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Flask - 日誌記錄

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作者 Ned Hsu 7 分鐘閱讀

目標

  • 配置 Python 的 logging 模塊
  • 在 API 中記錄關鍵事件
  • 將日誌輸出到文件和控制台

步驟

  1. 準備環境

    • 繼續使用 flask_api/ 項目結構，激活虛擬環境：
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      # Windows: flask_api_env\Scripts\activate
# macOS/Linux: source flask_api_env/bin/activate

  2. 配置日誌

    • 修改 app/init.py，設置日誌：

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      from flask import Flask, jsonify, g
from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow
from flask_bcrypt import Bcrypt
import jwt
from functools import wraps
from .routes.v1.todos import todos_bp as todos_v1_bp
from .routes.v1.users import users_bp as users_v1_bp
from .routes.v1.posts import posts_bp as posts_v1_bp
from .routes.v2.todos import todos_bp as todos_v2_bp
from .routes.v2.posts import posts_bp as posts_v2_bp
from .config import config_map
import os
import logging
from logging.handlers import RotatingFileHandler

db = SQLAlchemy()
ma = Marshmallow()
bcrypt = Bcrypt()

def setup_logging(app):
    # 配置日誌
    if not app.debug:  # 僅在非調試模式下使用文件日誌
        handler = RotatingFileHandler('app.log', maxBytes=10000, backupCount=3)
        handler.setLevel(logging.INFO)
        formatter = logging.Formatter(
            '%(asctime)s %(levelname)s: %(message)s [in %(pathname)s:%(lineno)d]'
        )
        handler.setFormatter(formatter)
        app.logger.addHandler(handler)

    # 添加控制台輸出
    console_handler = logging.StreamHandler()
    console_handler.setLevel(logging.DEBUG)
    console_handler.setFormatter(logging.Formatter('%(asctime)s %(levelname)s: %(message)s'))
    app.logger.addHandler(console_handler)
    app.logger.setLevel(logging.DEBUG)

def create_app():
    app = Flask(__name__)
    env = os.getenv('FLASK_ENV', 'development')
    app.config.from_object(config_map[env])
    db.init_app(app)
    ma.init_app(app)
    bcrypt.init_app(app)
    setup_logging(app)  # 初始化日誌

    app.register_blueprint(todos_v1_bp, url_prefix='/api/v1')
    app.register_blueprint(users_v1_bp, url_prefix='/api/v1')
    app.register_blueprint(posts_v1_bp, url_prefix='/api/v1')
    app.register_blueprint(todos_v2_bp, url_prefix='/api/v2')
    app.register_blueprint(posts_v2_bp, url_prefix='/api/v2')

    @app.errorhandler(404)
    def not_found(error):
        app.logger.error(f'404 error: {str(error)}')
        return jsonify({'error': 'Not Found', 'message': str(error)}), 404

    @app.errorhandler(400)
    def bad_request(error):
        app.logger.warning(f'400 error: {str(error)}')
        return jsonify({'error': 'Bad Request', 'message': str(error)}), 400

    @app.errorhandler(500)
    def internal_error(error):
        app.logger.critical(f'500 error: {str(error)}')
        return jsonify({'error': 'Internal Server Error', 'message': 'Something went wrong on our end'}), 500

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

    return app

def login_required(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        from .models import User
        token = request.headers.get('Authorization')
        if not token:
            abort(401, description='Missing token')
        try:
            if token.startswith('Bearer '):
                token = token[7:]
            data = jwt.decode(token, app.config['SECRET_KEY'], algorithms=['HS256'])
            user = User.query.get(data['user_id'])
            if not user:
                abort(401, description='Invalid token')
            g.current_user = user
        except jwt.ExpiredSignatureError:
            abort(401, description='Token has expired')
        except jwt.InvalidTokenError:
            abort(401, description='Invalid token')
        return f(*args, **kwargs)
    return decorated_function

def admin_required(f):
    @wraps(f)
    @login_required
    def decorated_function(*args, **kwargs):
        if not g.current_user.is_admin:
            abort(403, description='Admin access required')
        return f(*args, **kwargs)
    return decorated_function

    • 代碼解釋：

      • RotatingFileHandler：將日誌寫入文件，限制大小並保留備份。
      • app.logger：Flask 內置的日誌對象，可直接使用。
      • 日誌級別：DEBUG < INFO < WARNING < ERROR < CRITICAL。

  3. 在路由中添加日誌

    • 修改 app/routes/v1/users.py：

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      from flask import Blueprint, jsonify, request, abort
from ...models import User
from ... import db, admin_required
from ...schemas import user_schema, users_schema
import jwt
import datetime

users_bp = Blueprint('users_v1', __name__)

@users_bp.route('/users', methods=['GET'])
def get_users():
    users = User.query.all()
    users_bp.app.logger.info('Fetched all users')
    return jsonify({'users': users_schema.dump(users)})

@users_bp.route('/users', methods=['POST'])
def create_user():
    if not request.is_json:
        abort(400, description='Request must be JSON')
    data = request.get_json()
    if 'username' not in data or 'password' not in data:
        abort(400, description='Missing username or password')
    if User.query.filter_by(username=data['username']).first():
        abort(400, description='Username already exists')
    user = User(username=data['username'])
    user.set_password(data['password'])
    if data.get('role') in ['user', 'admin']:
        user.role = data['role']
    db.session.add(user)
    db.session.commit()
    users_bp.app.logger.info(f'User created: {user.username}')
    return jsonify(user_schema.dump(user)), 201

