Python 🐍 fullstack REST API app with Docker 🐳

By the end of this, you will understand and create a simple yet complete full stack app using the following:

• Next.js 14 (TypeScript)
• Tailwind CSS
• Flask (Python) + SQLAlchemy (ORM)
• PostgreSQL
• Docker
• Docker Compose

MANY technologies, but we'll keep the example as basic as possible to make it understandable.

We will proceed with a bottom-up approach, starting with the database and ending with the frontend.

If you prefer a video version

All the code is available for free on GitHub (link in video description).

Architecture

Before we start, here is a simple schema explaining the app's architecture.

• The frontend is a Next.js app with TypeScript and Tailwind CSS.

• The backend is written in Python, using Flask and SQLAlchemy.

• The database is PostgreSQL. We will use Docker to run the database, the backend, and also the frontend (you can also use Vercel). We will use Docker Compose to run the frontend, the backend, and the database together.

Prerequisites

• Basic knowledge of what is a frontend, a backend, an API, and a database
• Docker installed on your machine
• Python installed on your machine
• (optional) Postman or any other tool to make HTTP requests

1. Preparation

Create any folder you want, and then open it with your favorite code editor.

mkdir <YOUR_FOLDER>
cd <YOUR_FOLDER>
code .

Initialize a git repository.

git init
touch .gitignore

Populate the .gitignore file with the following content:

*node_modules

Create a file called compose.yml in the project's root.

touch compose.yml

Your projects should look like this:

We are ready to create the fullstack app and build it from the bottom up, starting with the database.

After each step, we will test the app's current state to ensure that everything is working as expected.

2. Database

We will use Postgres but not install it on our machine. Instead, we will use Docker to run it in a container. This way, we can easily start and stop the database without installing it on our machine.

Open the file compose.yml and add the following content:

services:
  db:
    container_name: db
    image: postgres:13
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: postgres
    ports:
      - 5432:5432
    volumes:
      - pgdata:/var/lib/postgresql/data

volumes:
  pgdata: {}

then type in your terminal

docker compose up -d

This will pull the Postgres image from Docker Hub and start the container. The -d flag means that the container will run in detached mode so we can continue to use the terminal.

Check if the container is running:

docker ps -a

You should see the container running.

Step into the db container

docker exec -it db psql -U postgres

Now that you are in the Postgres container, you can type:

\l
\dt

And you should see no relations.

You can leave the tab open. We will use it later.

3. Backend

The first step is done. Now, we will create the backend. We will use Go and Mux.

Create a new folder called backend and step into it:

mkdir backend
cd backend

Create 3 files

touch requirements.txt app.py flask.dockerfile

Your project should look like this:

🗒️ requirements.txt file

The requirements.txt file contains all the dependencies of the project. In our case we will need just 3.

Let's add them to the requirements.txt file:

flask
psycopg2-binary
Flask-SQLAlchemy
Flask-CORS

flask is the Python web framework we are gonna use.

psycopg2-binary is the driver to make the connection with the Postgres database.

Flask-SQLAlchemy is the ORM to make the queries to the database.

Flask-CORS is a Flask extension for handling Cross Origin Resource Sharing (CORS), making cross-origin AJAX possible.

---

🐍 app.py file

The app.py file is the main file of the application: it contains all the endpoints and the logic of the application.

Populate the app.py file as follows:

from flask import Flask, request, jsonify, make_response
from flask_sqlalchemy import SQLAlchemy
from flask_cors import CORS  
from os import environ

app = Flask(__name__)
CORS(app)  # Enable CORS for all routes
app.config['SQLALCHEMY_DATABASE_URI'] = environ.get('DATABASE_URL')
db = SQLAlchemy(app)

class User(db.Model):
  __tablename__ = 'users'
  id = db.Column(db.Integer, primary_key=True)
  name = db.Column(db.String(80), unique=True, nullable=False)
  email = db.Column(db.String(120), unique=True, nullable=False)

  def json(self):
    return {'id': self.id,'name': self.name, 'email': self.email}

db.create_all()

