Python (Flask) serving Angular project's index.html file

To simplify the setup, consider using Angular CLI to place all of the files in a distribution directory during the build process, i.e., by specifying the outputPath in angular.json. You can use the angular.json assets section to move your Python files during the build.

angular.json

"your-project": {
  "root": "your-project-directory",
  "sourceRoot": "your-project-directory/src",
  "projectType": "application",
  "architect": {
    "build": {
    "builder": "@angular-devkit/build-angular:browser",
    "options": {
      "outputPath": "dist",
      "index": "your-project-directory/src/index.html",
      "main": "your-project-directory/src/main.ts",
      ...

      "assets": [
        {
          "glob": "**/*",
          "input": "your-project-directory/src/assets/",
          "output": "assets"
        },
        {
          "glob": "**/*",
          "input": "your-project-directory/src/python/",
          "output": "."
        }

---

In the top level of the dist directory, place your main.py with the basic Flask setup along with index.html. Note the static_proxy to ensure that supporting files are served.

main.py

from flask import Flask, send_from_directory

app = Flask(__name__)


@app.route('/<path:path>', methods=['GET'])
def static_proxy(path):
  return send_from_directory('./', path)


@app.route('/')
def root():
  return send_from_directory('./', 'index.html')


if __name__ == '__main__':
  # This is used when running locally only. When deploying use a webserver process 
  # such as Gunicorn to serve the app.
  app.run(host='127.0.0.1', port=8080, debug=True)


@app.errorhandler(500)
def server_error(e):
  return 'An internal error occurred [main.py] %s' % e, 500