Python Flask SQLAlchemy 容器無法連接到 Z62A004B95946BB73AZ 容器

Question

我無法從 Flask 應用程序連接到我的 MySQL 數據庫。

I am learning to build web application with Python Flask from this tutorial but tried modifying some elements of it for experimenting with Docker. 即使不使用 docker-compose，我也無法從 web 應用程序連接到數據庫。

我先在應用程序日志（flask_test 容器）中給出錯誤回溯：

[2021-12-20 18:13:18 +0000] [1] [INFO] Starting gunicorn 20.1.0

[2021-12-20 18:13:18 +0000] [1] [INFO] Listening at: http://0.0.0.0:5000 (1)

[2021-12-20 18:13:18 +0000] [1] [INFO] Using worker: sync

[2021-12-20 18:13:18 +0000] [8] [INFO] Booting worker with pid: 8

[2021-12-20 18:13:19,105] INFO in __init__: Microblog startup

[2021-12-20 18:14:19,239] ERROR in app: Exception on /auth/register [POST]

Traceback (most recent call last):

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/connection.py", line 174, in _new_conn

    conn = connection.create_connection(

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/util/connection.py", line 96, in create_connection

    raise err

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/util/connection.py", line 86, in create_connection

    sock.connect(sa)

ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:


Traceback (most recent call last):

  File "/home/flasktest/venv/lib/python3.10/site-packages/elasticsearch/connection/http_urllib3.py", line 255, in perform_request

    response = self.pool.urlopen(

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 755, in urlopen

    retries = retries.increment(

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/util/retry.py", line 507, in increment

    raise six.reraise(type(error), error, _stacktrace)

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/packages/six.py", line 770, in reraise

    raise value

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 699, in urlopen

    httplib_response = self._make_request(

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/connectionpool.py", line 394, in _make_request

    conn.request(method, url, **httplib_request_kw)

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/connection.py", line 239, in request

    super(HTTPConnection, self).request(method, url, body=body, headers=headers)

  File "/usr/local/lib/python3.10/http/client.py", line 1282, in request

    self._send_request(method, url, body, headers, encode_chunked)

  File "/usr/local/lib/python3.10/http/client.py", line 1328, in _send_request

    self.endheaders(body, encode_chunked=encode_chunked)

  File "/usr/local/lib/python3.10/http/client.py", line 1277, in endheaders

    self._send_output(message_body, encode_chunked=encode_chunked)

  File "/usr/local/lib/python3.10/http/client.py", line 1037, in _send_output

    self.send(msg)

  File "/usr/local/lib/python3.10/http/client.py", line 975, in send

    self.connect()

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/connection.py", line 205, in connect

    conn = self._new_conn()

  File "/home/flasktest/venv/lib/python3.10/site-packages/urllib3/connection.py", line 186, in _new_conn

    raise NewConnectionError(

urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f73470be7d0>: Failed to establish a new connection: [Errno 111] Connection refused

這是 MySQL 容器（mysql_test）日志：

2021-12-20T18:13:14.094155Z 0 [System] [MY-013602] [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.

2021-12-20T18:13:14.098891Z 0 [Warning] [MY-011810] [Server] Insecure configuration for --pid-file: Location '/var/run/mysqld' in the path is accessible to all OS users. Consider choosing a different directory.

2021-12-20T18:13:14.110089Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '::' port: 33060, socket: /var/run/mysqld/mysqlx.sock

2021-12-20T18:13:14.110149Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.27'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server - GPL.

mbind: Operation not permitted

mbind: Operation not permitted

2021-12-20 18:13:10+00:00 [Note] [Entrypoint]: Creating database test_db

2021-12-20 18:13:10+00:00 [Note] [Entrypoint]: Creating user test_user

2021-12-20 18:13:10+00:00 [Note] [Entrypoint]: Giving user test_user access to schema test_db


2021-12-20 18:13:10+00:00 [Note] [Entrypoint]: Stopping temporary server

2021-12-20 18:13:13+00:00 [Note] [Entrypoint]: Temporary server stopped


2021-12-20 18:13:13+00:00 [Note] [Entrypoint]: MySQL init process done. Ready for start up.

