OpenTracing API for Python¶

This library is a Python platform API for OpenTracing.

Required Reading¶

In order to understand the Python platform API, one must first be familiar with the OpenTracing project and terminology more specifically.

Status¶

In the current version, opentracing-python provides only the API and a basic no-op implementation that can be used by instrumentation libraries to collect and propagate distributed tracing context.

Future versions will include a reference implementation utilizing an abstract Recorder interface, as well as a Zipkin-compatible Tracer.

Usage¶

The work of instrumentation libraries generally consists of three steps:

When a service receives a new request (over HTTP or some other protocol), it uses OpenTracing’s inject/extract API to continue an active trace, creating a Span object in the process. If the request does not contain an active trace, the service starts a new trace and a new root Span.
The service needs to store the current Span in some request-local storage, (called Span activation) where it can be retrieved from when a child Span must be created, e.g. in case of the service making an RPC to another service.
When making outbound calls to another service, the current Span must be retrieved from request-local storage, a child span must be created (e.g., by using the start_child_span() helper), and that child span must be embedded into the outbound request (e.g., using HTTP headers) via OpenTracing’s inject/extract API.

Below are the code examples for the previously mentioned steps. Implementation of request-local storage needed for step 2 is specific to the service and/or frameworks / instrumentation libraries it is using, exposed as a ScopeManager child contained as Tracer.scope_manager. See details below.

Inbound request¶

Somewhere in your server’s request handler code:

def handle_request(request):
    span = before_request(request, opentracing.tracer)
    # store span in some request-local storage using Tracer.scope_manager,
    # using the returned `Scope` as Context Manager to ensure
    # `Span` will be cleared and (in this case) `Span.finish()` be called.
    with tracer.scope_manager.activate(span, True) as scope:
        # actual business logic
        handle_request_for_real(request)


def before_request(request, tracer):
    span_context = tracer.extract(
        format=Format.HTTP_HEADERS,
        carrier=request.headers,
    )
    span = tracer.start_span(
        operation_name=request.operation,
        child_of(span_context))
    span.set_tag('http.url', request.full_url)

    remote_ip = request.remote_ip
    if remote_ip:
        span.set_tag(tags.PEER_HOST_IPV4, remote_ip)

    caller_name = request.caller_name
    if caller_name:
        span.set_tag(tags.PEER_SERVICE, caller_name)

    remote_port = request.remote_port
    if remote_port:
        span.set_tag(tags.PEER_PORT, remote_port)

    return span

Outbound request¶

Somewhere in your service that’s about to make an outgoing call:

from opentracing.ext import tags
from opentracing.propagation import Format
from opentracing_instrumentation import request_context

# create and serialize a child span and use it as context manager
with before_http_request(
    request=out_request,
    current_span_extractor=request_context.get_current_span):

    # actual call
    return urllib2.urlopen(request)


def before_http_request(request, current_span_extractor):
    op = request.operation
    parent_span = current_span_extractor()
    outbound_span = opentracing.tracer.start_span(
        operation_name=op,
        child_of=parent_span
    )

    outbound_span.set_tag('http.url', request.full_url)
    service_name = request.service_name
    host, port = request.host_port
    if service_name:
        outbound_span.set_tag(tags.PEER_SERVICE, service_name)
    if host:
        outbound_span.set_tag(tags.PEER_HOST_IPV4, host)
    if port:
        outbound_span.set_tag(tags.PEER_PORT, port)

    http_header_carrier = {}
    opentracing.tracer.inject(
        span_context=outbound_span,
        format=Format.HTTP_HEADERS,
        carrier=http_header_carrier)

    for key, value in http_header_carrier.iteritems():
        request.add_header(key, value)

    return outbound_span

Scope and within-process propagation¶

For getting/setting the current active Span in the used request-local storage, OpenTracing requires that every Tracer contains a ScopeManager that grants access to the active Span through a Scope. Any Span may be transferred to another task or thread, but not Scope.

# Access to the active span is straightforward.
scope = tracer.scope_manager.active()
if scope is not None:
    scope.span.set_tag('...', '...')

The common case starts a Scope that’s automatically registered for intra-process propagation via ScopeManager.

Note that start_active_span('...') automatically finishes the span on Scope.close() (start_active_span('...', finish_on_close=False) does not finish it, in contrast).

