You can enable Stackdriver Trace for Python applications by using OpenCensus. OpenCensus is a set of instrumentation libraries for collecting trace and metric data that work with multiple backends. For the latest details about OpenCensus for Python, along with additional documentation and examples, go to census-instrumentation/opencensus-python.
Installation and configuration
To collect traces, you need to import the Stackdriver exporter and
the OpenCensus tracer packages. Your application must also instantiate
from opencensus.ext.stackdriver import trace_exporter as stackdriver_exporter import opencensus.trace.tracer def initialize_tracer(project_id): exporter = stackdriver_exporter.StackdriverExporter( project_id=project_id ) tracer = opencensus.trace.tracer.Tracer( exporter=exporter, sampler=opencensus.trace.tracer.samplers.AlwaysOnSampler() ) return tracer
If you are running on GCP infrastructure, then
you don't need to set
project_id to your GCP
project ID. If you don't set this field, the client library for Python
automatically gathers this data from a GCP metadata server.
If you aren't running on GCP infrastructure, then you must supply your GCP project ID to your application.
Regardless of your infrastructure,
when you don't explicitly set the GCP project ID,
google-cloud Python library, which is invoked by OpenCensus,
automatically determines if the environment variable
is set, and if so, the library uses the value of
as your GCP project ID. For more information on authentication
when using client libraries, see Authentication.
For general information, see Getting started with authentication.
To set the environment variable, do the following:
Linux or macOS
To reduce the performance impact of reporting trace data, have this data
sent by a background process. To configure background reporting of trace data,
transport=AsyncTransport when initializing the
Configuring your platform
You can use Trace on GCP and when your application runs outside of GCP.
Running on GCP
When your application is running on GCP, your application is automatically authenticated and you don't need to provide authentication credentials. However, you do need to ensure that your GCP platform has the Stackdriver Trace API access scope enabled.
For the following configurations, the default settings for the access scopes have the Stackdriver Trace API enabled:
- App Engine flexible environment
App Engine standard environment
Google Kubernetes Engine
If you use custom access scopes, then you must ensure that
Stackdriver Trace API access scope
gcloud users, specify access scopes using the
and include the
trace.append Stackdriver Trace API access scope.
For example, to create a GKE cluster with only
the Stackdriver Trace API enabled, do the following:
gcloud container clusters create example-cluster-name --scopes=https://www.googleapis.com/auth/trace.append
Running locally and elsewhere
When your application is running outside of GCP, you must provide authentication credentials in the form of a service account to the client library. The service account must contain the Cloud Trace agent role. For instructions, see Creating a service account.
GCP client libraries use
Application default credentials (ADC) to find your
application's credentials. You provide these credentials
by setting the
GOOGLE_APPLICATION_CREDENTIALS environment variable:
@app.route('/index.html', methods=['GET']) def index(): tracer = app.config['TRACER'] tracer.start_span(name='index') # Add up to 1 sec delay, weighted toward zero time.sleep(random.random() ** 2) result = "Tracing requests" tracer.end_span() return result
Viewing the traces
After deployment, you can view the traces in the GCP Console Trace Viewer.