Merlin_CacheWarmer (console-only)

Cache warming extension for Magento 2.4.5+ (PHP 8.1+) by Merlin.
No admin UI everything works via CLI.

v2.0.3 Fixes "The attribute 'length' is not allowed" error

v2.0.2 adds concurrency

Install

1. Copy the module to app/code/Merlin/CacheWarmer
2. Enable & deploy:

   bin/magento module:enable Merlin_CacheWarmer
   bin/magento setup:upgrade
   bin/magento setup:di:compile
   bin/magento cache:flush

Commands

Build queue

bash

bin/magento merlin:cache:queue:build [--sitemap <sitemap.xml|URL>] [--file <urls.txt>] [--add "https://a,https://b"] [--store-id 0] [--priority 0] [--not-before 60] [--clear] [--allow-duplicates]

• --sitemap: path or URL to a sitemap (also supports sitemap index).
• --file: text file with one URL per line.
• --add: comma-separated list of URLs to enqueue.
• --not-before: delay processing by N seconds.
• --clear: purge existing pending/processing items before enqueue.
• By default, duplicates in pending/processing are skipped.

Start processing

bin/magento merlin:cache:queue:start [--concurrency 10] [--limit 0] [--sleep 0] [--timeout 15] [--header "Key: Value" ...] [--user-agent "UA"] Added - Concurrency via --concurrency (default 8), using curl_multi

• Makes HTTP GET requests to each URL with headers:
  • User-Agent: MerlinCacheWarmer/1.0 (override with --user-agent)
  • Accept-Encoding: gzip, deflate
  • X-Merlin-CacheWarmer: 1
• Success = HTTP 2xx/3xx. Failures recorded with the reason.
• --sleep adds a delay (ms) between hits (nice for HAProxy/Varnish).

Status / remaining

bin/magento merlin:cache:queue:status [--list 20]

Shows counts and the next N pending URLs by priority/age.

Table

merlin_cachewarmer_queue:

• queue_id, url, store_id, priority, status, attempts, lock_uuid, response_code, duration_ms, last_error, not_before, created_at, updated_at

Notes for Varnish/HAProxy

• This module simply requests URLs; Varnish should cache responses as per your VCL.
• Consider allowing X-Merlin-CacheWarmer through HAProxy/Nginx logs for visibility.
• To reduce backend thundering herd, use --sleep and/or HAProxy rate limits.

Uninstall

Standard declarative schema table will be dropped on module removal if you implement an uninstall script (not included).

bin/magento module:disable Merlin_CacheWarmer