#create a test route
@app.route('/test', methods=['GET'])
def test():
  return make_response(jsonify({'message': 'test route'}), 200)

# create a user
@app.route('/api/flask/users', methods=['POST'])
def create_user():
  try:
    data = request.get_json()
    new_user = User(name=data['name'], email=data['email'])
    db.session.add(new_user)
    db.session.commit()

    return jsonify({
        'id': new_user.id,
        'name': new_user.name,
        'email': new_user.email
    }), 201
  except Exception as e:
      return make_response(jsonify({'message': 'error creating user', 'error': str(e)}), 500)

# get all users
@app.route('/api/flask/users', methods=['GET'])
def get_users():
  try:
    users = User.query.all()
    users_data = [{'id': user.id, 'name': user.name, 'email': user.email} for user in users]
    return jsonify(users_data), 200
  except Exception as e:
    return make_response(jsonify({'message': 'error getting users', 'error': str(e)}), 500)

# get a user by id
@app.route('/api/flask/users/<int:id>', methods=['GET'])
def get_user(id):
  try:
    user = User.query.filter_by(id=id).first()
    if user:
      return make_response(jsonify({'user': user.json()}), 200)
    return make_response(jsonify({'message': 'user not found'}), 404)
  except Exception as e:
    return make_response(jsonify({'message': 'error getting user', 'error': str(e)}), 500)

# update a user
@app.route('/api/flask/users/<int:id>', methods=['PUT'])
def update_user(id):
  try:
    user = User.query.filter_by(id=id).first()
    if user:
      data = request.get_json()
      user.name = data['name']
      user.email = data['email']
      db.session.commit()
      return make_response(jsonify({'message': 'user updated'}), 200)
    return make_response(jsonify({'message': 'user not found'}), 404)
  except Exception as e:
    return make_response(jsonify({'message': 'error updating user', 'error': str(e)}), 500)

# delete a user
@app.route('/api/flask/users/<int:id>', methods=['DELETE'])
def delete_user(id):
  try:
    user = User.query.filter_by(id=id).first()
    if user:
      db.session.delete(user)
      db.session.commit()
      return make_response(jsonify({'message': 'user deleted'}), 200)
    return make_response(jsonify({'message': 'user not found'}), 404)
  except Exception as e:
    return make_response(jsonify({'message': 'error deleting user', 'error': str(e)}), 500)

For an explanation, check: https://youtu.be/njNXTM6L0wc

We are importing:

• Flask as a framework
• request to handle the HTTP
• jsonify to handle the json format, not native in Python
• make_response to handle the HTTP responses
• flask_sqlalchemy to handle the db queries
• environ to handle the environment variables
• CORS to handle the Cross Origin Resource Sharing

Then we are creating the Flask app, configuring the database bu setting an environment variable called 'DATABASE_URL'. We will set it later in the docker-compose.yml file.

Then we are creating a User class with an id, a name and an email. the id will be autoincremented automatically by SQLAlchemy when we will create the users. the tablename = 'users' line is to define the name of the table in the database
We are creating Flask app, configuring the database bu setting an environment variable called 'DB_URL'. We will set it later in the docker-compose.yml file.

Then we are creating a User class with an id, a name and an email. the id will be autoincremented automatically by SQLAlchemy when we will create the users. the tablename = 'users' line is to define the name of the table in the database

An important line is db.create_all(). This will synchronize the database with the model defined, for example creating an "users" table.

Then we have 6 endpoints

test: just a test route
create a user: create a user with a name and an email
get all users: get all the users in the database
get one user: get one user by id
update one user: update one user by id
delete one user: delete one user by id
All the routes have error handling, for example if the user is not found, we will return a 404 HTTP response.

You can check a video-explanation here

🐳 Dockerize the Python app

The flask.dockerfile file is the file that will be used to containerize the Flask application.

Create a file called flask.dockerfile in the backend folder and add the following content:

FROM python:3.6-slim-buster

WORKDIR /app

COPY requirements.txt ./

RUN pip install -r requirements.txt

COPY . .

