FastAPI OTLP instrumentation to Jaeger with Docker Compose

Question

I'm instrumenting a dummy FastAPI application using OpenTelemetry and Jaeger as the backend analysis tool.

I managed to make it work using the following two steps:

1. Run Jaeger (the Jaeger UI will be accessible on localhost:16686):

docker run -d --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:1.54

2. Start my dummy instrumented FastAPI app (reachable on localhost:8000):

opentelemetry-instrument --service_name dummy_app uvicorn app:app

When I make a request to the root endpoint of my API and check the Jaeger UI, I can successfully see my dummy_app as a service with the corresponding trace resulting of my call.

---

My problem is when I try to "dockerize" these steps in a docker-compose.yml file.

Here is my Dockerfile for my FastAPI dummy app:

FROM python:3.11.4

WORKDIR /code

COPY ./requirements.txt /code/requirements.txt

RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt

COPY ./app /code/app

CMD ["opentelemetry-instrument", "--service_name", "dummy_app", "uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

And my docker-compose.yml file with the two services defined:

version: '3'

services:
  dummy_app:
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - 8000:8000
  jaeger:
    image: jaegertracing/all-in-one:1.54.0
    container_name: jaeger
    restart: on-failure
    ports:
      - 6831:6831/udp
      - 6832:6832/udp
      - 5778:5778
      - 16686:16686
      - 4317:4317
      - 4318:4318
      - 14250:14250
      - 14268:14268
      - 14269:14269
      - 9411:9411
    environment:
      - COLLECTOR_ZIPKIN_HTTP_PORT=9411

I can reach the two services on localhost 8000 and 16686, respectively. But I can't find my dummy_app in the Jaeger UI list of instrumented services. While the two services are running, it seems they are not communicating together.

I am very new to both the OpenTelemetry and Docker technologies. Any help would be greatly appreciated for how to manage to properly run the services with Docker Compose.