# Manual activation of the Span.
span = tracer.start_span(operation_name='someWork')
with tracer.scope_manager.activate(span, True) as scope:
    # Do things.

# Automatic activation of the Span.
# finish_on_close is a required parameter.
with tracer.start_active_span('someWork', finish_on_close=True) as scope:
    # Do things.

# Handling done through a try construct:
span = tracer.start_span(operation_name='someWork')
scope = tracer.scope_manager.activate(span, True)
try:
    # Do things.
except Exception as e:
    scope.set_tag('error', '...')
finally:
    scope.finish()

If there is a Scope, it will act as the parent to any newly started Span unless the programmer passes ignore_active_span=True at start_span()/start_active_span() time or specified parent context explicitly:

scope = tracer.start_active_span('someWork', ignore_active_span=True)

Each service/framework ought to provide a specific ScopeManager implementation that relies on their own request-local storage (thread-local storage, or coroutine-based storage for asynchronous frameworks, for example).

Scope managers¶

This project includes a set of ScopeManager implementations under the opentracing.ext.scope_manager submodule, which can be imported on demand:

from opentracing.ext.scope_manager import ThreadLocalScopeManager

There exist implementations for thread-local (the default), gevent, Tornado and asyncio:

from opentracing.ext.scope_manager.gevent import GeventScopeManager # requires gevent
from opentracing.ext.scope_manager.tornado import TornadoScopeManager # requires Tornado
from opentracing.ext.scope_manager.asyncio import AsyncioScopeManager # requires Python 3.4 or newer.

Development¶

Tests¶

virtualenv env
. ./env/bin/activate
make bootstrap
make test

Testbed suite¶

A testbed suite designed to test API changes and experimental features is included under the testbed directory. For more information, see the Testbed README.

Instrumentation Tests¶

This project has a working design of interfaces for the OpenTracing API. There is a MockTracer to facilitate unit-testing of OpenTracing Python instrumentation.

from opentracing.mocktracer import MockTracer

tracer = MockTracer()
with tracer.start_span('someWork') as span:
    pass

spans = tracer.finished_spans()
someWorkSpan = spans[0]

Documentation¶

virtualenv env
. ./env/bin/activate
make bootstrap
make docs

The documentation is written to docs/_build/html.

LICENSE¶

[MIT License](./LICENSE).

Releases¶

Before new release, add a summary of changes since last version to CHANGELOG.rst

pip install zest.releaser[recommended]
prerelease
release
git push origin master --follow-tags
python setup.py sdist upload -r pypi upload_docs -r pypi
postrelease
git push

Python API¶

Classes¶

class opentracing.Span(tracer, context)¶

Span represents a unit of work executed on behalf of a trace. Examples of spans include a remote procedure call, or a in-process method call to a sub-component. Every span in a trace may have zero or more causal parents, and these relationships transitively form a DAG. It is common for spans to have at most one parent, and thus most traces are merely tree structures.

Span implements a context manager API that allows the following usage:

with tracer.start_span(operation_name='go_fishing') as span:
    call_some_service()

In the context manager syntax it’s not necessary to call Span.finish()

context¶

Provides access to the SpanContext associated with this Span.

The SpanContext contains state that propagates from Span to Span in a larger trace.

Return type:	SpanContext
Returns:	the `SpanContext` associated with this `Span`.

finish(finish_time=None)¶

Indicates that the work represented by this Span has completed or terminated.

With the exception of the Span.context property, the semantics of all other Span methods are undefined after Span.finish() has been invoked.

Parameters:	finish_time (float) – an explicit `Span` finish timestamp as a unix timestamp per `time.time()`

get_baggage_item(key)¶

Retrieves value of the baggage item with the given key.

Parameters:	key (str) – key of the baggage item
Return type:	str
Returns:	value of the baggage item with given key, or `None`.

log(**kwargs)¶: DEPRECATED

log_event(event, payload=None)¶: DEPRECATED

log_kv(key_values, timestamp=None)¶

Adds a log record to the Span.

For example:

span.log_kv({
    "event": "time to first byte",
    "packet.size": packet.size()})

span.log_kv({"event": "two minutes ago"}, time.time() - 120)

Parameters:	key_values (dict) – A dict of string keys and values of any type timestamp (float) – A unix timestamp per `time.time()`; current time if `None`
Return type:	Span
Returns:	the `Span` itself, for call chaining.

set_baggage_item(key, value)¶

Stores a Baggage item in the Span as a key/value pair.

