Integrate on Google Cloud Functions Python

The dynatrace-opentelemetry-gcf package provides APIs for tracing Python Google Cloud Functions (GCF).

Prerequisites

Ensure that you have followed the initial configuration steps described in Set up OpenTelemetry monitoring for Google Cloud Functions before using the packages below.

dynatrace-opentelemetry-gcf version 1.247+
Cloud Functions product version: 1st gen, 2nd gen

Installation

To set up OpenTelemetry Python integration on Google Cloud Functions, add the following line to the requirements.txt file of your function:

plaintext
dynatrace-opentelemetry-gcf

This adds the latest version of the dynatrace-opentelemetry-gcf package as a dependency to your function. For more information about managing dependencies, consult the GCF documentation for Python.

Trace export

To export traces to Dynatrace, you need to initialize tracing and then instrument your handler function.

Initialize tracing

Select one of the following ways to initialize tracing:

configure_dynatrace function—This is the recommended option unless you need to manually set up tracing components.

Example with `configure_dynatrace` (recommended)

python
from opentelemetry.sdk.resources import Resource
from opentelemetry.semconv.resource import ResourceAttributes

from dynatrace.opentelemetry.tracing.api import configure_dynatrace

tracer_provider = configure_dynatrace(
  resource=Resource.create({ResourceAttributes.SERVICE_NAME: "My Service"})
)

Manual tracing setup—This allows for a more fine-grained setup of tracing components.

Example with manual tracing setup

python
from opentelemetry.propagate import set_global_textmap
from opentelemetry.sdk.resources import Resource
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.semconv.resource import ResourceAttributes
from opentelemetry.trace import set_tracer_provider

from dynatrace.opentelemetry.tracing.api import (
    DtSampler,
    DtSpanProcessor,
    DtTextMapPropagator,
)

span_processor = DtSpanProcessor()

tracer_provider = TracerProvider(
    sampler=DtSampler(),
    resource=Resource.create({ResourceAttributes.SERVICE_NAME: "My Service"}),
)
tracer_provider.add_span_processor(span_processor)

set_global_textmap(DtTextMapPropagator())
set_tracer_provider(tracer_provider)

The tracing setup code should be implemented to set up tracing only once before any other third-party module is imported. If you use isort to sort your imports, we suggest that you deactivate it while importing the tracing setup module, as shown in the following example:

python
# isort: off
import setup_tracing  # import the module containing your setup code
# isort: on

# import other modules

Instrument a handler function

Use the wrap_handler decorator to instrument your handler function as shown in the following example:

python
import flask

from dynatrace.opentelemetry.gcf import wrap_handler

@wrap_handler
def handler(request: flask.Request) -> flask.Response:
    # From here the created span is available in the OpenTelemetry context as the current span.

    # do something ...
    return flask.Response("Hello World", 200)

Cold start

When the wrapped handler is invoked for the first time after cold start, the decorator will make additional HTTP requests to fetch metadata from your Google Cloud Platform environment. This metadata is used to set the required attributes for Dynatrace to process the span.

Span flush

By default, the wrap_handler decorator automatically performs a flush operation when the decorated function exits to ensure that spans are exported properly. However, flushing spans results in longer execution time, because this operation becomes part of the function's execution logic.

By providing an additional parameter to the decorator, @wrap_handler(flush_on_exit=False), you can disable the flushing after every invocation. Spans will still be periodically exported in the background.

Because code running outside the function execution can be terminated at any time, it's discouraged by Google Cloud Functions.

Google Cloud Functions 1st gen

Background task execution after function invocation is not guaranteed without flushing spans and might result in span loss. In practice, samples have shown that not explicitly flushing spans usually still results in correctly exported spans.
Google Cloud Functions 2nd gen

Google Cloud Functions 2nd gen can handle multiple concurrent requests in a single function instance. The flush operation of one invocation can prolong the execution time of another function invocation. Because function instances usually need to be kept idle for some time to handle multiple concurrent requests, you can disable the flushing of spans to improve performance. For details, see Instance lifecycle. Note that idle function instances are not guaranteed to be allocated CPU unless their CPU allocation mode is set to CPU always allocated.

For details, see Function execution timeline.

Dynatrace overhead

Because span export and metadata fetch take some time during cold starts, they increase the duration of the function and subsequently increase costs.
Pay attention to infrequently invoked functions (usually with cold starts), which might require more time for the TCP handshake during span export.
Any network problem between the exporter and Dynatrace backend might also lead to unexpectedly high overhead.

Limitations

DtSpanProcessor only works together with DtSampler. Make sure to set DtSampler as a sampler when manually setting up tracing; spans might not be exported otherwise.