Add toggle and user agent filter for CacheBuster middleware (#4301) * Add toggle and user agent filter for CacheBuster middleware Closes #4290 [BUG] SillyTavern takes ~45 seconds to load initially * Use single instance of CacheBuster class * Cache config values * Consistent log header * Remove unnecessary empty line at the beginning of byaf.js

c627d77c468a5757ca9b3cfafa65137ea2a1cc69

Cohee <18619528+Cohee1207@users.noreply.github.com>

Signed

Parents: e0b020f211c1538ee2a0c52f5807119c08f72989

default/config.yaml+9 -0 Viewed

   # Enables disk caching for character cards. Improves performances with large card libraries.
   useDiskCache: true
 +# CACHE BUSTER CONFIGURATION
 +# IMPORTANT: Requires localhost or a domain with HTTPS, otherwise will not work!
 +cacheBuster:
 +  # Clear browser cache on first load or after uploading image files
 +  enabled: false
 +  # Only clear cache for the specified user agent regex pattern
 +  # Example: 'firefox|safari' (case-insensitive)
 +  userAgentPattern: ''
++
 # Allow secret keys exposure via API
 allowKeysExposure: false
 # Skip new default content checks

src/byaf.js+0 -1 Viewed

+-
 import sanitize from 'sanitize-filename';
 import { promises as fsPromises } from 'node:fs';
 import path from 'node:path';

src/endpoints/avatars.js+2 -1 Viewed

 import { getFileNameValidationFunction } from '../middleware/validateFileName.js';
 import { applyAvatarCropResize } from './characters.js';
 import { invalidateThumbnail } from './thumbnails.js';
 +import cacheBuster from '../middleware/cacheBuster.js';
 export const router = express.Router();

         // Remove previous thumbnail and bust cache if overwriting
         if (request.body.overwrite_name) {
             invalidateThumbnail(request.user.directories, 'persona', sanitize(request.body.overwrite_name));
 -            response.setHeader('Clear-Site-Data', '"cache"');
 +            cacheBuster.bust(request, response);
+        }
         const filename = request.body.overwrite_name || `${Date.now()}.png`;

src/endpoints/characters.js+2 -1 Viewed

 import { getUserDirectories } from '../users.js';
 import { getChatInfo } from './chats.js';
 import { formatByafAsCharacterCard, getCharacterFromByafManifest, getImageBufferFromByafCharacter, getScenarioFromByafManifest } from '../byaf.js';
 +import cacheBuster from '../middleware/cacheBuster.js';
 // With 100 MB limit it would take roughly 3000 characters to reach this limit
 const memoryCacheCapacity = getConfigValue('performance.memoryCacheCapacity', '100mb');

             fs.unlinkSync(newAvatarPath);
             // Bust cache to reload the new avatar
 -            response.setHeader('Clear-Site-Data', '"cache"');
 +            cacheBuster.bust(request, response);
+        }
         return response.sendStatus(200);

src/middleware/cacheBuster.js+92 -10 Viewed

 import crypto from 'node:crypto';
 import { DEFAULT_USER } from '../constants.js';
 +import { getConfigValue } from '../util.js';
 /**
  * MiddlewareSets the Clear-Site-Data header to bust the browser cache for the current user.
 - * @returns {import('express').RequestHandler}
 + */
 +class CacheBuster {
 +    /**
 +     * Handles/User-Agents that have already been busted.
 +     * @type {Set<string>}
 +     */
 +    #keys = new Set();
++
 +    /**
 +     * User agent regex to match against requests.
 +     * @type {RegExp | null}
      */
 -export default function getCacheBusterMiddleware() {
 +    #userAgentRegex = null;
++
 +    /**
 +     * Whether the cache buster is enabled.
 +     * @type {boolean | null}
 +     */
 +    #isEnabled = null;
++
 +    constructor() {
 +        this.#isEnabled = !!getConfigValue('cacheBuster.enabled', false, 'boolean');
 +        const userAgentPattern = getConfigValue('cacheBuster.userAgentPattern', '');
 +        if (userAgentPattern) {
 +            try {
 +                this.#userAgentRegex = new RegExp(userAgentPattern, 'i');
 +            } catch {
 +                console.error('[Cache Buster] Invalid user agent pattern:', userAgentPattern);
 +            }
 +        }
 +    }
++
     /**
 -     * @type {Set<string>} Handles/User-Agents that have already been busted.
 +     * Check if the cache should be busted for the given request.
 +     * @param {import('express').Request} request Express request object.
 +     * @param {import('express').Response} response Express response object.
 +     * @returns {boolean} Whether the cache should be busted.
      */
 -    const keys = new Set();
 +    shouldBust(request, response) {
 +        // If disabled with config, don't do anything
 +        if (!this.#isEnabled) {
 +            return false;
 +        }
++
 +        // If response headers are already sent or response is ended
 +        if (response.headersSent || response.writableEnded) {
 +            console.warn('[Cache Buster] Response ended or headers already sent');
 +            return false;
 +        }
++
 +        // Check if the user agent matches the configured pattern
 +        const userAgent = request.headers['user-agent'] || '';
++
 +        // Bust cache for all requests if no pattern is set
 +        if (!this.#userAgentRegex) {
 +            return true;
 +        }
++
 +        return this.#userAgentRegex.test(userAgent);
 +    }
 -    return (request, response, next) => {
 +    /**
 +     * Middleware to bust the browser cache for the current user.
 +     * @type {import('express').RequestHandler}
 +     */
 +    #middleware(request, response, next) {
         const handle = request.user?.profile?.handle || DEFAULT_USER.handle;
         const userAgent = request.headers['user-agent'] || '';
         const hash = crypto.createHash('sha256').update(userAgent).digest('hex');
         const key = `${handle}-${hash}`;
         if (this.#keys.has(key)) {
             return next();
+        }
         this.#keys.add(key);
 -        response.setHeader('Clear-Site-Data', '"cache"');
 +        this.bust(request, response);
         next();
 -    };
+    }
++
 +    /**
 +     * Middleware to bust the browser cache for the current user.
 +     * @returns {import('express').RequestHandler} The middleware function.
 +     */
 +    get middleware() {
 +        return this.#middleware.bind(this);
 +    }
++
 +    /**
 +     * Bust the cache for the given response.
 +     * @param {import('express').Request} request Express request object.
 +     * @param {import('express').Response} response Express response object.
 +     * @returns {void}
 +     */
 +    bust(request, response) {
 +        if (this.shouldBust(request, response)) {
 +            response.setHeader('Clear-Site-Data', '"cache"');
 +        }
 +    }
 +}
++
 +// Export a single instance for the entire application
 +const instance = new CacheBuster();
 +export default instance;

src/server-main.js+2 -2 Viewed

 import accessLoggerMiddleware, { getAccessLogPath, migrateAccessLog } from './middleware/accessLogWriter.js';
 import multerMonkeyPatch from './middleware/multerMonkeyPatch.js';
 import initRequestProxy from './request-proxy.js';
 import getCacheBusterMiddlewarecacheBuster from './middleware/cacheBuster.js';
 import corsProxyMiddleware from './middleware/corsProxy.js';
 import {
     getVersion,

 // Static files
 // Host index page
 app.get('/', getCacheBusterMiddleware()cacheBuster.middleware, (request, response) => {
     if (shouldRedirectToLogin(request)) {
         const query = request.url.split('?')[1];
         const redirectUrl = query ? `/login?${query}` : '/login';