Enables powerful distributed context propagation functionality where arbitrary application data can be carried along the full path of request execution throughout the system.

Note 1: Baggage is only propagated to the future (recursive) children of this Span.

Note 2: Baggage is sent in-band with every subsequent local and remote calls, so this feature must be used with care.

Parameters:	key (str) – Baggage item key value (str) – Baggage item value
Return type:	Span
Returns:	itself, for chaining the calls.

set_operation_name(operation_name)¶

Changes the operation name.

Parameters:	operation_name (str) – the new operation name
Return type:	Span
Returns:	the `Span` itself, for call chaining.

set_tag(key, value)¶

Attaches a key/value pair to the Span.

The value must be a string, a bool, or a numeric type.

If the user calls set_tag multiple times for the same key, the behavior of the Tracer is undefined, i.e. it is implementation specific whether the Tracer will retain the first value, or the last value, or pick one randomly, or even keep all of them.

Parameters:	key (str) – key or name of the tag. Must be a string. value (string or bool or int or float) – value of the tag.
Return type:	Span
Returns:	the `Span` itself, for call chaining.

tracer¶

Provides access to the Tracer that created this Span.

Return type:	Tracer
Returns:	the `Tracer` that created this `Span`.

class opentracing.SpanContext¶

SpanContext represents Span state that must propagate to descendant Spans and across process boundaries.

SpanContext is logically divided into two pieces: the user-level “Baggage” (see Span.set_baggage_item() and Span.get_baggage_item()) that propagates across Span boundaries and any tracer-implementation-specific fields that are needed to identify or otherwise contextualize the associated Span (e.g., a (trace_id, span_id, sampled) tuple).

baggage¶

Return baggage associated with this SpanContext. If no baggage has been added to the Span, returns an empty dict.

The caller must not modify the returned dictionary.

Return type:	dict
Returns:	baggage associated with this `SpanContext` or `{}`.

class opentracing.Scope(manager, span)¶

A scope formalizes the activation and deactivation of a Span, usually from a CPU standpoint. Many times a Span will be extant (in that Span.finish() has not been called) despite being in a non-runnable state from a CPU/scheduler standpoint. For instance, a Span representing the client side of an RPC will be unfinished but blocked on IO while the RPC is still outstanding. A scope defines when a given Span is scheduled and on the path.

Parameters:	manager (ScopeManager) – the `ScopeManager` that created this `Scope`. span (Span) – the `Span` used for this `Scope`.

close()¶

Marks the end of the active period for this Scope, updating ScopeManager.active in the process.

NOTE: Calling this method more than once on a single Scope leads to undefined behavior.

manager¶

Returns the ScopeManager that created this Scope.

Return type:	ScopeManager

span¶

Returns the Span wrapped by this Scope.

Return type:	Span

class opentracing.ScopeManager¶

The ScopeManager interface abstracts both the activation of a Span and access to an active Span/Scope.

activate(span, finish_on_close)¶

Makes a Span active.

Parameters:	span – the `Span` that should become active. finish_on_close – whether `Span` should be automatically finished when `Scope.close()` is called.
Return type:	Scope
Returns:	a `Scope` to control the end of the active period for span. It is a programming error to neglect to call `Scope.close()` on the returned instance.

active¶

Returns the currently active Scope which can be used to access the currently active Scope.span.

If there is a non-null Scope, its wrapped Span becomes an implicit parent of any newly-created Span at Tracer.start_active_span() time.

Return type:	Scope
Returns:	the `Scope` that is active, or `None` if not available.

class opentracing.Tracer(scope_manager=None)¶

Tracer is the entry point API between instrumentation code and the tracing implementation.

This implementation both defines the public Tracer API, and provides a default no-op behavior.

active_span¶

Provides access to the the active Span. This is a shorthand for Tracer.scope_manager.active.span, and None will be returned if Scope.span is None.

Return type:	`Span`
Returns:	the active `Span`.

extract(format, carrier)¶

Returns a SpanContext instance extracted from a carrier of the given format, or None if no such SpanContext could be found.

The type of carrier is determined by format. See the Format class/namespace for the built-in OpenTracing formats.

Implementations must raise UnsupportedFormatException if format is unknown or disallowed.

Implementations may raise InvalidCarrierException, SpanContextCorruptedException, or implementation-specific errors if there are problems with carrier.

