OpenCensus - A stats collection and distributed tracing framework
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OpenCensus
_ for Python. OpenCensus provides a framework to measure a
server's resource usage and collect performance stats. This repository
contains Python related utilities and supporting software needed by
OpenCensus.
.. _OpenCensus: https://github.com/census-instrumentation
.. _API Documentation: https://opencensus.io/api/python/trace/usage.html
Tracing
Installation & basic usage
-
Install the opencensus package using pip
_ or pipenv
_:
::
pip install opencensus
pipenv install opencensus
-
Initialize a tracer for your application:
.. code:: python
from opencensus.trace.tracer import Tracer
from opencensus.trace.samplers import AlwaysOnSampler
tracer = Tracer(sampler=AlwaysOnSampler())
.. _pip: https://pip.pypa.io
.. _pipenv: https://docs.pipenv.org/
-
Initialize a view_manager and a stats_recorder for your application:
.. code:: python
from opencensus.stats import stats as stats_module
stats = stats_module.stats
view_manager = stats.view_manager
stats_recorder = stats.stats_recorder
Usage
You can collect traces using the Tracer
context manager
_:
.. code:: python
from opencensus.trace.tracer import Tracer
from opencensus.trace.samplers import AlwaysOnSampler
# Initialize a tracer, by default using the `PrintExporter`
tracer = Tracer(sampler=AlwaysOnSampler())
# Example for creating nested spans
with tracer.span(name='span1'):
do_something_to_trace()
with tracer.span(name='span1_child1'):
do_something_to_trace()
with tracer.span(name='span1_child2'):
do_something_to_trace()
with tracer.span(name='span2'):
do_something_to_trace()
OpenCensus will collect everything within the with
statement as a single span.
Alternatively, you can explicitly start and end a span:
.. code:: python
from opencensus.trace.tracer import Tracer
from opencensus.trace.samplers import AlwaysOnSampler
# Initialize a tracer, by default using the `PrintExporter`
tracer = Tracer(sampler=AlwaysOnSampler())
tracer.start_span(name='span1')
do_something_to_trace()
tracer.end_span()
.. _context manager: https://docs.python.org/3/reference/datamodel.html#context-managers
Customization
There are several things you can customize in OpenCensus:
-
Excludelist, which excludes certain hosts and paths from being tracked.
By default, the health check path for the App Engine flexible environment is
not tracked, you can turn it on by excluding it from the excludelist setting.
-
Exporter, which sends the traces.
By default, the traces are printed to stdout in JSON format. You can choose
different exporters to send the traces to. There are three built-in exporters,
which are PrintExporter
, FileExporter
and LoggingExporter
, the
other exporters are provided as extensions <#trace-exporter>
__.
-
Sampler, which determines how traces are sampled.
The default sampler is the ProbabilitySampler
, which samples (i.e.
enables tracing for) a percentage of all requests. Sampling is deterministic
according to the trace ID. To force sampling for all requests, or to prevent
any request from being sampled, see AlwaysOnSampler
and
AlwaysOffSampler
.
-
Propagator, which serializes and deserializes the
SpanContext
and its headers. The default propagator is
TraceContextPropagator
, other propagators include
BinaryFormatPropagator
, GoogleCloudFormatPropagator
and
TextFormatPropagator
.
You can customize while initializing a tracer.
.. code:: python
import requests
from opencensus.trace import config_integration
from opencensus.trace import file_exporter
from opencensus.trace import tracer as tracer_module
from opencensus.trace.propagation import google_cloud_format
from opencensus.trace.samplers import ProbabilitySampler
config_integration.trace_integrations(['httplib'])
tracer = tracer_module.Tracer(
exporter=file_exporter.FileExporter(file_name='traces'),
propagator=google_cloud_format.GoogleCloudFormatPropagator(),
sampler=ProbabilitySampler(rate=0.5),
)
with tracer.span(name='parent'):
with tracer.span(name='child'):
response = requests.get('http://localhost:5000')
You can use a configuration file for Flask/Django/Pyramid. For more
information, please read the
individual integration documentation <#integration>
_.
.. code:: python
'OPENCENSUS': {
'TRACE': {
'EXCLUDELIST_HOSTNAMES': ['localhost', '127.0.0.1'],
'EXCLUDELIST_PATHS': ['_ah/health'],
'SAMPLER': 'opencensus.trace.samplers.ProbabilitySampler(rate=1)',
'EXPORTER': '''opencensus.ext.ocagent.trace_exporter.TraceExporter(
service_name='foobar',
)''',
'PROPAGATOR': 'opencensus.trace.propagation.google_cloud_format.GoogleCloudFormatPropagator()',
}
}
Extensions
Integration
OpenCensus supports integration with popular web frameworks, client libraries and built-in libraries.
Django
_Flask
_gevent
_Google Cloud Client Libraries
_gRPC
_httplib
_httpx
_logging
_MySQL
_PostgreSQL
_pymongo
_PyMySQL
_Pyramid
_requests
_SQLAlchemy
_threading
_
Log Exporter
Metrics Exporter
Stats Exporter
OCAgent
_Prometheus
_Stackdriver
_
Trace Exporter
Azure
_Datadog
_Jaeger
_OCAgent
_Stackdriver
_Zipkin
_
.. _Azure: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-azure
.. _Datadog: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-datadog
.. _Django: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-django
.. _Flask: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-flask
.. _FastAPI: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-fastapi
.. _gevent: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-gevent
.. _Google Cloud Client Libraries: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-google-cloud-clientlibs
.. _gRPC: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-grpc
.. _httplib: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-httplib
.. _httpx: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-httpx
.. _Jaeger: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-jaeger
.. _logging: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-logging
.. _MySQL: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-mysql
.. _OCAgent: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-ocagent
.. _PostgreSQL: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-postgresql
.. _Prometheus: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-prometheus
.. _pymongo: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-pymongo
.. _PyMySQL: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-pymysql
.. _Pyramid: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-pyramid
.. _requests: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-requests
.. _SQLAlchemy: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-sqlalchemy
.. _Stackdriver: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-stackdriver
.. _threading: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-threading
.. _Zipkin: https://github.com/census-instrumentation/opencensus-python/tree/master/contrib/opencensus-ext-zipkin
Versioning
This library follows Semantic Versioning
_.
GA: Libraries defined at a GA quality level are stable, and will not introduce
backwards-incompatible changes in any minor or patch releases. We will address issues and requests
with the highest priority. If we were to make a backwards-incompatible changes on an API, we will
first mark the existing API as deprecated and keep it for 18 months before removing it.
Beta: Libraries defined at a Beta quality level are expected to be mostly stable and we're
working towards their release candidate. We will address issues and requests with a higher priority.
There may be backwards incompatible changes in a minor version release, though not in a patch
release. If an element is part of an API that is only meant to be used by exporters or other
opencensus libraries, then there is no deprecation period. Otherwise, we will deprecate it for 18
months before removing it, if possible.
.. _Semantic Versioning: https://semver.org/