Python MySQL Docker error: Unknown database named main when migrating

Question

I am trying to migrate my python changes to my docker project, however when I try to run the command python manage.py db migrate I get the error unknown database 'main', however when I look inside of my docker-compose.yml file I see that main is indeed defined inside of the MYSQL_DATABASE variable inside of the container db. I have tried some solutions found on StackOverflow as well as Github like getting the restart: always out of my docker-compose.yml script and making a Windows PowerShell script that will run to restart my docker container as found here: MYSQL Docker container gives "unknown database" error, and trying to change my DATA_SAVE_PATH variable and other such variables in my docker-compose.yml: https://github.com/laradock/laradock/issues/1017 and I have also tried to change the MYSQL_DATABASE variable to a different name but that doesn't work either.

Here is the full error that I am receiving when I run my code:

sqlalchemy.exc.OperationalError: (MySQLdb._exceptions.OperationalError) (1049, "Unknown database 'main'")
(Background on this error at: http://sqlalche.me/e/13/e3q8)

Here is my docker-compose.yml script:

version: '3.9'
services:
  backend:
    build: 
      context: .
      dockerfile: Dockerfile
    ports:
      - 8001:5000
    volumes: 
      - .:/app
    depends_on:
      - db

  db:
    image: mysql:5.7.22
    restart: always
    environment:
      MYSQL_DATABASE: main
      MYSQL_USER: root
      MYSQL_PASSWORD: root
      MYSQL_ROOT_PASSWORD: root
    volumes:
      - .dbdata:/var/lib/mysql
    ports:
      - 33067:3306

Here is my Dockerfile:

FROM python:3.9
ENV PYTHONUNBUFFERED 1
WORKDIR /app
COPY requirements.txt /app/requirements.txt
RUN pip install -r requirements.txt
COPY . /app
CMD python main.py

Here is my main.py file:

from flask_cors import CORS
from sqlalchemy import UniqueConstraint
from vegaaimain.vegamain import main
from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config["SQLALCHEMY_DATABASE_URI"] = 'mysql://root:root@db/main'
CORS(app)

db = SQLAlchemy(app)
 

class VegaScriptRun(db.Model):
    id = db.Column(db.Integer, primary_key=True, autoincrement=False)
    title = db.Column(db.String(200))
    description = db.Column(db.String(400))
    image = db.Column(db.String(200))
    main()

class VegaScriptUser(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer)
    title = db.Column(db.String(200))
    description = db.Column(db.String(400))
    image = db.Column(db.String(200))

    UniqueConstraint('user_id', 'title', 'description', 'image', name='user_experiment_unique')
@app.route('/')
def index():
    return 'Hello'

if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0')

And finally my manage.py file, and requirements.txt file:

from main import app, db
from flask_migrate import Migrate, MigrateCommand
from flask_script import Manager

migrate = Migrate(app, db)

manager = Manager(app)
manager.add_command('db', MigrateCommand)

if __name__ == '__main__':
    manager.run()

requirements.txt

Flask==1.1.2
Flask-SQLAlchemy==2.4.4
SQLAlchemy==1.3.20
Flask-Migrate==3.0.0
Flask-Script==2.0.6
Flask-Cors==3.0.9
requests==2.25.0
mysqlclient==2.0.1
pika==1.1.0
wolframalpha==5.0.0

What exactly am I missing or doing wrong here, thank you!

Answer 1

I solved this problem by looking in my .dbdata folder and found my service, I then changed the MYSQL_DATABASE variable and the app configuration to the same variable as MYSQL_DATABASE which was vegatest instead of main.

So I ran the same command python manager.py db migrate and I got a successful migration.