Parameters:	format – a python object instance that represents a given carrier format. format may be of any type, and format equality is defined by python `==` equality. carrier – the format-specific carrier object to extract from
Return type:	SpanContext
Returns:	a `SpanContext` extracted from carrier or `None` if no such `SpanContext` could be found.

inject(span_context, format, carrier)¶

Injects span_context into carrier.

The type of carrier is determined by format. See the Format class/namespace for the built-in OpenTracing formats.

Implementations must raise UnsupportedFormatException if format is unknown or disallowed.

Parameters:	span_context (SpanContext) – the `SpanContext` instance to inject format (Format) – a python object instance that represents a given carrier format. format may be of any type, and format equality is defined by python `==` equality. carrier – the format-specific carrier object to inject into

scope_manager¶

Provides access to the current ScopeManager.

Return type:	`ScopeManager`

start_active_span(operation_name, child_of=None, references=None, tags=None, start_time=None, ignore_active_span=False, finish_on_close=True)¶

Returns a newly started and activated Scope.

The returned Scope supports with-statement contexts. For example:

with tracer.start_active_span('...') as scope:
    scope.span.set_tag('http.method', 'GET')
    do_some_work()
# Span.finish() is called as part of scope deactivation through
# the with statement.

It’s also possible to not finish the Span when the Scope context expires:

with tracer.start_active_span('...',
                              finish_on_close=False) as scope:
    scope.span.set_tag('http.method', 'GET')
    do_some_work()
# Span.finish() is not called as part of Scope deactivation as
# `finish_on_close` is `False`.

Parameters:	operation_name (str) – name of the operation represented by the new `Span` from the perspective of the current service. child_of (Span or SpanContext) – (optional) a `Span` or `SpanContext` instance representing the parent in a REFERENCE_CHILD_OF reference. If specified, the references parameter must be omitted. references (`list` of `Reference`) – (optional) references that identify one or more parent `SpanContext`s. (See the Reference documentation for detail). tags (dict) – an optional dictionary of `Span` tags. The caller gives up ownership of that dictionary, because the `Tracer` may use it as-is to avoid extra data copying. start_time (float) – an explicit `Span` start time as a unix timestamp per `time.time()`. ignore_active_span (bool) – (optional) an explicit flag that ignores the current active `Scope` and creates a root `Span`. finish_on_close (bool) – whether `Span` should automatically be finished when `Scope.close()` is called.
Return type:	Scope
Returns:	a `Scope`, already registered via the `ScopeManager`.

start_span(operation_name=None, child_of=None, references=None, tags=None, start_time=None, ignore_active_span=False)¶

Starts and returns a new Span representing a unit of work.

Starting a root Span (a Span with no causal references):

tracer.start_span('...')

Starting a child Span (see also start_child_span()):

tracer.start_span(
    '...',
    child_of=parent_span)

Starting a child Span in a more verbose way:

tracer.start_span(
    '...',
    references=[opentracing.child_of(parent_span)])

Parameters:	operation_name (str) – name of the operation represented by the new `Span` from the perspective of the current service. child_of (Span or SpanContext) – (optional) a `Span` or `SpanContext` representing the parent in a REFERENCE_CHILD_OF reference. If specified, the references parameter must be omitted. references (`list` of `Reference`) – (optional) references that identify one or more parent `SpanContext`s. (See the Reference documentation for detail). tags (dict) – an optional dictionary of `Span` tags. The caller gives up ownership of that dictionary, because the `Tracer` may use it as-is to avoid extra data copying. start_time (float) – an explicit Span start time as a unix timestamp per `time.time()` ignore_active_span (bool) – an explicit flag that ignores the current active `Scope` and creates a root `Span`.
Return type:	Span
Returns:	an already-started `Span` instance.

class opentracing.ReferenceType¶

A namespace for OpenTracing reference types.

See http://opentracing.io/spec for more detail about references, reference types, and CHILD_OF and FOLLOWS_FROM in particular.

class opentracing.Reference¶

A Reference pairs a reference type with a referenced SpanContext.

References are used by Tracer.start_span() to describe the relationships between Spans.

Tracer implementations must ignore references where referenced_context is None. This behavior allows for simpler code when an inbound RPC request contains no tracing information and as a result Tracer.extract() returns None:

parent_ref = tracer.extract(opentracing.HTTP_HEADERS, request.headers)
span = tracer.start_span(
    'operation', references=child_of(parent_ref)
)

See child_of() and follows_from() helpers for creating these references.

class opentracing.Format¶

A namespace for builtin carrier formats.

