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Setup OpenTelemetry POC

Source https://github.com/vllm-project/vllm/tree/main/examples/online_serving/opentelemetry.

  1. Install OpenTelemetry packages:

    pip install \
  'opentelemetry-sdk>=1.26.0,<1.27.0' \
  'opentelemetry-api>=1.26.0,<1.27.0' \
  'opentelemetry-exporter-otlp>=1.26.0,<1.27.0' \
  'opentelemetry-semantic-conventions-ai>=0.4.1,<0.5.0'

  2. Start Jaeger in a docker container:

    # From: https://www.jaegertracing.io/docs/1.57/getting-started/
docker run --rm --name jaeger \
    -e COLLECTOR_ZIPKIN_HOST_PORT=:9411 \
    -p 6831:6831/udp \
    -p 6832:6832/udp \
    -p 5778:5778 \
    -p 16686:16686 \
    -p 4317:4317 \
    -p 4318:4318 \
    -p 14250:14250 \
    -p 14268:14268 \
    -p 14269:14269 \
    -p 9411:9411 \
    jaegertracing/all-in-one:1.57

  3. In a new shell, export Jaeger IP:

    export JAEGER_IP=$(docker inspect   --format '{{ .NetworkSettings.IPAddress }}' jaeger)
export OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=grpc://$JAEGER_IP:4317

    Then set vLLM's service name for OpenTelemetry, enable insecure connections to Jaeger and run vLLM:

    export OTEL_SERVICE_NAME="vllm-server"
export OTEL_EXPORTER_OTLP_TRACES_INSECURE=true
vllm serve facebook/opt-125m --otlp-traces-endpoint="$OTEL_EXPORTER_OTLP_TRACES_ENDPOINT"

  4. In a new shell, send requests with trace context from a dummy client

    export JAEGER_IP=$(docker inspect --format '{{ .NetworkSettings.IPAddress }}' jaeger)
export OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=grpc://$JAEGER_IP:4317
export OTEL_EXPORTER_OTLP_TRACES_INSECURE=true
export OTEL_SERVICE_NAME="client-service"
python dummy_client.py

  5. Open Jaeger webui: http://localhost:16686/

    In the search pane, select vllm-server service and hit Find Traces. You should get a list of traces, one for each request. Traces

  6. Clicking on a trace will show its spans and their tags. In this demo, each trace has 2 spans. One from the dummy client containing the prompt text and one from vLLM containing metadata about the request. Spans details

Exporter Protocol

OpenTelemetry supports either grpc or http/protobuf as the transport protocol for trace data in the exporter. By default, grpc is used. To set http/protobuf as the protocol, configure the OTEL_EXPORTER_OTLP_TRACES_PROTOCOL environment variable as follows:

export OTEL_EXPORTER_OTLP_TRACES_PROTOCOL=http/protobuf
export OTEL_EXPORTER_OTLP_TRACES_ENDPOINT=http://$JAEGER_IP:4318/v1/traces
vllm serve facebook/opt-125m --otlp-traces-endpoint="$OTEL_EXPORTER_OTLP_TRACES_ENDPOINT"

Instrumentation of FastAPI

OpenTelemetry allows automatic instrumentation of FastAPI.

  1. Install the instrumentation library

    pip install opentelemetry-instrumentation-fastapi

  2. Run vLLM with opentelemetry-instrument

    opentelemetry-instrument vllm serve facebook/opt-125m

  3. Send a request to vLLM and find its trace in Jaeger. It should contain spans from FastAPI.

FastAPI Spans

Example materials

dummy_client.py 
# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

import requests
from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import BatchSpanProcessor, ConsoleSpanExporter
from opentelemetry.trace import SpanKind, set_tracer_provider
from opentelemetry.trace.propagation.tracecontext import TraceContextTextMapPropagator

trace_provider = TracerProvider()
set_tracer_provider(trace_provider)

trace_provider.add_span_processor(BatchSpanProcessor(OTLPSpanExporter()))
trace_provider.add_span_processor(BatchSpanProcessor(ConsoleSpanExporter()))

tracer = trace_provider.get_tracer("dummy-client")

url = "http://localhost:8000/v1/completions"
with tracer.start_as_current_span("client-span", kind=SpanKind.CLIENT) as span:
    prompt = "San Francisco is a"
    span.set_attribute("prompt", prompt)
    headers = {}
    TraceContextTextMapPropagator().inject(headers)
    payload = {
        "model": "facebook/opt-125m",
        "prompt": prompt,
        "max_tokens": 10,
        "n": 3,
        "use_beam_search": "true",
        "temperature": 0.0,
        # "stream": True,
    }
    response = requests.post(url, headers=headers, json=payload)