這里是Python應用的起點（microblog.py）：

from app_pkg import create_app, cli

app = create_app()
cli.register(app)

這是 model class：

class User(UserMixin, SearchableMixin, db.Model):
    __searchable__ = ['username']
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64), index=True, unique=True)
    email = db.Column(db.String(120), index=True, unique=True)
    password_hash = db.Column(db.String(128))
    posts = db.relationship('Post', backref='author', lazy='dynamic')
    about_me = db.Column(db.String(140))
    last_seen = db.Column(db.DateTime, default=datetime.utcnow)
    followed = db.relationship(
        'User', secondary=followers,
        primaryjoin=(followers.c.follower_id == id),
        secondaryjoin=(followers.c.followed_id == id),
        backref=db.backref('followers', lazy='dynamic'), lazy='dynamic')

這是我的 compose.yaml：

version: '3'

services:

  python_app:
    container_name: flask_test
    build: .
    env_file: .env
    ports:
      - 8000:5000
    links:
      - mysqldb:dbserver
    depends_on:
      mysqldb:
        condition: service_healthy

  mysqldb:
    container_name: mysql_test
    image: mysql:latest
    env_file: database.conf
    volumes:
      - db-data:/var/lib/mysql
    healthcheck:
      test: ["CMD", "mysqladmin", "ping", "-h", "127.0.0.1", "--silent"]
      interval: 3s
      retries: 5
      start_period: 30s

volumes:
  db-data:

這是我的 Dockerfile：

FROM python:slim

RUN useradd flasktest

WORKDIR /home/flasktest

COPY requirements.txt requirements.txt
RUN python -m venv venv
RUN venv/bin/pip install -r requirements.txt
RUN venv/bin/pip install gunicorn pymysql cryptography

COPY app_pkg app_pkg
COPY migrations migrations
COPY microblog.py config.py boot.sh ./
RUN chmod +x boot.sh

ENV FLASK_APP microblog.py

RUN chown -R flasktest:flasktest ./
USER flasktest

EXPOSE 5000
ENTRYPOINT ["./boot.sh"]

最后，這是 boot.sh：

#!/bin/bash

source venv/bin/activate
while true; do
    flask db upgrade
    if [[ "$?" == "0" ]]; then
        break
    fi
    echo Upgrade command failed, retrying in 5 secs...
    sleep 5
done
exec gunicorn -b :5000 --access-logfile - --error-logfile - microblog:app

這些是應用程序中使用的一些必要的環境變量：

DATABASE_URL=mysql+pymysql://test_user:abc123@dbserver/test_db
MYSQL_ROOT_PASSWORD=root123
MYSQL_DATABASE=test_db
MYSQL_USER=test_user
MYSQL_PASSWORD=abc123

對不起，如果問題變得太長了。 我想在問題中提供盡可能多的細節。 讓我知道是否需要任何其他詳細信息。 過去一周我一直在嘗試調試此問題，但無法找到將應用程序與 sql 服務器連接的方法。

也讓我知道我是否應該嘗試任何特定的方法來嘗試調試此問題。

Answer 1

您當前正在使用 docker-compose dns 功能，其中您可以使用容器名稱作為在 docker-compose 中運行的服務的域名，這很整潔 - 除非您從 dbserver 重命名 mysqldb；）您是否重命名了 mysqldb？

如果您想繼續使用此功能，請將環境變量修改為：（將 dbserver 更改為 mysqldb）

DATABASE_URL=mysql+pymysql://test_user:abc123@mysqldb/test_db
...

如果您改為使用更明確的方法：

在您的 docker-compose 中，您需要通過以下方式將端口 3306 綁定到您的主機網絡

version: '3'

services:

  python_app:
    container_name: flask_test
    build: .
    env_file: .env
    ports:
      - 8000:5000
    links:
      - mysqldb:dbserver
    depends_on:
      mysqldb:
        condition: service_healthy

  mysqldb:
    container_name: mysql_test
    image: mysql:latest
    env_file: database.conf
    volumes:
      - db-data:/var/lib/mysql
    healthcheck:
      test: ["CMD", "mysqladmin", "ping", "-h", "127.0.0.1", "--silent"]
      interval: 3s
      retries: 5
      start_period: 30s
    ports:
      - 3306:3306
...

然后將環境變量更改為：

DATABASE_URL=mysql+pymysql://test_user:abc123@0.0.0.0/test_db

感謝您提供的所有信息，您沒有發布太多信息 - 全部需要:)