These static constants are intended for use in the Tracer.inject() and Tracer.extract() methods. E.g.:

tracer.inject(span.context, Format.BINARY, binary_carrier)

BINARY = 'binary'¶

The BINARY format represents SpanContexts in an opaque bytearray carrier.

For both Tracer.inject() and Tracer.extract() the carrier should be a bytearray instance. Tracer.inject() must append to the bytearray carrier (rather than replace its contents).

HTTP_HEADERS = 'http_headers'¶

The HTTP_HEADERS format represents SpanContexts in a python dict mapping from character-restricted strings to strings.

Keys and values in the HTTP_HEADERS carrier must be suitable for use as HTTP headers (without modification or further escaping). That is, the keys have a greatly restricted character set, casing for the keys may not be preserved by various intermediaries, and the values should be URL-escaped.

NOTE: The HTTP_HEADERS carrier dict may contain unrelated data (e.g., arbitrary gRPC metadata). As such, the Tracer implementation should use a prefix or other convention to distinguish tracer-specific key:value pairs.

TEXT_MAP = 'text_map'¶

The TEXT_MAP format represents SpanContexts in a python dict mapping from strings to strings.

Both the keys and the values have unrestricted character sets (unlike the HTTP_HEADERS format).

NOTE: The TEXT_MAP carrier dict may contain unrelated data (e.g., arbitrary gRPC metadata). As such, the Tracer implementation should use a prefix or other convention to distinguish tracer-specific key:value pairs.

Utility Functions¶

opentracing.start_child_span(parent_span, operation_name, tags=None, start_time=None)¶

A shorthand method that starts a child_of Span for a given parent Span.

Equivalent to calling:

parent_span.tracer().start_span(
    operation_name,
    references=opentracing.child_of(parent_span.context),
    tags=tags,
    start_time=start_time)

Parameters:	parent_span (Span) – the `Span` which will act as the parent in the returned `Span`s child_of reference. operation_name (str) – the operation name for the child `Span` instance tags (dict) – optional dict of `Span` tags. The caller gives up ownership of that dict, because the `Tracer` may use it as-is to avoid extra data copying. start_time (float) – an explicit `Span` start time as a unix timestamp per `time.time()`.
Return type:	Span
Returns:	an already-started `Span` instance.

opentracing.child_of(referenced_context=None)¶

child_of is a helper that creates CHILD_OF References.

Parameters:	referenced_context (SpanContext) – the (causal parent) `SpanContext` to reference. If `None` is passed, this reference must be ignored by the `Tracer`.
Return type:	Reference
Returns:	A reference suitable for `Tracer.start_span(..., references=...)`

opentracing.follows_from(referenced_context=None)¶

follows_from is a helper that creates FOLLOWS_FROM References.

Parameters:	referenced_context (SpanContext) – the (causal parent) `SpanContext` to reference. If `None` is passed, this reference must be ignored by the `Tracer`.
Return type:	Reference
Returns:	A Reference suitable for `Tracer.start_span(..., references=...)`

Exceptions¶

class opentracing.InvalidCarrierException¶

InvalidCarrierException should be used when the provided carrier instance does not match what the format argument requires.

See Tracer.inject() and Tracer.extract().

class opentracing.SpanContextCorruptedException¶

SpanContextCorruptedException should be used when the underlying SpanContext state is seemingly present but not well-formed.

See Tracer.inject() and Tracer.extract().

class opentracing.UnsupportedFormatException¶

UnsupportedFormatException should be used when the provided format value is unknown or disallowed by the Tracer.

See Tracer.inject() and Tracer.extract().

MockTracer¶

class opentracing.mocktracer.MockTracer(scope_manager=None)¶

MockTracer makes it easy to test the semantics of OpenTracing instrumentation.

By using a MockTracer as a Tracer implementation for tests, a developer can assert that Span properties and relationships with other Spans are defined as expected by instrumentation code.

By default, MockTracer registers propagators for Format.TEXT_MAP, Format.HTTP_HEADERS and Format.BINARY. The user should call register_propagator() for each additional inject/extract format.

extract(format, carrier)¶

Returns a SpanContext instance extracted from a carrier of the given format, or None if no such SpanContext could be found.

