OpenTracing Shim for OpenTelemetry
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 TracerShim
instance is created and then used as if
it were an “ordinary” OpenTracing 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 float
values, the
OpenTelemetry Python API represents time values as the number of
nanoseconds since the epoch expressed as 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 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
- opentelemetry.shim.opentracing_shim.create_tracer(otel_tracer_provider)[source]
Creates a
TracerShim
object from the provided OpenTelemetryopentelemetry.trace.TracerProvider
.The returned
TracerShim
is an implementation ofopentracing.Tracer
using OpenTelemetry under the hood.- Parameters:
otel_tracer_provider (
TracerProvider
) – A tracer from this provider will be used to perform the actual tracing when user code is instrumented using the OpenTracing API.- Return type:
- Returns:
The created
TracerShim
.
- class opentelemetry.shim.opentracing_shim.SpanContextShim(otel_context)[source]
Implements
opentracing.SpanContext
by wrapping aopentelemetry.trace.SpanContext
object.- Parameters:
otel_context (
SpanContext
) – Aopentelemetry.trace.SpanContext
to be used for constructing theSpanContextShim
.
- unwrap()[source]
Returns the wrapped
opentelemetry.trace.SpanContext
object.- Return type:
- Returns:
The
opentelemetry.trace.SpanContext
object wrapped by thisSpanContextShim
.
- class opentelemetry.shim.opentracing_shim.SpanShim(tracer, context, span)[source]
Wraps a
opentelemetry.trace.Span
object.- Parameters:
tracer – The
opentracing.Tracer
that created this SpanShim.context (
SpanContextShim
) – ASpanContextShim
which contains the context for thisSpanShim
.span – A
opentelemetry.trace.Span
to wrap.
- unwrap()[source]
Returns the wrapped
opentelemetry.trace.Span
object.- Returns:
The
opentelemetry.trace.Span
object wrapped by thisSpanShim
.
- set_operation_name(operation_name)[source]
Updates the name of the wrapped OpenTelemetry span.
- Parameters:
operation_name (
str
) – The new name to be used for the underlyingopentelemetry.trace.Span
object.- Return type:
- Returns:
Returns this
SpanShim
instance to allow call chaining.
- finish(finish_time=None)[source]
Ends the OpenTelemetry span wrapped by this
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.
- Parameters:
finish_time (
Optional
[float
]) – A value that represents the finish time expressed as the number of seconds since the epoch as returned bytime.time()
.
- log_kv(key_values, timestamp=None)[source]
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.- Parameters:
key_values (
Optional
[Mapping
[str
,Union
[str
,bool
,int
,float
,Sequence
[str
],Sequence
[bool
],Sequence
[int
],Sequence
[float
]]]]) – A dictionary as specified inopentelemetry.trace.util.Attributes
.timestamp (
Optional
[float
]) – Timestamp of the OpenTelemetry event, will be generated automatically if omitted.
- Return type:
- Returns:
Returns this
SpanShim
instance to allow call chaining.
- class opentelemetry.shim.opentracing_shim.ScopeShim(manager, span, span_cm=None)[source]
A ScopeShim wraps the OpenTelemetry functionality related to span activation/deactivation while using OpenTracing
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
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
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 usingScopeManagerShim.activate()
.- Parameters:
manager (
ScopeManagerShim
) – TheScopeManagerShim
that created thisScopeShim
.span_cm – A Python context manager which yields an OpenTelemetry opentelemetry.trace.Span from its
__enter__()
method. Used byfrom_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.
- classmethod from_context_manager(manager, span_cm)[source]
Constructs a
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, )
- Parameters:
manager (
ScopeManagerShim
) – TheScopeManagerShim
that created thisScopeShim
.span_cm – A context manager as returned by
opentelemetry.trace.use_span()
.
- close()[source]
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
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 byScopeManagerShim.active()
) always ends the associated span, regardless of the value passed in finish_on_close when activating the span.
