Magento 2.2.x – Fixing Cache Disabled Automatically Issue

If in your magento system,magento cron jobs are working properly then you define a cronjob which fire on midnight and clear cache.

<crontab>
    <jobs>
        <clean_cache_midnight><!-- identifier -->
             <schedule>
                 <cron_expr>0 0 * * *</cron_expr> <!-- run cronjob on midnight -->
             </schedule>
            <run>
                <model>MyModule_Model_Group_Class_Name::functionName</model>
            </run>
        </clean_cache_midnight>
    </jobs>
</crontab>

And class is

<?php
class [ModuleNameSpace]_[ModuleName]_Model_Mycron
{
    public function functionName(){

     /**
     * Flush all magento cache
     */
     Mage::app()->cleanCache();
    }
}

Full module:

create config.xml at app/code/community/Amit/Cleancache/etc/

<?xml version="1.0" encoding="utf-8"?>
<config>
<modules>
    <Amit_Cleancache>
        <version>1.0.0</version>
    </Amit_Cleancache>
</modules>
    <global>
        <models>
            <cleancache>
                <class>Amit_Cleancache_Model</class>
            </cleancache>
        </models>
    </global>
    <crontab>
        <jobs>
            <clean_cache_midnight><!-- identifier -->
                 <schedule>
                     <cron_expr>0 0 * * *</cron_expr> <!-- running cronjob on midnight -->
                 </schedule>
                <run>
                    <model>cleancache/Fire::fireCacheonMidnight</model>
                </run>
            </clean_cache_midnight>
        </jobs>
    </crontab>
</config>

File2: create Fire.php at app/code/community/Amit/Cleancache/Model/

code:

<?php
class Amit_Cleancache_Model_Fire
{
    public function fireCacheonMidnight(){

     /**
     * Flush all magento cache
     */
     Mage::app()->cleanCache();
    }
}

File3: module config file Amit_Cleancache.xml at app/etc/modules/

<?xml version="1.0" encoding="utf-8"?>
<config>
    <modules>
        <Amit_Cleancache>
            <active>true</active>
            <codePool>community</codePool>
        </Amit_Cleancache>
    </modules>
</config>

Using a local override/rewrite or whatever you prefer, be ready to make modifications to the Mage_Page_Block_Html_Head:: _prepareStaticAndSkinElements method.

You probably don't want your cache buster to use the current time on every page refresh, otherwise the standard asset caching on the browser end will be useless as every page will be showing the same version of the css file, but with a different name.

What you can do however, is make the asset version tied to a file which you can manually increment on every deployment. This way the browser caching works, unless you want to bust everyones caches when you deploy a new css change.

At the end of the the _prepareStaticAndSkinElements function you can modify it to look like

    $version = file_get_contents(BP . DS . 'assetversion.txt');

    $html = '';
    foreach ($items as $params => $rows) {
        // attempt to merge
        $mergedUrl = false;
        if ($mergeCallback) {
            $mergedUrl = call_user_func($mergeCallback, $rows);
        }
        // render elements
        $params = trim($params);
        $params = $params ? ' ' . $params : '';
        if ($mergedUrl) {
            $html .= sprintf($format, $mergedUrl, $params);
        } else {
            foreach ($rows as $src) {
                if ($version) {
                    $src.='?v=' . $version;
                }
                $html .= sprintf($format, $src, $params);
            }
        }
    }

This will get the contents of the file assetversion.txt which you will store in your project root, this can contain the number "1" to begin with. It will then append this as a ?v=1 parameter to all asset urls on the page.

When you next make a CSS change and need to bust through browser cache, simply increment the number in this text file then flush your magento caches.