EXPOSE 4000

CMD [ "flask", "run", "--host=0.0.0.0", "--port=4000"]

FROM sets the base image to use. In this case we are using the python 3.6 slim buster image

WORKDIR sets the working directory inside the image

COPY requirements.txt ./ copies the requirements.txt file to the working directory

RUN pip install -r requirements.txt installs the requirements

COPY . . copies all the files in the current directory to the working directory

EXPOSE 4000 exposes the port 4000

CMD [ "flask", "run", "--host=0.0.0.0", "--port=4000"] sets the command to run when the container starts

For an explanation, check https://youtu.be/njNXTM6L0wc

🐙 update the compose.yml file

Update the compose.yml file in the project's root, adding the flaskapp service.

Below the updated version:

services:
  flaskapp:
    container_name: flaskapp
    image: flaskapp:1.0.0
    build:
      context: ./backend
      dockerfile: flask.dockerfile
    ports:
      - '4000:4000'
    restart: always
    environment:
      - DATABASE_URL=postgresql://postgres:postgres@db:5432/postgres
    depends_on:
      - db
  db:
    container_name: db
    image: postgres:13
    restart: always
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: postgres
    ports:
      - 5432:5432
    volumes:
      - pgdata:/var/lib/postgresql/data

volumes:
  pgdata:

For an explanation, check: https://youtu.be/njNXTM6L0wc

Build the image and run the container

Now, let's build the image and run the container:

docker compose build
docker compose up -d flaskapp
docker ps -a

We are now ready to test the backend.

🧪 Test the backend

We are now ready to test the backend.

You can use Postman or any other tool to make HTTP requests.

get all

Yoy can get all the users, but making a GET request to http://localhost:4000/api/flask/users

Create a new user

You can create a new user, but making a POST request to http://localhost:4000/api/flask/users

You can create 2 more users, to have a total of 3 users.

Let's check the database:

docker exec -it db psql -U postgres
select * from users;

update and delete a user

You can update a user, but making a PUT request to http://localhost:4000/api/flask/users/3

You can delete a user, but making a DELETE request to http://localhost:4000/api/flask/users/3

4. Frontend

Now that we have the backend up and running, we can proceed with the frontend.

We will use Next.js 14 with TypeScript and Tailwind.

From the root folder of the project, run this command:

npx create-next-app@latest --no-git

We use the --no-git flag because we already initialized a git repository at the project's root.

As options:

• What is your project named? frontend
• TypeScript? Yes
• EsLint? Yes
• Tailwind CSS? Yes
• Use the default directory structure? Yes
• App Router? No (not needed for this project)
• Customize the default import alias? No

This should create a new Next.js project in about one minute.

Step into the frontend folder:

cd frontend

Install Axios, we will use it to make HTTP requests (be sure to be in the frontend folder):

npm i axios

Before we proceed, try to run the project:

npm run dev

And open your browser at http://localhost:3000. You should see the default Next.js page.

🖋️ Modify the styles/global.css file

In the src/frontend/src/styles/globals.css file, replace the content with this one (to avoid some problems with Tailwind):

@tailwind base;
@tailwind components;
@tailwind utilities;

:root {
  --foreground-rgb: 0, 0, 0;
  --background-start-rgb: 214, 219, 220;
  --background-end-rgb: 255, 255, 255;
}

body {
  color: rgb(var(--foreground-rgb));
  background: linear-gradient(to bottom, transparent, rgb(var(--background-end-rgb))) rgb(var(--background-start-rgb));
}

Create new components

cd src
mkdir components
touch CardComponent.tsx UserInterface.tsx

In the /frontend/src folder, create a new folder called components and inside it create a new file called CardComponent.tsx and add the following content:

import React from 'react';

interface Card {
  id: number;
  name: string;
  email: string;
}

const CardComponent: React.FC<{ card: Card }> = ({ card }) => {
  return (
    <div className="bg-white shadow-lg rounded-lg p-2 mb-2 hover:bg-gray-100">
      <div className="text-sm text-gray-600">Id: {card.id}</div>
      <div className="text-lg font-semibold text-gray-800">{card.name}</div>
      <div className="text-md text-gray-700">{card.email}</div>
    </div>
  );
};

export default CardComponent;

