How to generate OpenAPI docs (Swagger UI) page using static .yaml file with Flask?

from flask import Flask, render_template, send_from_directory

app = Flask(__name__)


@app.route('/docs')
def swagger_ui():
    return render_template('swagger_ui.html')


@app.route('/spec')
def get_spec():
    return send_from_directory(app.root_path, 'openapi.yaml')

- app.py
- templates
    - swagger_ui.html
- openapi.yaml

$ flask run