python-fastapi-docker

Python FastAPI → Docker on publish

A single-file C# AppHost orchestrating a Python FastAPI service. In local development the app runs natively — Aspire creates a virtual environment from requirements.txt and launches uvicorn on your machine, no Dockerfile required. When you run aspire publish, Aspire auto-generates a Dockerfile for the Python app and emits a docker-compose.yaml, so the same code ships as a container image. Polyglot: C# AppHost, Python service.

Tech Stack

• AppHost: single-file apphost.cs with Aspire.Hosting.Python + Aspire.Hosting.Docker
• Service: Python FastAPI text-analyzer, served by uvicorn
• Dev runtime: native (venv on the host) — AddUvicornApp
• Publish artifact: an auto-generated Dockerfile + docker-compose.yaml

Run locally (native Python)

cd samples/python-fastapi-docker
aspire run

Aspire creates app/.venv, installs requirements.txt, and starts uvicorn on the host. Try it:

curl -k https://<api-endpoint>/api/info
curl -k -X POST https://<api-endpoint>/api/analyze \
-H 'Content-Type: application/json' \
-d '{"text":"Aspire makes polyglot apps easy. Easy!"}'

Publish as a Docker image

aspire publish -o ./compose-output

Aspire writes compose-output/api.Dockerfile (a production-ready, non-root Python image) and compose-output/docker-compose.yaml. Build and run it:

docker build -f compose-output/api.Dockerfile -t text-analyzer:local ./app
docker run -d -p 8080:8000 text-analyzer:local main:app --host 0.0.0.0 --port 8000
curl http://localhost:8080/api/info

What It Demonstrates

• AddUvicornApp("api", "app", "main:app") — a native Python dev experience (auto venv + uvicorn) with health checks and external endpoints.
• No hand-written Dockerfile: aspire publish generates one tailored to the detected Python version and dependencies, then references it from a compose file.
• One app model, two runtimes: native uvicorn for dev, a container image for publish/deploy.

Project Layout

apphost.cs single-file C# AppHost (Python + Docker Compose publish)
aspire.config.json points aspire at apphost.cs
apphost.run.json launch profiles (dashboard/OTLP ports)
app/
main.py FastAPI text-analyzer
requirements.txt fastapi + uvicorn (Aspire builds the venv from this)