Create a UserInterface component

In the /frontend/src/components folder, create a file called UserInterface.tsx and add the following content:

import React, { useState, useEffect } from 'react';
import axios from 'axios';
import CardComponent from './CardComponent';

interface User {
  id: number;
  name: string;
  email: string;
}

interface UserInterfaceProps {
  backendName: string;
}

const UserInterface: React.FC<UserInterfaceProps> = ({ backendName }) => {
  const apiUrl = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:4000';
  const [users, setUsers] = useState<User[]>([]);
  const [newUser, setNewUser] = useState({ name: '', email: '' });
  const [updateUser, setUpdateUser] = useState({ id: '', name: '', email: '' });

  const backgroundColors: { [key: string]: string } = {
    flask: 'bg-blue-500',
  };

  const buttonColors: { [key: string]: string } = {
    flask: 'bg-blue-700 hover:bg-blue-600',
  };

  const bgColor = backgroundColors[backendName as keyof typeof backgroundColors] || 'bg-gray-200';
  const btnColor = buttonColors[backendName as keyof typeof buttonColors] || 'bg-gray-500 hover:bg-gray-600';

  // Fetch users
  useEffect(() => {
    const fetchData = async () => {
      try {
        const response = await axios.get(`${apiUrl}/api/${backendName}/users`);
        setUsers(response.data.reverse());
      } catch (error) {
        console.error('Error fetching data:', error);
      }
    };

    fetchData();
  }, [backendName, apiUrl]);

  // Create a user
  const createUser = async (e: React.FormEvent<HTMLFormElement>) => {
    e.preventDefault();
    try {
      const response = await axios.post(`${apiUrl}/api/${backendName}/users`, newUser);
      setUsers([response.data, ...users]);
      setNewUser({ name: '', email: '' });
    } catch (error) {
      console.error('Error creating user:', error);
    }
  };

  // Update a user
  const handleUpdateUser = async (e: React.FormEvent<HTMLFormElement>) => {
    e.preventDefault();
    try {
      await axios.put(`${apiUrl}/api/${backendName}/users/${updateUser.id}`, { name: updateUser.name, email: updateUser.email });
      setUpdateUser({ id: '', name: '', email: '' });
      setUsers(
        users.map((user) => {
          if (user.id === parseInt(updateUser.id)) {
            return { ...user, name: updateUser.name, email: updateUser.email };
          }
          return user;
        })
      );
    } catch (error) {
      console.error('Error updating user:', error);
    }
  };

  // Delete a user
  const deleteUser = async (userId: number) => {
    try {
      await axios.delete(`${apiUrl}/api/${backendName}/users/${userId}`);
      setUsers(users.filter((user) => user.id !== userId));
    } catch (error) {
      console.error('Error deleting user:', error);
    }
  };

  return (
    <div className={`user-interface ${bgColor} ${backendName} w-full max-w-md p-4 my-4 rounded shadow`}>
      <img src={`/${backendName}logo.svg`} alt={`${backendName} Logo`} className="w-20 h-20 mb-6 mx-auto" />
      <h2 className="text-xl font-bold text-center text-white mb-6">{`${backendName.charAt(0).toUpperCase() + backendName.slice(1)} Backend`}</h2>

      {/* Form to add new user */}
      <form onSubmit={createUser} className="mb-6 p-4 bg-blue-100 rounded shadow">
        <input
          placeholder="Name"
          value={newUser.name}
          onChange={(e) => setNewUser({ ...newUser, name: e.target.value })}
          className="mb-2 w-full p-2 border border-gray-300 rounded"
        />

