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function debug_cache_info

Maturity: 44

Flask debug endpoint that provides comprehensive cache busting information including static file versions, modification times, and cache buster values.

File:
/tf/active/vicechatdev/vice_ai/app.py
Lines:
1666 - 1694
Complexity:
moderate

Purpose

This endpoint serves as a debugging tool for developers to inspect cache busting mechanisms in a Flask application. It returns detailed information about static files (CSS and JS), their versions, modification times, file sizes, and the current cache buster configuration. This is useful for troubleshooting cache-related issues during development and ensuring proper cache invalidation strategies are working correctly.

Source Code

def debug_cache_info():
    """Debug endpoint to show cache busting information"""
    if not DEBUG_MODE:
        return jsonify({'error': 'Debug mode not enabled'}), 404
    
    static_files = {}
    if app.static_folder and os.path.exists(app.static_folder):
        for root, dirs, files in os.walk(app.static_folder):
            for file in files:
                if file.endswith(('.css', '.js')):
                    relative_path = os.path.relpath(os.path.join(root, file), app.static_folder)
                    full_path = os.path.join(root, file)
                    try:
                        mtime = os.path.getmtime(full_path)
                        static_files[relative_path] = {
                            'version': get_file_version(relative_path),
                            'mtime': datetime.fromtimestamp(mtime).isoformat(),
                            'size': os.path.getsize(full_path)
                        }
                    except OSError:
                        static_files[relative_path] = {'error': 'Could not read file stats'}
    
    return jsonify({
        'debug_mode': DEBUG_MODE,
        'cache_buster': get_cache_buster(),
        'startup_version': CACHE_BUST_VERSION,
        'static_files': static_files,
        'timestamp': datetime.now().isoformat()
    })

Return Value

Returns a Flask JSON response containing: 'debug_mode' (boolean indicating if debug is enabled), 'cache_buster' (current cache buster value from get_cache_buster()), 'startup_version' (CACHE_BUST_VERSION constant), 'static_files' (dictionary mapping relative file paths to objects with 'version', 'mtime', and 'size' keys), and 'timestamp' (ISO format timestamp of when the endpoint was called). If DEBUG_MODE is False, returns a 404 error with JSON error message.

Dependencies

  • flask
  • os
  • datetime

Required Imports

from flask import Flask
from flask import jsonify
import os
from datetime import datetime

Usage Example

# Assuming Flask app is configured with required globals and functions
# app = Flask(__name__)
# DEBUG_MODE = True
# CACHE_BUST_VERSION = '1.0.0'
# 
# def get_cache_buster():
#     return 'v1234567890'
# 
# def get_file_version(filepath):
#     return hashlib.md5(filepath.encode()).hexdigest()[:8]

@app.route('/debug/cache-info')
def debug_cache_info():
    # Function implementation here
    pass

# Access the endpoint:
# GET http://localhost:5000/debug/cache-info
# Response:
# {
#   "debug_mode": true,
#   "cache_buster": "v1234567890",
#   "startup_version": "1.0.0",
#   "static_files": {
#     "css/style.css": {
#       "version": "a1b2c3d4",
#       "mtime": "2024-01-15T10:30:00",
#       "size": 2048
#     }
#   },
#   "timestamp": "2024-01-15T12:00:00"
# }

Best Practices

  • This endpoint should only be enabled in development/debug mode and never in production environments
  • Ensure DEBUG_MODE is properly configured to prevent unauthorized access to internal file information
  • The endpoint walks the entire static folder tree, which could be slow for large applications - consider caching results if needed
  • Handle OSError exceptions gracefully when files cannot be accessed
  • Consider adding authentication/authorization checks even in debug mode to prevent information disclosure
  • The endpoint returns 404 when DEBUG_MODE is False, which is a security best practice to hide debug endpoints in production
  • Ensure get_file_version() and get_cache_buster() functions are implemented before using this endpoint

Tags

flask debug cache-busting static-files endpoint development monitoring file-versioning web-development diagnostics

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