How to use Python FastAPI and NGINX to deploy a web app with docker compose

Background

FastAPI is a high performance web framework in Python 3.6+ that booming very fast recently. While NGINX is one of the most popular open source load balancer that been used widely as a reverse proxy in front of the app.

This article will show the steps to build a Hello World web app that hosting locally and set up a nginx server with it. All services will be deployed with docker compose. For more details about docker, please refer to here

Steps

1. Install Python and Poetry

There are bunch of ways to install Python. The official tutorial is from here or with some third party tools such as Anaconda(https://www.anaconda.com/).

There are also bunch of ways to manage the virtual environment in Python. Here we highly recommand a tool called poetry.

Notes: Please just skip this part if you have already got these ready on your local machine.

2. Create a new project with poetry

Start a new project with the command below. You can replace the hello-nginx-app with any other app name you like.

poetry new hello-nginx-app

Then add the library FastAPI with

poetry add fastapi

Now we have the place to start coding!

3. Write the app

First of all, as the app will be containerize with Docker, so we will add a Dockerfile in side the project. And the project structure looks like:

hello-nginx-app
├── pyproject.toml
├── README.rst
├── Dockerfile
├── hello-nginx-app
│   └── __init__.py
└── tests
    ├── __init__.py
    └── hello-nginx-app.py

Then we can create a main.py under hello-nginx-app/

And inside the main.py. add the code below:

from fastapi import FastAPI

app = FastAPI()

@app.get("/", status_code=200)
async def hello():
    return {"msg": "Hello World"}

Then in the Dockerfile, copy the code below:

FROM python:3.9.5-slim-buster

ARG app_root=/app
WORKDIR /app

COPY ./poetry.lock ./pyproject.toml ${app_root}/
COPY ./hello-nginx-app ${app_root}/

RUN pip install poetry==1.1.3
RUN poetry install && poetry cache clear --all -n pypi
CMD ["poetry", "run", "uvicorn", "main:app", "--host", "0.0.0.0"]

4. Prepare the NGINX

Then, we can create another folder for nginx, this folder will then be put together with the folder hello-nginx-app in another folder say fastapi-nginx-compose or whatever name you like.

The nginx folder’s structures will be

nginx
├── nginx.conf
├── Dockerfile

Here, the nginx.conf defines the configuration of the nginx while the dockerfile will strat a docker

in the nginx.conf, add code

events {
    worker_connections 100;
}

http {
    resolver 127.0.0.11 ipv6=off;
    server{
        listen 80;
        location / {
            proxy_pass http://api:8000;
        }
    }
}

and in the Dockerfile, add

FROM nginx

COPY nginx.conf /etc/nginx/nginx.conf

5. Docker Compose the App with Nginx

Now we can put the app folder and nginx folder together in another parent folder, and create a docker-compose.yaml file for setting up.

fastapi-nginx-compose
├── hello-nginx-app/
├── nginx/
├── docker-compose.yaml

The code in docker-compose.yaml

version: "3.9"

services:
    web:
        build: nginx
        ports:
          - 80:80
          - 443:443
        depends_on:
          - api
    api:
      build: airflow-token-api
      expose:
        - 8000
      ports:
        - 8000:8000

6. Run the app

Now it’s time to test if it’s running good:

At the parent folder, run

docker-compose up

Then you can open a browser and enter localhost

There should be printing out the {"msg": "Hello World"}