        <input
          placeholder="Email"
          value={newUser.email}
          onChange={(e) => setNewUser({ ...newUser, email: e.target.value })}
          className="mb-2 w-full p-2 border border-gray-300 rounded"
        />
        <button type="submit" className="w-full p-2 text-white bg-blue-500 rounded hover:bg-blue-600">
          Add User
        </button>
      </form>

      {/* Form to update user */}
      <form onSubmit={handleUpdateUser} className="mb-6 p-4 bg-blue-100 rounded shadow">
        <input
          placeholder="User Id"
          value={updateUser.id}
          onChange={(e) => setUpdateUser({ ...updateUser, id: e.target.value })}
          className="mb-2 w-full p-2 border border-gray-300 rounded"
        />
        <input
          placeholder="New Name"
          value={updateUser.name}
          onChange={(e) => setUpdateUser({ ...updateUser, name: e.target.value })}
          className="mb-2 w-full p-2 border border-gray-300 rounded"
        />
        <input
          placeholder="New Email"
          value={updateUser.email}
          onChange={(e) => setUpdateUser({ ...updateUser, email: e.target.value })}
          className="mb-2 w-full p-2 border border-gray-300 rounded"
        />
        <button type="submit" className="w-full p-2 text-white bg-green-500 rounded hover:bg-green-600">
          Update User
        </button>
      </form>

      {/* Display users */}
      <div className="space-y-4">
        {users.map((user) => (
          <div key={user.id} className="flex items-center justify-between bg-white p-4 rounded-lg shadow">
            <CardComponent card={user} />
            <button onClick={() => deleteUser(user.id)} className={`${btnColor} text-white py-2 px-4 rounded`}>
              Delete User
            </button>
          </div>
        ))}
      </div>
    </div>
  );
};

export default UserInterface;

For an explanation, check: https://youtu.be/njNXTM6L0wc

Modify the index.tsx file

Opne the index.tsx file and replace the content with the following:

import React from 'react';
import UserInterface from '../components/UserInterface';

const Home: React.FC = () => {
  return (
    <main className="flex flex-wrap justify-center items-start min-h-screen bg-gray-100">
      <div className="m-4">
        <UserInterface backendName="flask" />
      </div>
    </main>
  );
};

export default Home;

For the explanation, check: https://youtu.be/njNXTM6L0wc

Add the Flask/Python logo

In the /frontend/public folder, add the flasklogo.svg file.

Refresh the page and you should see the flask logo.

🧪 Test the frontend

We are now ready to test the frontend.

You can use the UI to insert, update, and delete users.

You can create a user directly from the UI

You can check the updated users in the POsgres database

docker exec -it db psql -U postgres
select * from users;

You can also update a user

And finally, you can delete a user, just by clicking on the "Delete User' button

You can check the content of the database with the following command:

docker exec -it db psql -U postgres
select * from users;

Dockerize the frontend

Deploy a Next.js app with Docker.

Change the next.config.js file in the frontend folder, replacing it with the following content:

/** @type {import('next').NextConfig} */
const nextConfig = {
  output: 'standalone',
};

module.exports = nextConfig;

Create a file called .dockerignore in the frontend folder and add the following content:

touch .dockerignore next.dockerfile

next.dockerfile
.dockerignore
node_modules
npm-debug.log
README.md
.next
.git

To dockerize the Next.js application, we will use the official Dockerfile provided by Vercel:

You can find it here: https://github.com/vercel/next.js/blob/canary/examples/with-docker/Dockerfile

Create a file called next.dockerfile in the frontend folder and add the following content (it's directly from the vercel official docker example)

FROM node:18-alpine AS base

# Install dependencies only when needed
FROM base AS deps
# Check https://github.com/nodejs/docker-node/tree/b4117f9333da4138b03a546ec926ef50a31506c3#nodealpine to understand why libc6-compat might be needed.
RUN apk add --no-cache libc6-compat
WORKDIR /app

# Install dependencies based on the preferred package manager
COPY package.json yarn.lock* package-lock.json* pnpm-lock.yaml* ./
RUN \
  if [ -f yarn.lock ]; then yarn --frozen-lockfile; \
  elif [ -f package-lock.json ]; then npm ci; \
  elif [ -f pnpm-lock.yaml ]; then yarn global add pnpm && pnpm i --frozen-lockfile; \
  else echo "Lockfile not found." && exit 1; \
  fi


