Docker-compose Flask, MYSQL PAIN

Question

Я новичок в Docker, и у меня есть простое приложение фляги, которое подсчитывает, сколько раз посетитель просматривал html-страницу.

Я пытаюсь сделать docker-compose с mysql внутри контейнера, но когда я открываю браузерон получает ошибку 255. Без докера, если я храню данные MYSQ на локальном хосте, он работает как положено.Что не так с моим docker-compose?

builtins.KeyError
KeyError: 255 

init.py:

from flask import Flask
from config import Config

from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config.from_object(Config)

db = SQLAlchemy(app)

from app import views

models.py:

from app import db

class Counter_v(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    count = db.Column(db.Integer)

    def __init__(self,count):
        self.count=count


    def __repr__(self):
        return "<Count {}>".format(self.count)

views.py:

from app import app, db
from app.models import Counter_v

@app.before_request
def before_request():
    db.create_all()

@app.route('/')
def index():
    v = Counter_v.query.first()
    print(v)
    if not v:
        v = Counter_v(count=0)
        v.count +=1
        db.session.add(v)
        db.session.commit()
    v.count +=1
    db.session.commit()
    return "Counter is " + str(v.count)

config.py:

import os

class Config(object):
    SECRET_KEY = 'you-will-never-guess'
    DEBUG = True
    DB_USERNAME = 'root'
    DB_PASSWORD = 'rootpass'
    DATABASE_NAME = 'counter'
    DB_HOST = 'db'
    DB_URI = "mysql+pymysql://%s:%s@%s/%s" % (DB_USERNAME, DB_PASSWORD, DB_HOST, DATABASE_NAME)

    MYSQL_ROOT_PASSWORD = 'rootpass'
    MYSQL_USER = 'root'
    MYSQL_ALLOW_EMPTY_PASSWORD = True

    SQLALCHEMY_DATABASE_URI = DB_URI
    SQLALCHEMY_TRACK_MODIFICATIONS = True

app_main.py:

from app import app

мои требования.py

Flask==0.12
PyMysql==0.7.4
Flask-SQLAlchemy==2.1

.env:

COMPOSE_PROJECT_NAME=web_test_3
PYTHONBUFFERED=true
FLASK_APP=app_main.py
FLASK_DEBUG=1

Dockerfile:

FROM python:3.7-slim
RUN apt-get update && apt-get install -y default-libmysqlclient-dev

RUN mkdir /app
WORKDIR /app

COPY requirements.txt requirements.txt

RUN pip install -r requirements.txt

COPY . .


CMD flask run --host=0.0.0.0 --port=5000

Docker-compose.yml:

version: '3'

services:
  web:
    build: .
    env_file:
      - '.env'
    ports:
      - '5000'
    volumes:
      - '.:/app'

  db:
    image: mysql
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: rootpass


  adminer:
    image: adminer
    restart: always
    ports:
      - 8080:8080

Полный возврат:

builtins.KeyError
KeyError: 255

Traceback (most recent call last)
File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1994, in __call__
return self.wsgi_app(environ, start_response)
File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1985, in wsgi_app
response = self.handle_exception(e)
File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1540, in handle_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python3.7/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1982, in wsgi_app
response = self.full_dispatch_request()
File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1614, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1517, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python3.7/site-packages/flask/_compat.py", line 33, in reraise
raise value
File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1610, in full_dispatch_request
rv = self.preprocess_request()
File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1831, in preprocess_request
rv = func()
File "/app/app/views.py", line 6, in before_request
db.create_all()
File "/usr/local/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 972, in create_all
self._execute_for_all_tables(app, bind, 'create_all')
File "/usr/local/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py", line 964, in _execute_for_all_tables
op(bind=self.get_engine(app, bind), **extra)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/schema.py", line 4200, in create_all
ddl.SchemaGenerator, self, checkfirst=checkfirst, tables=tables
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2010, in _run_visitor
with self._optional_conn_ctx_manager(connection) as conn:
File "/usr/local/lib/python3.7/contextlib.py", line 112, in __enter__
return next(self.gen)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2002, in _optional_conn_ctx_manager
with self.contextual_connect() as conn:
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2192, in contextual_connect
self._wrap_pool_connect(self.pool.connect, None),
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 2228, in _wrap_pool_connect
return fn()
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool.py", line 425, in connect
return _ConnectionFairy._checkout(self)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool.py", line 822, in _checkout
fairy = _ConnectionRecord.checkout(pool)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool.py", line 554, in checkout
rec = pool._do_get()
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool.py", line 1250, in _do_get
self._dec_overflow()
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/langhelpers.py", line 67, in __exit__
compat.reraise(exc_type, exc_value, exc_tb)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 277, in reraise
raise value
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool.py", line 1247, in _do_get
return self._create_connection()
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool.py", line 370, in _create_connection
return _ConnectionRecord(self)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool.py", line 499, in __init__
self.__connect(first_connect_check=True)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/pool.py", line 701, in __connect
connection = pool._invoke_creator(self)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/strategies.py", line 114, in connect
return dialect.connect(*cargs, **cparams)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/default.py", line 437, in connect
return self.dbapi.connect(*cargs, **cparams)
File "/usr/local/lib/python3.7/site-packages/pymysql/__init__.py", line 88, in Connect
return Connection(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/pymysql/connections.py", line 688, in __init__
self.connect()
File "/usr/local/lib/python3.7/site-packages/pymysql/connections.py", line 905, in connect
self._get_server_information()
File "/usr/local/lib/python3.7/site-packages/pymysql/connections.py", line 1231, in _get_server_information
self.server_charset = charset_by_id(lang).name
File "/usr/local/lib/python3.7/site-packages/pymysql/charset.py", line 34, in by_id
return self._by_id[id]
KeyError: 255
The debugger caught an exception in your WSGI application. You can now look at the traceback which led to the error.