The type of carrier is determined by format. See the Format class/namespace for the built-in OpenTracing formats.

Implementations must raise UnsupportedFormatException if format is unknown or disallowed.

Implementations may raise InvalidCarrierException, SpanContextCorruptedException, or implementation-specific errors if there are problems with carrier.

Parameters:	format – a python object instance that represents a given carrier format. format may be of any type, and format equality is defined by python `==` equality. carrier – the format-specific carrier object to extract from
Return type:	SpanContext
Returns:	a `SpanContext` extracted from carrier or `None` if no such `SpanContext` could be found.

finished_spans()¶

Return a copy of all finished Spans started by this MockTracer (since construction or the last call to reset())

Return type:	list
Returns:	a copy of the finished Spans.

inject(span_context, format, carrier)¶

Injects span_context into carrier.

The type of carrier is determined by format. See the Format class/namespace for the built-in OpenTracing formats.

Implementations must raise UnsupportedFormatException if format is unknown or disallowed.

Parameters:	span_context (SpanContext) – the `SpanContext` instance to inject format (Format) – a python object instance that represents a given carrier format. format may be of any type, and format equality is defined by python `==` equality. carrier – the format-specific carrier object to inject into

register_propagator(format, propagator)¶

Register a propagator with this MockTracer.

Parameters:	format (string) – a `Format` identifier like `TEXT_MAP` propagator (Propagator) – a Propagator instance to handle inject/extract calls involving format

reset()¶

Clear the finished Spans queue.

Note that this does not have any effect on Spans created by MockTracer that have not finished yet; those will still be enqueued in finished_spans() when they finish().

start_active_span(operation_name, child_of=None, references=None, tags=None, start_time=None, ignore_active_span=False, finish_on_close=True)¶

Returns a newly started and activated Scope.

The returned Scope supports with-statement contexts. For example:

with tracer.start_active_span('...') as scope:
    scope.span.set_tag('http.method', 'GET')
    do_some_work()
# Span.finish() is called as part of scope deactivation through
# the with statement.

It’s also possible to not finish the Span when the Scope context expires:

with tracer.start_active_span('...',
                              finish_on_close=False) as scope:
    scope.span.set_tag('http.method', 'GET')
    do_some_work()
# Span.finish() is not called as part of Scope deactivation as
# `finish_on_close` is `False`.

Parameters:	operation_name (str) – name of the operation represented by the new `Span` from the perspective of the current service. child_of (Span or SpanContext) – (optional) a `Span` or `SpanContext` instance representing the parent in a REFERENCE_CHILD_OF reference. If specified, the references parameter must be omitted. references (`list` of `Reference`) – (optional) references that identify one or more parent `SpanContext`s. (See the Reference documentation for detail). tags (dict) – an optional dictionary of `Span` tags. The caller gives up ownership of that dictionary, because the `Tracer` may use it as-is to avoid extra data copying. start_time (float) – an explicit `Span` start time as a unix timestamp per `time.time()`. ignore_active_span (bool) – (optional) an explicit flag that ignores the current active `Scope` and creates a root `Span`. finish_on_close (bool) – whether `Span` should automatically be finished when `Scope.close()` is called.
Return type:	Scope
Returns:	a `Scope`, already registered via the `ScopeManager`.

start_span(operation_name=None, child_of=None, references=None, tags=None, start_time=None, ignore_active_span=False)¶

Starts and returns a new Span representing a unit of work.

Starting a root Span (a Span with no causal references):

tracer.start_span('...')

Starting a child Span (see also start_child_span()):

tracer.start_span(
    '...',
    child_of=parent_span)

Starting a child Span in a more verbose way:

tracer.start_span(
    '...',
    references=[opentracing.child_of(parent_span)])

Parameters:	operation_name (str) – name of the operation represented by the new `Span` from the perspective of the current service. child_of (Span or SpanContext) – (optional) a `Span` or `SpanContext` representing the parent in a REFERENCE_CHILD_OF reference. If specified, the references parameter must be omitted. references (`list` of `Reference`) – (optional) references that identify one or more parent `SpanContext`s. (See the Reference documentation for detail). tags (dict) – an optional dictionary of `Span` tags. The caller gives up ownership of that dictionary, because the `Tracer` may use it as-is to avoid extra data copying. start_time (float) – an explicit Span start time as a unix timestamp per `time.time()` ignore_active_span (bool) – an explicit flag that ignores the current active `Scope` and creates a root `Span`.
Return type:	Span
Returns:	an already-started `Span` instance.