# Rebuild the source code only when needed
FROM base AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .

# Next.js collects completely anonymous telemetry data about general usage.
# Learn more here: https://nextjs.org/telemetry
# Uncomment the following line in case you want to disable telemetry during the build.
# ENV NEXT_TELEMETRY_DISABLED 1

RUN yarn build && ls -l /app/.next


# If using npm comment out above and use below instead
# RUN npm run build

# Production image, copy all the files and run next
FROM base AS runner
WORKDIR /app

ENV NODE_ENV production
# Uncomment the following line in case you want to disable telemetry during runtime.
# ENV NEXT_TELEMETRY_DISABLED 1

RUN addgroup --system --gid 1001 nodejs
RUN adduser --system --uid 1001 nextjs

COPY --from=builder /app/public ./public

# Set the correct permission for prerender cache
RUN mkdir .next
RUN chown nextjs:nodejs .next

# Automatically leverage output traces to reduce image size
# https://nextjs.org/docs/advanced-features/output-file-tracing
COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static

USER nextjs

EXPOSE 3000

ENV PORT 3000
# set hostname to localhost
ENV HOSTNAME "0.0.0.0"

# server.js is created by next build from the standalone output
# https://nextjs.org/docs/pages/api-reference/next-config-js/output
CMD ["node", "server.js"]

Now, let's update the compose.yaml file in the project's root, adding the nextapp service.

Below the updated version:

services:
  nextapp:
    container_name: nextapp
    image: nextapp:1.0.0
    build:
      context: ./frontend
      dockerfile: next.dockerfile
    ports:
      - "3000:3000"
    environment:
      - NEXT_PUBLIC_API_URL=http://localhost:4000
    depends_on:
      - flaskapp

  # flask service
  flaskapp:
    container_name: flaskapp
    image: flaskapp:1.0.0
    build:
      context: ./backend
      dockerfile: flask.dockerfile
    ports:
      - '4000:4000'
    restart: always
    environment:
      - DATABASE_URL=postgresql://postgres:postgres@db:5432/postgres
    depends_on:
      - db

  # db service
  db:
    container_name: db
    image: postgres:13
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: postgres
    ports:
      - 5432:5432
    volumes:
      - pgdata:/var/lib/postgresql/data

volumes:
  pgdata: {}

And now, let's build the image and run the container:

docker compose build
docker compose up -d nextapp

You can check if the 3 containers are running:

docker ps -a

If you have the 3 services running, should be good to go.

Before we wrap up, let's make a final test using the UI.

🧪 Test the frontend

As a final test, we can check if the frontend is working.

To create a new user, add a name and email

We can check the list of users from the UI or directly from the database:

docker exec -it db psql -U postgres
\dt
select * from users;

📝 Recap

We made it 🎉

We build a simple yet complete Python full-stack web app using:

• Next.js 14 (TypeScript)
• Tailwind CSS
• Flask (Python) + SQLAlchemy (ORM)
• PostgreSQL
• Docker
• Docker Compose

If you prefer a video version

All the code is available for free on GitHub (link in video description).

If you have any questions, comment below or in the video comments

You can find me here:
Francesco

Comments

[Robina]

Always used to read your article today I'm moderator it's an honor

[Francesco Ciulla]

Thank you Robina, highly appreciated! did you ever watch some video versions?

[Robina]

Yes, I also viewed the video, and initially, I thought it was someone else. Later, I realized it was you.

[Francesco Ciulla]

interesting! I try to be very consistent with thumbnails and style

[Robina]

yeah

[Andres Galindo]

Great stuff. Would also be interesting going into the deployment phase

[Francesco Ciulla]

thank you, for sure will do in an upcoming one

[Devarshi Shimpi]

Amazing article and video as always!!🔥

[Francesco Ciulla]

thank you !!