python - Serving a front end created with create-react-app with Flask

Question

I have a Flask back-end with API routes which are accessed by a React single page application created using create-react-app. When using the create-react-app dev server, my Flask back end works.

I would like to serve the built (using npm run build) static React app from my Flask server. Building the React app leads to the following directory structure:

- build
  - static
    - css
        - style.[crypto].css
        - style.[crypto].css.map
    - js
        - main.[crypto].js
        - main.[crypto].js.map
  - index.html
  - service-worker.js
  - [more meta files]

By [crypto], I mean the randomly generated strings generated at build time.

Having received the index.html file, the browser then makes the following requests:

- GET /static/css/main.[crypto].css
- GET /static/css/main.[crypto].css
- GET /service-worker.js

How should I serve these files? I came up with this:

from flask import Blueprint, send_from_directory

static = Blueprint('static', __name__)

@static.route('/')
def serve_static_index():
    return send_from_directory('../client/build/', 'index.html')

@static.route('/static/<path:path>') # serve whatever the client requested in the static folder
def serve_static(path):
    return send_from_directory('../client/build/static/', path)

@static.route('/service-worker.js')
def serve_worker():
    return send_from_directory('../client/build/', 'service-worker.js')

This way, the static assets are successfully served.

On the other hand, I could incorporate this with the built-in Flask static utilities. But I do not understand how to configure this.

Is my solution robust enough? Is there a way to use built-in Flask features to serve these assets? Is there a better way to use create-react-app?

Answer 1

import os
from flask import Flask, send_from_directory

app = Flask(__name__, static_folder='react_app/build')

# Serve React App
@app.route('/', defaults={'path': ''})
@app.route('/<path:path>')
def serve(path):
    if path != "" and os.path.exists(app.static_folder + '/' + path):
        return send_from_directory(app.static_folder, path)
    else:
        return send_from_directory(app.static_folder, 'index.html')


if __name__ == '__main__':
    app.run(use_reloader=True, port=5000, threaded=True)

Thats what I ended up with. So bascially catch all routes, test if the path is a file => send file => else send the index.html. That way you can reload the react app from any route you wish and it does not break.