Uvicorn server basics in FastAPI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Uvicorn in the context of FastAPI?

Uvicorn is a lightweight, fast server that runs FastAPI applications. It handles incoming web requests and sends responses.

beginner

How do you start a FastAPI app using Uvicorn from the command line?

Use the command: uvicorn main:app --reload where main is the Python file and app is the FastAPI instance.

beginner

What does the --reload option do when running Uvicorn?

It makes the server restart automatically when you change your code, so you don't have to stop and start it manually.

intermediate

Why is Uvicorn considered an ASGI server?

Because it supports ASGI (Asynchronous Server Gateway Interface), allowing FastAPI to handle asynchronous code efficiently.

beginner

How can you specify a different host and port when running Uvicorn?

Add options like --host 0.0.0.0 --port 8080 to the command to change where the server listens.

What command starts a FastAPI app with Uvicorn and auto-reloads on code changes?

A uvicorn main:app --reload

B python main.py

C fastapi run main.py

D uvicorn main:app --no-reload

The --reload flag enables auto-reloading, and uvicorn main:app runs the FastAPI app.

What does Uvicorn primarily do?

A Compiles Python code

B Runs FastAPI apps as a web server

C Manages databases

D Creates HTML templates

Uvicorn is a server that runs FastAPI apps and handles web requests.

Which protocol does Uvicorn support to handle asynchronous Python code?

A ASGI

B WSGI

C HTTP/1.0

D FTP

Uvicorn supports ASGI, which is designed for asynchronous Python web apps.

How do you change the port Uvicorn listens on?

A --debug

B --host 127.0.0.1

C --reload

D --port 8080

Use --port followed by the port number to change the listening port.

What happens if you omit the --reload flag when running Uvicorn?

A The server runs in debug mode

B The server will crash

C The server won't restart automatically on code changes

D The server listens on a random port

Without --reload, you must restart the server manually after code changes.

Explain how to run a FastAPI app using Uvicorn and why the --reload option is useful.

Think about how you test changes quickly during development.

Describe what makes Uvicorn suitable for running FastAPI apps compared to older servers.

Focus on how Uvicorn handles modern Python async features.