- class opentelemetry.shim.opentracing_shim.ScopeManagerShim(tracer)[source]
Implements
opentracing.ScopeManager
by setting and getting the active opentelemetry.trace.Span in the OpenTelemetry tracer.This class keeps a reference to a
TracerShim
as an attribute. This reference is used to communicate with the OpenTelemetry tracer. It is necessary to have a reference to theTracerShim
rather than theopentelemetry.trace.Tracer
wrapped by it because when constructing aSpanShim
we need to pass a reference to aopentracing.Tracer
.- Parameters:
tracer (
TracerShim
) – ATracerShim
to use for setting and getting active span state.
- activate(span, finish_on_close)[source]
Activates a
SpanShim
and returns aScopeShim
which represents the active span.
- property active: ScopeShim
Returns a
ScopeShim
object representing the currently-active span in the OpenTelemetry tracer.- Returns:
A
ScopeShim
representing the active span in the OpenTelemetry tracer, or None if no span is currently active.
Warning
Calling
ScopeShim.close()
on theScopeShim
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.
- property tracer: TracerShim
Returns the
TracerShim
reference used by thisScopeManagerShim
for setting and getting the active span from the OpenTelemetry tracer.- Returns:
The
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.
- class opentelemetry.shim.opentracing_shim.TracerShim(tracer)[source]
Wraps a
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
opentelemetry.trace.Tracer
should work with this class.- Parameters:
tracer (
Tracer
) – Aopentelemetry.trace.Tracer
to use for tracing. This tracer will be invoked by the shim to create actual spans.
- unwrap()[source]
Returns the
opentelemetry.trace.Tracer
object that is wrapped by thisTracerShim
and used for actual tracing.- Returns:
The
opentelemetry.trace.Tracer
used for actual tracing.
- start_active_span(operation_name, child_of=None, references=None, tags=None, start_time=None, ignore_active_span=False, finish_on_close=True)[source]
Starts and activates a span. In terms of functionality, this method behaves exactly like the same method on a “regular” OpenTracing tracer. See
opentracing.Tracer.start_active_span()
for more details.- Parameters:
operation_name (
str
) – Name of the operation represented by the new span from the perspective of the current service.child_of (
Union
[SpanShim
,SpanContextShim
,None
]) – ASpanShim
orSpanContextShim
representing the parent in a “child of” reference. If specified, the references parameter must be omitted.references (
Optional
[list
]) – A list ofopentracing.Reference
objects that identify one or more parents of typeSpanContextShim
.tags (
Optional
[Mapping
[str
,Union
[str
,bool
,int
,float
,Sequence
[str
],Sequence
[bool
],Sequence
[int
],Sequence
[float
]]]]) – A dictionary of tags.start_time (
Optional
[float
]) – An explicit start time expressed as the number of seconds since the epoch as returned bytime.time()
.ignore_active_span (
bool
) – Ignore the currently-active span in the OpenTelemetry tracer and make the created span the root span of a new trace.finish_on_close (
bool
) – Determines whether the created span should end automatically when closing the returnedScopeShim
.
- Return type:
- Returns:
A
ScopeShim
that is already activated by theScopeManagerShim
.
- start_span(operation_name=None, child_of=None, references=None, tags=None, start_time=None, ignore_active_span=False)[source]
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
opentracing.Tracer.start_span()
for more details.- Parameters:
operation_name (
Optional
[str
]) – Name of the operation represented by the new span from the perspective of the current service.child_of (
Union
[SpanShim
,SpanContextShim
,None
]) – ASpanShim
orSpanContextShim
representing the parent in a “child of” reference. If specified, the references parameter must be omitted.references (
Optional
[list
]) – A list ofopentracing.Reference
objects that identify one or more parents of typeSpanContextShim
.tags (
Optional
[Mapping
[str
,Union
[str
,bool
,int
,float
,Sequence
[str
],Sequence
[bool
],Sequence
[int
],Sequence
[float
]]]]) – A dictionary of tags.start_time (
Optional
[float
]) – An explicit start time expressed as the number of seconds since the epoch as returned bytime.time()
.ignore_active_span (
bool
) – Ignore the currently-active span in the OpenTelemetry tracer and make the created span the root span of a new trace.
- Return type:
- Returns:
An already-started
SpanShim
instance.
- inject(span_context, format, carrier)[source]
Injects
span_context
intocarrier
.See base class for more details.