Demo Sampling

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Why sampling?

• Reduces network, storage, and processing costs by exporting fewer traces.
• Keeps a representative subset of traces for performance and error analysis.
• Deterministic sampling (based on trace ID) ensures consistent decisions across services that share the same trace context.

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Example: TraceIdRatioBased sampler (10%) + Console exporter

• a TraceIdRatioBased sampler with 10% sampling,
• a BatchSpanProcessor,
• a ConsoleSpanExporter for demo output (with an OTLP exporter commented out if you want to send traces to a collector instead).

from opentelemetry import trace
from opentelemetry.sdk.resources import Resource
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import ConsoleSpanExporter, BatchSpanProcessor
from opentelemetry.sdk.trace.sampling import TraceIdRatioBased
def configure_tracer():
    # Use ConsoleSpanExporter for demo; replace with OTLPSpanExporter to send to a collector:
    exporter = ConsoleSpanExporter()
    # exporter = OTLPSpanExporter(endpoint="http://localhost:4318/v1/traces")

    span_processor = BatchSpanProcessor(exporter)
    resource = Resource.create({
        "service.name": "charge-service",
        "service.version": "0.5.0"
    })

    # TraceIdRatioBased accepts a float between 0.0 and 1.0.
    # e.g., 0.1 means roughly 10% of traces will be sampled.
    sampler = TraceIdRatioBased(0.1)

    provider = TracerProvider(resource=resource, sampler=sampler)
    provider.add_span_processor(span_processor)

    # Make this provider the global tracer provider
    trace.set_tracer_provider(provider)

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How to use this in your app

1. Call configure_tracer() during application startup (before handling incoming requests).
2. Run your service (for example, a Flask app exposing a /charge endpoint).
3. Generate requests (e.g., with curl) and watch application stdout for exported spans when requests are sampled.

curl http://127.0.0.1:5000/charge
Charging Users Bank Account

curl http://127.0.0.1:5000/charge
Charging Users Bank Account

curl http://127.0.0.1:5000/charge
Charging Users Bank Account

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Sampler options at a glance

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Resource example

• Example resource used above: { "service.name": "charge-service", "service.version": "0.5.0" }

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Best practices & troubleshooting

• Use a conservative sampling ratio in production to control telemetry costs; consider higher sampling for error traces or slow requests.
• If you require guaranteed capture of specific requests (e.g., errors), implement custom sampling logic or use a tail-based sampling approach at the collector.
• If you switch to OTLP, verify your collector/backend is reachable and the endpoint is correctly configured.
• Monitor the rate of sampled traces and adjust the ratio if you need more or fewer traces.

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Links and references

• Console exporter docs: https://opentelemetry-python.readthedocs.io/en/stable/
• OTLP exporter docs: https://opentelemetry-python.readthedocs.io/en/stable/exporter/otlp/
• OTLP protocol: https://opentelemetry.io/docs/reference/specification/protocol/otlp/
• Flask: https://flask.palletsprojects.com/