property def tracer(self) -> "TracerShim": """Returns the :class:`TracerShim` reference used by this :class:`ScopeManagerShim` for setting and getting the active span from the OpenTelemetry tracer. Returns: The :class:`TracerShim` used for setting and getting the active span. Warning: This property is *not* a part of the OpenTracing API. It is used internally by the current implementation of the OpenTracing shim and will likely be removed in future versions. """ return self._tracer
[docs]class TracerShim(Tracer): """Wraps a :class:`opentelemetry.trace.Tracer` object. This wrapper class allows using an OpenTelemetry tracer as if it were an OpenTracing tracer. It exposes the same methods as an "ordinary" OpenTracing tracer, and uses OpenTelemetry transparently for performing the actual tracing. This class depends on the *OpenTelemetry API*. Therefore, any implementation of a :class:`opentelemetry.trace.Tracer` should work with this class. Args: tracer: A :class:`opentelemetry.trace.Tracer` to use for tracing. This tracer will be invoked by the shim to create actual spans. """ def __init__(self, tracer: OtelTracer): super().__init__(scope_manager=ScopeManagerShim(self)) self._otel_tracer = tracer self._supported_formats = ( Format.TEXT_MAP, Format.HTTP_HEADERS, )
[docs] def unwrap(self): """Returns the :class:`opentelemetry.trace.Tracer` object that is wrapped by this :class:`TracerShim` and used for actual tracing. Returns: The :class:`opentelemetry.trace.Tracer` used for actual tracing. """ return self._otel_tracer
[docs] def start_active_span( self, operation_name: str, child_of: Union[SpanShim, SpanContextShim] = None, references: list = None, tags: Attributes = None, start_time: float = None, ignore_active_span: bool = False, finish_on_close: bool = True, ) -> "ScopeShim": """Starts and activates a span. In terms of functionality, this method behaves exactly like the same method on a "regular" OpenTracing tracer. See :meth:`opentracing.Tracer.start_active_span` for more details. Args: operation_name: Name of the operation represented by the new span from the perspective of the current service. child_of: A :class:`SpanShim` or :class:`SpanContextShim` representing the parent in a "child of" reference. If specified, the *references* parameter must be omitted. references: A list of :class:`opentracing.Reference` objects that identify one or more parents of type :class:`SpanContextShim`. tags: A dictionary of tags. start_time: An explicit start time expressed as the number of seconds since the epoch as returned by :func:`time.time()`. ignore_active_span: Ignore the currently-active span in the OpenTelemetry tracer and make the created span the root span of a new trace. finish_on_close: Determines whether the created span should end automatically when closing the returned :class:`ScopeShim`. Returns: A :class:`ScopeShim` that is already activated by the :class:`ScopeManagerShim`. """ current_span = get_current_span() if child_of is None and current_span is not INVALID_SPAN_CONTEXT: child_of = SpanShim(None, None, current_span) span = self.start_span( operation_name=operation_name, child_of=child_of, references=references, tags=tags, start_time=start_time, ignore_active_span=ignore_active_span, ) return self._scope_manager.activate(span, finish_on_close)
[docs] def start_span( self, operation_name: str = None, child_of: Union[SpanShim, SpanContextShim] = None, references: list = None, tags: Attributes = None, start_time: float = None, ignore_active_span: bool = False, ) -> SpanShim: """Implements the ``start_span()`` method from the base class. Starts a span. In terms of functionality, this method behaves exactly like the same method on a "regular" OpenTracing tracer. See :meth:`opentracing.Tracer.start_span` for more details. Args: operation_name: Name of the operation represented by the new span from the perspective of the current service. child_of: A :class:`SpanShim` or :class:`SpanContextShim` representing the parent in a "child of" reference. If specified, the *references* parameter must be omitted. references: A list of :class:`opentracing.Reference` objects that identify one or more parents of type :class:`SpanContextShim`. tags: A dictionary of tags. start_time: An explicit start time expressed as the number of seconds since the epoch as returned by :func:`time.time()`. ignore_active_span: Ignore the currently-active span in the OpenTelemetry tracer and make the created span the root span of a new trace. Returns: An already-started :class:`SpanShim` instance. """ # Use active span as parent when no explicit parent is specified. if not ignore_active_span and not child_of: child_of = self.active_span # Use the specified parent or the active span if possible. Otherwise, # use a `None` parent, which triggers the creation of a new trace. parent = child_of.unwrap() if child_of else None if isinstance(parent, OtelSpanContext): parent = NonRecordingSpan(parent) parent_span_context = set_span_in_context(parent) links = [] if references: for ref in references: links.append(Link(ref.referenced_context.unwrap())) # The OpenTracing API expects time values to be `float` values which # represent the number of seconds since the epoch. OpenTelemetry # represents time values as nanoseconds since the epoch. start_time_ns = start_time if start_time_ns is not None: start_time_ns = util.time_seconds_to_ns(start_time) span = self._otel_tracer.start_span( operation_name, context=parent_span_context, links=links, attributes=tags, start_time=start_time_ns, ) context = SpanContextShim(span.get_span_context()) return SpanShim(self, context, span)
[docs] def inject(self, span_context, format: object, carrier: object): """Injects ``span_context`` into ``carrier``. See base class for more details. Args: span_context: The ``opentracing.SpanContext`` to inject. format: a Python object instance that represents a given carrier format. `format` may be of any type, and `format` equality is defined by Python ``==`` operator. carrier: the format-specific carrier object to inject into """ # pylint: disable=redefined-builtin # This implementation does not perform the injecting by itself but # uses the configured propagators in opentelemetry.propagators. # TODO: Support Format.BINARY once it is supported in # opentelemetry-python. if format not in self._supported_formats: raise UnsupportedFormatException propagator = get_global_textmap() span = span_context.unwrap() if span_context else None if isinstance(span, OtelSpanContext): span = NonRecordingSpan(span) ctx = set_span_in_context(span) propagator.inject(carrier, context=ctx)
[docs] def extract(self, format: object, carrier: object): """Returns an ``opentracing.SpanContext`` instance extracted from a ``carrier``. See base class for more details. Args: format: a Python object instance that represents a given carrier format. ``format`` may be of any type, and ``format`` equality is defined by python ``==`` operator. carrier: the format-specific carrier object to extract from Returns: An ``opentracing.SpanContext`` extracted from ``carrier`` or ``None`` if no such ``SpanContext`` could be found. """ # pylint: disable=redefined-builtin # This implementation does not perform the extracing by itself but # uses the configured propagators in opentelemetry.propagators. # TODO: Support Format.BINARY once it is supported in # opentelemetry-python. if format not in self._supported_formats: raise UnsupportedFormatException propagator = get_global_textmap() ctx = propagator.extract(carrier) span = get_current_span(ctx) if span is not None: otel_context = span.get_span_context() else: otel_context = INVALID_SPAN_CONTEXT return SpanContextShim(otel_context)