@users_bp.route('/login', methods=['POST'])
def login():
    if not request.is_json:
        abort(400, description='Request must be JSON')
    data = request.get_json()
    if 'username' not in data or 'password' not in data:
        abort(400, description='Missing username or password')
    user = User.query.filter_by(username=data['username']).first()
    if not user or not user.check_password(data['password']):
        users_bp.app.logger.warning(f'Failed login attempt for {data["username"]}')
        abort(401, description='Invalid credentials')
    token = jwt.encode({
        'user_id': user.id,
        'exp': datetime.datetime.utcnow() + datetime.timedelta(hours=24)
    }, users_bp.app.config['SECRET_KEY'], algorithm='HS256')
    users_bp.app.logger.info(f'User logged in: {user.username}')
    return jsonify({'token': token})

@users_bp.route('/users/<int:user_id>', methods=['DELETE'])
@admin_required
def delete_user(user_id):
    user = User.query.get_or_404(user_id, description='User not found')
    db.session.delete(user)
    db.session.commit()
    users_bp.app.logger.info(f'User deleted: {user.username} by admin {g.current_user.username}')
    return jsonify({'message': 'User deleted'}), 200

    • 修改 app/routes/v1/posts.py：

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      from flask import Blueprint, jsonify, request, abort, g
from ...models import Post, User
from ... import db, login_required, admin_required
from ...schemas import post_schema, posts_schema

posts_bp = Blueprint('posts_v1', __name__)

@posts_bp.route('/posts', methods=['GET'])
def get_posts():
    user_id = request.args.get('user_id', type=int)
    query = Post.query
    if user_id:
        query = query.filter_by(user_id=user_id)
    posts = query.all()
    posts_bp.app.logger.debug('Fetched posts')
    return jsonify({'posts': posts_schema.dump(posts)})

@posts_bp.route('/posts/<int:post_id>', methods=['GET'])
def get_post(post_id):
    post = Post.query.get_or_404(post_id, description='Post not found')
    return jsonify(post_schema.dump(post))

@posts_bp.route('/posts', methods=['POST'])
@login_required
def create_post():
    if not request.is_json:
        abort(400, description='Request must be JSON')
    data = request.get_json()
    if 'title' not in data or 'content' not in data:
        abort(400, description='Missing title or content')
    post = Post(
        title=data['title'],
        content=data['content'],
        user_id=g.current_user.id
    )
    db.session.add(post)
    db.session.commit()
    posts_bp.app.logger.info(f'Post created: {post.title} by {g.current_user.username}')
    return jsonify(post_schema.dump(post)), 201

@posts_bp.route('/posts/<int:post_id>', methods=['PUT'])
@login_required
def update_post(post_id):
    post = Post.query.get_or_404(post_id, description='Post not found')
    if post.user_id != g.current_user.id and not g.current_user.is_admin:
        abort(403, description='You can only edit your own posts unless you are an admin')
    if not request.is_json:
        abort(400, description='Request must be JSON')
    data = request.get_json()
    if 'title' in data:
        post.title = data['title']
    if 'content' in data:
        post.content = data['content']
    db.session.commit()
    posts_bp.app.logger.info(f'Post updated: {post.title} by {g.current_user.username}')
    return jsonify(post_schema.dump(post)), 200

@posts_bp.route('/posts/<int:post_id>', methods=['DELETE'])
@login_required
def delete_post(post_id):
    post = Post.query.get_or_404(post_id, description='Post not found')
    if post.user_id != g.current_user.id and not g.current_user.is_admin:
        abort(403, description='You can only delete your own posts unless you are an admin')
    db.session.delete(post)
    db.session.commit()
    posts_bp.app.logger.info(f'Post deleted: {post.title} by {g.current_user.username}')
    return jsonify({'message': 'Post deleted'}), 200

@posts_bp.route('/posts/all', methods=['DELETE'])
@admin_required
def delete_all_posts():
    Post.query.delete()
    db.session.commit()
    posts_bp.app.logger.warning(f'All posts deleted by admin {g.current_user.username}')
    return jsonify({'message': 'All posts deleted'}), 200

  4. 運行應用

    • 運行：
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      python run.py
    • 檢查控制台輸出，並在項目根目錄查看 app.log 文件（非 debug 模式下生成）。

  5. 測試 API

    • 使用 Postman 測試：
      • POST /api/v1/users：
        • Body：{"username": "alice", "password": "1234"}
        • 日誌：INFO: User created: alice
      • POST /api/v1/login（失敗）：
        • Body：{"username": "alice", "password": "wrong"}
        • 日誌：WARNING: Failed login attempt for alice
      • POST /api/v1/posts：
        • Headers：Authorization: Bearer <token>
        • Body：{"title": "My Post", "content": "Hello"}
        • 日誌：INFO: Post created: My Post by alice
      • DELETE /api/v1/posts/all（用 admin token）：
        • 日誌：WARNING: All posts deleted by admin <admin_username>

  6. 作業

    • 在 v2 的路由中添加類似的日誌記錄。
    • 修改日誌格式，添加當前請求的 URL（提示：使用 request.url）。

注意事項

  • RotatingFileHandler 只在 DEBUG=False 時生效，開發時主要看控制台。
  • 日誌級別應根據事件重要性選擇，例如錯誤用 ERROR，普通操作用 INFO。
  • 生產環境應考慮日誌存儲位置和輪轉策略。
Software, Python
Flask
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