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Python FastAPI Uvicorn

Prerequisites

Python 3

Installation

  1. Install dependencies:

    pip install opentelemetry-distro opentelemetry-exporter-otlp-proto-http opentelemetry-instrumentation-fastapi opentelemetry-instrumentation-system-metrics 
    opentelemetry-bootstrap -a install
  2. Create a file tracing.py in your project directory, with the following content:

    tracing.py
     import os
    from opentelemetry import trace
    from opentelemetry.sdk import resources
    from opentelemetry.sdk.trace import TracerProvider
    from opentelemetry.sdk.trace.export import (
    BatchSpanProcessor,
    ConsoleSpanExporter,
    SimpleSpanProcessor,
    )
    from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
    from opentelemetry import metrics
    from opentelemetry.sdk.metrics import MeterProvider
    from opentelemetry.sdk.metrics.export import (
    ConsoleMetricExporter,
    PeriodicExportingMetricReader,
    )
    from opentelemetry.exporter.otlp.proto.http.metric_exporter import OTLPMetricExporter
    from opentelemetry.instrumentation.system_metrics import SystemMetricsInstrumentor
    from socket import gethostname


    def init_tracing():
    resource = resources.Resource.create({
    resources.HOST_NAME: gethostname() or 'UNSET',
    })

    if os.getenv('OTEL_LOG_LEVEL', '') == 'debug':
    trace_processor = SimpleSpanProcessor(ConsoleSpanExporter())
    else:
    trace_processor = BatchSpanProcessor(OTLPSpanExporter())
    trace_provider = TracerProvider(
    resource=resource,
    active_span_processor=trace_processor
    )
    trace.set_tracer_provider(trace_provider)

    if os.getenv('OTEL_LOG_LEVEL', '') == 'debug':
    metric_exporter = ConsoleMetricExporter()
    else:
    metric_exporter = OTLPMetricExporter()
    metric_reader = PeriodicExportingMetricReader(exporter=metric_exporter)
    meter_provider = MeterProvider(
    resource=resource,
    metric_readers=[metric_reader]
    )
    metrics.set_meter_provider(meter_provider)
    SystemMetricsInstrumentor().instrument()

  3. Add the highlighted lines below to your project's main file:

    main.py
    from fastapi import FastAPI
    from tracing import init_tracing
    from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor

    app = FastAPI()

    init_tracing()
    FastAPIInstrumentor.instrument_app(app)
    # Additional instrumentations can be enabled by
    # following the docs for respective instrumentations at
    # https://github.com/open-telemetry/opentelemetry-python-contrib/tree/main/instrumentation
    #
    # A working example with multiple instrumentations is available at
    # https://github.com/cubeapm/sample_app_python_fastapi_uvicorn/tree/otel

    @app.route('/roll/<number>')
    def roll(number):
    return number
  4. Modify the application run command as follows:

    OTEL_LOGS_EXPORTER=none \
    OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=http://<ip_address_of_cubeapm_server>:4318/v1/traces \
    OTEL_EXPORTER_OTLP_METRICS_ENDPOINT=http://<ip_address_of_cubeapm_server>:3130/api/metrics/v1/save/otlp \
    OTEL_EXPORTER_OTLP_COMPRESSION=gzip \
    OTEL_SERVICE_NAME=<app_name> \
    uvicorn main:app --host=0.0.0.0 --port=8000 --workers=4

Sample Application

A working example is available at https://github.com/cubeapm/sample_app_python_fastapi_uvicorn/tree/otel.

Troubleshooting

The following can be used for debugging:

OTEL_LOG_LEVEL=debug

The following command can be tried on the application host server to check connectivity to CubeAPM server(s):

telnet <ip_address_of_cubeapm_server> 4318