{"id":113669,"date":"2020-06-01T08:00:00","date_gmt":"2020-06-01T08:00:00","guid":{"rendered":"https:\/\/fedoramagazine.org\/?p=31024"},"modified":"2020-06-01T08:00:00","modified_gmt":"2020-06-01T08:00:00","slug":"use-fastapi-to-build-web-services-in-python","status":"publish","type":"post","link":"https:\/\/sickgaming.net\/blog\/2020\/06\/01\/use-fastapi-to-build-web-services-in-python\/","title":{"rendered":"Use FastAPI to build web services in Python"},"content":{"rendered":"

FastAPI<\/a><\/em> is a modern Python web framework that leverage the latest Python improvement in asyncio. In this article you will see how to set up a container based development environment and implement a small web service with FastAPI.<\/p>\n

<\/span> <\/p>\n

Getting Started<\/h2>\n

The development environment can be set up using the Fedora container image. The following Dockerfile prepares the container image with FastAPI, Uvicorn<\/a> and aiofiles<\/a>.<\/p>\n

FROM fedora:32\nRUN dnf install -y python-pip \\ && dnf clean all \\ && pip install fastapi uvicorn aiofiles\nWORKDIR \/srv\nCMD [\"uvicorn\", \"main:app\", \"--reload\"]<\/pre>\n
After saving this Dockerfile in your working directory, build the container image using podman.<\/p>\n
$ podman build -t fastapi .\n$ podman images\nREPOSITORY TAG IMAGE ID CREATED SIZE\nlocalhost\/fastapi latest 01e974cabe8b 18 seconds ago 326 MB<\/pre>\n
Now let’s create a basic FastAPI program and run it using that container image.<\/p>\n
from fastapi import FastAPI app = FastAPI() @app.get(\"\/\")\nasync def root(): return {\"message\": \"Hello Fedora Magazine!\"}<\/pre>\n
Save that source code in a main.py<\/em> file and then run the following command to execute it:<\/p>\n
$ podman run --rm -v $PWD:\/srv:z -p 8000:8000 --name fastapi -d fastapi\n$ curl http:\/\/127.0.0.1:8000\n{\"message\":\"Hello Fedora Magazine!\"<\/pre>\n
You now have a running web service using FastAPI. Any changes to main.py<\/em> will be automatically reloaded. For example, try changing the “Hello Fedora Magazine!” message.<\/p>\n
To stop the application, run the following command. <\/p>\n
$ podman stop fastapi<\/pre>\n
Building a small web service<\/h2>\n
To really see the benefits of FastAPI and the performance improvement it brings (see comparison<\/a> with other Python web frameworks), let’s build an application that manipulates some I\/O. You can use the output of the dnf history<\/em> command as data for that application.<\/p>\n
First, save the output of that command in a file.<\/p>\n
$ dnf history | tail --lines=+3 > history.txt<\/pre>\n
The command is using tail<\/em> to remove the headers of dnf history<\/em> which are not needed by the application. Each dnf transaction can be represented with the following information: <\/p>\n