Scope managers¶

class opentracing.ext.scope_manager.ThreadLocalScopeManager¶

ScopeManager implementation that stores the current active Scope using thread-local storage.

activate(span, finish_on_close)¶

Make a Span instance active.

Parameters:	span – the `Span` that should become active. finish_on_close – whether span should automatically be finished when `Scope.close()` is called.
Returns:	a `Scope` instance to control the end of the active period for the `Span`. It is a programming error to neglect to call `Scope.close()` on the returned instance.

active¶

Return the currently active Scope which can be used to access the currently active Scope.span.

Returns:	the `Scope` that is active, or `None` if not available.

class opentracing.ext.scope_manager.gevent.GeventScopeManager¶

ScopeManager implementation for gevent that stores the Scope in the current greenlet (gevent.getcurrent()).

Automatic Span propagation from parent greenlets to their children is not provided, which needs to be done manually:

def child_greenlet(span):
    # activate the parent Span, but do not finish it upon
    # deactivation. That will be done by the parent greenlet.
    with tracer.scope_manager.activate(span, finish_on_close=False):
        with tracer.start_active_span('child') as scope:
            ...

def parent_greenlet():
    with tracer.start_active_span('parent') as scope:
        ...
        gevent.spawn(child_greenlet, span).join()
        ...

activate(span, finish_on_close)¶

Make a Span instance active.

Parameters:	span – the `Span` that should become active. finish_on_close – whether span should automatically be finished when `Scope.close()` is called.
Returns:	a `Scope` instance to control the end of the active period for the `Span`. It is a programming error to neglect to call `Scope.close()` on the returned instance.

active¶

Return the currently active Scope which can be used to access the currently active Scope.span.

Returns:	the `Scope` that is active, or `None` if not available.

class opentracing.ext.scope_manager.tornado.TornadoScopeManager¶

ScopeManager implementation for Tornado that stores the Scope using a custom StackContext, falling back to thread-local storage if none was found.

Using it under tracer_stack_context() will also automatically propagate the active Span from parent coroutines to their children:

@tornado.gen.coroutine
def child_coroutine():
    # No need to pass 'parent' and activate it here,
    # as it is automatically propagated.
    with tracer.start_active_span('child') as scope:
        ...

@tornado.gen.coroutine
def parent_coroutine():
    with tracer.start_active_span('parent') as scope:
        ...
        yield child_coroutine()
        ...

with tracer_stack_context():
    loop.add_callback(parent_coroutine)

Note

The current version does not support Span activation in children coroutines when the parent yields over multiple of them, as the context is effectively shared by all, and the active Span state is messed up:

@tornado.gen.coroutine
def coroutine(input):
    # No span should be activated here.
    # The parent Span will remain active, though.
    with tracer.start_span('child', child_of=tracer.active_span):
        ...

@tornado.gen.coroutine
def handle_request_wrapper():
    res1 = corotuine('A')
    res2 = corotuine('B')

    yield [res1, res2]

activate(span, finish_on_close)¶

Make a Span instance active.

Parameters:	span – the `Span` that should become active. finish_on_close – whether span should automatically be finished when `Scope.close()` is called.

If no tracer_stack_context() is detected, thread-local storage will be used to store the Scope. Observe that in this case the active Span will not be automatically propagated to the child corotuines.

Returns:	a `Scope` instance to control the end of the active period for the `Span`. It is a programming error to neglect to call `Scope.close()` on the returned instance.

active¶

Return the currently active Scope which can be used to access the currently active Scope.span.

Returns:	the `Scope` that is active, or `None` if not available.

opentracing.ext.scope_manager.tornado.tracer_stack_context()¶

Create a custom Tornado’s StackContext that allows TornadoScopeManager to store the active Span in the thread-local request context.

Suppose you have a method handle_request(request) in the http server. Instead of calling it directly, use a wrapper:

from opentracing.ext.scope_manager.tornado import tracer_stack_context

@tornado.gen.coroutine
def handle_request_wrapper(request, actual_handler, *args, **kwargs)

    request_wrapper = TornadoRequestWrapper(request=request)
    span = http_server.before_request(request=request_wrapper)

    with tracer_stack_context():
        with tracer.scope_manager.activate(span, True):
            return actual_handler(*args, **kwargs)

Returns:	Return a custom `StackContext` that allows `TornadoScopeManager` to activate and propagate `Span` instances.

class opentracing.ext.scope_manager.asyncio.AsyncioScopeManager¶

ScopeManager implementation for asyncio that stores the Scope in the current Task (Task.current_task()), falling back to thread-local storage if none was being executed.

