Flask + Docker => No connection

I have a basic REST API implemented in Flask. I want to try using Docker to containerize it. I’m completely new to Docker, but based on what I was able to figure out on various forums, this is what I have set up.

Dockerfile

FROM python:3.11
WORKDIR     /app
COPY ./requirements.txt /app/requirements.txt
COPY .env /app/.env
COPY . /app
RUN python3 -m pip install -r /app/requirements.txt

EXPOSE 5000
ENTRYPOINT ["python3"]
CMD ["app.py", "--host=0.0.0.0"]

requirements.txt

aiohttp==3.8.6
aiohttp-retry==2.8.3
aiosignal==1.3.1
async-timeout==4.0.3
attrs==23.1.0
blinker==1.6.3
certifi==2023.7.22
charset-normalizer==3.3.1
click==8.1.7
distlib==0.3.7
filelock==3.12.4
Flask==2.3.0
Flask-Cors==4.0.0
flask-marshmallow==0.14.0
Flask-MySQL==1.5.2
Flask-MySQLdb==2.0.0
Flask-SQLAlchemy==3.1.1
frozenlist==1.4.0
idna==3.4
itsdangerous==2.1.2
Jinja2==3.1.2
MarkupSafe==2.1.3
marshmallow-sqlalchemy==0.29.0
multidict==6.0.4
mysqlclient==2.2.0
packaging==23.2
platformdirs==3.11.0
PyJWT==2.8.0
PyMySQL==1.1.0
python-dotenv==1.0.0
requests==2.31.0
six==1.16.0
SQLAlchemy==2.0.22
twilio==8.10.0
typing_extensions==4.8.0
urllib3==2.0.7
virtualenv==20.24.5
Werkzeug==3.0.0
yarl==1.9.2

app.py

from flask import Flask, request, jsonify, json
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.event import listens_for
from flaskext.mysql import MySQL
from flask_cors import CORS
from dataclasses import dataclass
from sqlalchemy import text
from urllib.parse import quote

app = Flask(__name__)
CORS(app, origins=["http://localhost:3000", "http://localhost:3000"])


db = SQLAlchemy()

mysql =MySQL()

@dataclass
class User(db.Model):

    __tablename__ = 'user'

    id = db.Column(db.Integer, primary_key=True)
    firstname = db.Column(db.String(46), nullable=False)#1
    lastname = db.Column(db.String(46), nullable=False)#1
    

    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname

    def as_dict(self):
        excluded_fields = ['id']
        return {field.name:getattr(self, field.name) for field in self.__table__.c if field.name not in excluded_fields}

@dataclass
class User(db.Model):

    __tablename__ = 'user'
    __table_args__ = {'extend_existing': True} 

    id = db.Column(db.Integer, primary_key=True)
    firstname = db.Column(db.String(46), nullable=False)#1
    lastname = db.Column(db.String(46), nullable=False)#1

    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname

    def as_dict(self):
        excluded_fields = ['id']
        return {field.name:getattr(self, field.name) for field in self.__table__.c if field.name not in excluded_fields}



app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://username:[email protected]/test'

db.init_app(app)
with app.app_context():
    db.create_all()


@app.route('/users', methods=['GET'])
def get_user():
    users = User.query.all()
    return jsonify(users)

@app.route('/user/<firstname>', methods=['GET'])
def user_byfirstname(firstname):
    user = User.query.filter_by(firstname = firstname).first()
    return jsonify(user.as_dict())

if __name__ == '__main__':
   app.run(debug=True)

App tree:

I then go to the Terminal, and run $ docker build -t myapp:latest .

The build is successful, and I can see my app listed in the Docker Desktop app

I then run

$ docker run --rm -it -p 8080:5000 myapp:latest
 * Running on http://127.0.0.1:5000
Press CTRL+C to quit
 * Restarting with stat
/usr/local/lib/python3.11/site-packages/flask_sqlalchemy/model.py:144: SAWarning: This declarative base already contains a class with the same class name and module name as __main__.User, and will be replaced in the string-lookup table.
  super().__init__(name, bases, d, **kwargs)
 * Debugger is active!
 * Debugger PIN: 581-248-767

Docker Desktop shows myapp is in use.

So far, so good. But this is where I start running into issues.

From host machine (through Postman) I cannot access the app on port 8080 with:

127.0.0.1:8080/users 

Postman throws the error : Error: read ECONNRESET

I really don’t know what to do or where to go from here, every source I’ve tried has given me a slight variation on what I have already attempted, and I’m no closer to getting this to work. Please help, thanks.