Built-in FPC cache is broken in 2.4.7 for some configurations

[thlassche]

Preconditions and environment

• Magento version: 2.4.7
• Use built in FPC
• Have aMAGE_RUN_CODE parameter set

Steps to reproduce

1. Enable built-in FPC
2. Have a MAGE_RUN_CODE parameter in your $_SERVER array
3. Load a frontend page
4. Load the same page again

Expected result

Page is cached, and in developer mode a header X-Magento-Cache-Debug: HIT is set

Actual result

Page is uncached, and in developer mode a header X-Magento-Cache-Debug: MISS is set

Additional information

In 2.4.7 the identifier for saving a page to cache was decoupled from the fetching identifier:

magento2/app/code/Magento/PageCache/Model/App/Request/Http/IdentifierForSave.php

Line 18 in 725b648

class IdentifierForSave implements IdentifierInterface

However the fetching identifier has plugins on it that prepend the cache key with some parameters:

magento2/app/code/Magento/PageCache/Model/App/CacheIdentifierPlugin.php

Line 67 in 725b648

$identifierPrefix .= StoreManager::PARAM_RUN_TYPE . '=' . $runType . '|';

That plugin is not added to the saving part, hence the key will always mismatch if there are additional parameters

Release note

No response

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @thlassche. Thank you for your report.
To speed up processing of this issue, make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, Add a comment to the issue:

• @magento give me 2.4-develop instance - upcoming 2.4.x release
• For more details, review the Magento Contributor Assistant documentation.
• Add a comment to assign the issue: @magento I am working on this
• To learn more about issue processing workflow, refer to the Code Contributions.

---

Join Magento Community Engineering Slack and ask your questions in #github channel.
⚠️ According to the Magento Contribution requirements, all issues must go through the Community Contributions Triage process. Community Contributions Triage is a public meeting.
🕙 You can find the schedule on the Magento Community Calendar page.
📞 The triage of issues happens in the queue order. If you want to speed up the delivery of your contribution, join the Community Contributions Triage session to discuss the appropriate ticket.

[thlassche]

Workaround, add this in a module:

<namespace>\<module>\Plugin\CacheIdentifierPlugin.php

<?php
namespace <namespace>\<module>\Plugin;
use Magento\PageCache\Model\App\Request\Http\IdentifierForSave;
use Magento\Store\Model\StoreManager;

class CacheIdentifierPlugin
{
    /**
     * @var \Magento\Framework\View\DesignExceptions
     */
    private $designExceptions;

    /**
     * @var \Magento\Framework\App\RequestInterface
     */
    private $request;

    /**
     * @var \Magento\PageCache\Model\Config
     */
    private $config;

    /**
     * @param \Magento\Framework\View\DesignExceptions $designExceptions
     * @param \Magento\Framework\App\RequestInterface $request
     * @param \Magento\PageCache\Model\Config $config
     */
    public function __construct(
        \Magento\Framework\View\DesignExceptions $designExceptions,
        \Magento\Framework\App\RequestInterface $request,
        \Magento\PageCache\Model\Config $config
    ) {
        $this->designExceptions = $designExceptions;
        $this->request = $request;
        $this->config = $config;
    }
    
    public function afterGetValue(IdentifierForSave $identifier, $result)
    {
        if ($this->config->getType() === \Magento\PageCache\Model\Config::BUILT_IN && $this->config->isEnabled()) {
            $identifierPrefix = '';
            /* @phpstan-ignore-next-line */
            $ruleDesignException = $this->designExceptions->getThemeByRequest($this->request);
            if ($ruleDesignException !== false) {
                $identifierPrefix .= 'DESIGN' . '=' . $ruleDesignException . '|';
            }

            /* @phpstan-ignore-next-line */
            if ($runType = $this->request->getServerValue(StoreManager::PARAM_RUN_TYPE)) {
                $identifierPrefix .= StoreManager::PARAM_RUN_TYPE . '=' .  $runType . '|';
            }

            /* @phpstan-ignore-next-line */
            if ($runCode = $this->request->getServerValue(StoreManager::PARAM_RUN_CODE)) {
                $identifierPrefix .= StoreManager::PARAM_RUN_CODE . '=' . $runCode . '|';
            }

            return $identifierPrefix . $result;

        }
        return $result;
    }
}

<namespace>\<module>\etc\frontend\di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">

    <type name="Magento\PageCache\Model\App\Request\Http\IdentifierForSave">
        <plugin name="core-app-area-design-exception-plugin"
                type="<namespace>\<module>\Plugin\CacheIdentifierPlugin" sortOrder="10"/>
    </type>
</config>

[m2-assistant]

Hi @engcom-Hotel. Thank you for working on this issue.
In order to make sure that issue has enough information and ready for development, please read and check the following instruction: 👇

• 1. Verify that issue has all the required information. (Preconditions, Steps to reproduce, Expected result, Actual result).
• 2. Verify that issue has a meaningful description and provides enough information to reproduce the issue.
• 3. Add Area: XXXXX label to the ticket, indicating the functional areas it may be related to.
• 4. Verify that the issue is reproducible on 2.4-develop branch
  Details

  - Add the comment @magento give me 2.4-develop instance to deploy test instance on Magento infrastructure.
  - If the issue is reproducible on 2.4-develop branch, please, add the label Reproduced on 2.4.x.
  - If the issue is not reproducible, add your comment that issue is not reproducible and close the issue and stop verification process here!
• 5. Add label Issue: Confirmed once verification is complete.
• 6. Make sure that automatic system confirms that report has been added to the backlog.

[engcom-Hotel]

Hello @thlassche,

Thanks for the report and collaboration!

We have tried to reproduce the issue in both 2.4.7 and 2.4-develop and the issue is reproducible in both instances.

But if we remove MAGE_RUN_CODE, the X-Magento-Cache-Debug is showing as HIT. Please refer to the below screenshot for reference:

With MAGE_RUN_CODE

Without MAGE_RUN_CODE

Hence confirming the issue.

Thanks

[github-jira-sync-bot]

✅ Jira issue https://jira.corp.adobe.com/browse/AC-11819 is successfully created for this GitHub issue.

[m2-assistant]

✅ Confirmed by @engcom-Hotel. Thank you for verifying the issue.
Issue Available: @engcom-Hotel, You will be automatically unassigned. Contributors/Maintainers can claim this issue to continue. To reclaim and continue work, reassign the ticket to yourself.

[digitalrisedorset]

@magento I am working on this

[digitalrisedorset]

I added a fix with the PR 38646. There is no automated tests at this time but the fix was added in the 2.4-develop branch and I verified both 2.4.7 and 2.4-develop had this issue

[ThisIsRuddy]

Cheers @digitalrisedorset

magento-module-page-cache-fpc-identifier.patch