Automatic Span propagation from parent coroutines to their children is not provided, which needs to be done manually:

async def child_coroutine(span):
    # activate the parent Span, but do not finish it upon
    # deactivation. That will be done by the parent coroutine.
    with tracer.scope_manager.activate(span, finish_on_close=False):
        with tracer.start_active_span('child') as scope:
            ...

async def parent_coroutine():
    with tracer.start_active_span('parent') as scope:
        ...
        await child_coroutine(span)
        ...

activate(span, finish_on_close)¶

Make a Span instance active.

Parameters:	span – the `Span` that should become active. finish_on_close – whether span should automatically be finished when `Scope.close()` is called.

If no Task is being executed, thread-local storage will be used to store the Scope.

Returns:	a `Scope` instance to control the end of the active period for the `Span`. It is a programming error to neglect to call `Scope.close()` on the returned instance.

active¶

Return the currently active Scope which can be used to access the currently active Scope.span.

Returns:	the `Scope` that is active, or `None` if not available.

History¶

2.0.0rc2 (2018-04-09)¶

Implement ScopeManager for in-process propagation.

1.3.0 (2018-01-14)¶

Added sphinx-generated documentation.
Remove ‘futures’ from install_requires (#62)
Add a harness check for unicode keys and vals (#40)
Have the harness try all tag value types (#39)

1.2.2 (2016-10-03)¶

Fix KeyError when checking kwargs for optional values

1.2.1 (2016-09-22)¶

Make Span.log(self, **kwargs) smarter

1.2.0 (2016-09-21)¶

Add Span.log_kv and deprecate older logging methods

1.1.0 (2016-08-06)¶

Move set/get_baggage back to Span; add SpanContext.baggage
Raise exception on unknown format

2.0.0.dev3 (2016-07-26)¶

Support SpanContext

2.0.0.dev1 (2016-07-12)¶

Rename ChildOf/FollowsFrom to child_of/follows_from
Rename span_context to referee in Reference
Document expected behavior when referee=None

2.0.0.dev0 (2016-07-11)¶

Support SpanContext (and real semvers)

1.0rc4 (2016-05-21)¶

Add standard tags per http://opentracing.io/data-semantics/

1.0rc3 (2016-03-22)¶

No changes yet

1.0rc3 (2016-03-22)¶

Move to simpler carrier formats

1.0rc2 (2016-03-11)¶

Remove the Injector/Extractor layer

1.0rc1 (2016-02-24)¶

Upgrade to 1.0 RC specification

0.6.3 (2016-01-16)¶

Rename repository back to opentracing-python

0.6.2 (2016-01-15)¶

Validate chaining of logging calls

0.6.1 (2016-01-09)¶

Fix typo in the attributes API test

0.6.0 (2016-01-09)¶

Change inheritance to match api-go: TraceContextSource extends codecs, Tracer extends TraceContextSource
Create API harness

0.5.2 (2016-01-08)¶

Update README and meta.

0.5.1 (2016-01-08)¶

Prepare for PYPI publishing.

0.5.0 (2016-01-07)¶

Remove debug flag
Allow passing tags to start methods
Add Span.add_tags() method

0.4.2 (2016-01-07)¶

Add SPAN_KIND tag

0.4.0 (2016-01-06)¶

Rename marshal -> encode

0.3.1 (2015-12-30)¶

Fix std context implementation to refer to Trace Attributes instead of metadata

0.3.0 (2015-12-29)¶

Rename trace tags to Trace Attributes. Rename RPC tags to PEER. Add README.

0.2.0 (2015-12-28)¶

Export global tracer variable.

0.1.4 (2015-12-28)¶

Rename RPC_SERVICE tag to make it symmetric

0.1.3 (2015-12-27)¶

Allow repeated keys for span tags; add standard tag names for RPC

0.1.2 (2015-12-27)¶

Move creation of child context to TraceContextSource

0.1.1 (2015-12-27)¶

Add log methods

0.1.0 (2015-12-27)¶

Initial public API