Varnish health check failing due to presence of id_prefix in env.php

[Nazar65]

Description (*)

The root of the issue has to do with the fix for GitHub-15828 and how pub/health_check.php works. In the release notes for 2.3.1 it says

Magento now sets the id_prefix option on prefix cache keys for the cache frontend during installation. If this option is not set, Magento uses the first 12 bits of the md5 hash of the absolute path to the Magento app/etc directory. But if this value is not exactly the same on all web servers, cache invalidation will not work.

Fixed Issues (if relevant)

1. Varnish health check failing due to presence of id_prefix in env.php #22143: Issue title

Manual testing scenarios (*)

1. Install a fresh copy of Magento 2.3.1
2. Configure the frontend cache to use Redis
3. Export varnish.vcl from admin panel and configure Varnish to sit in front of Apache per instructions at https://devdocs.magento.com/guides/v2.3/config-guide/varnish/config-varnish-configure.html
4. Try to load the site

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

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[Nazar65]

@orlangur i'm changed the solution, and add comment for better understanding. can you review changes ?

[orlangur]

Follow-up on Slack conversation with Nazar: we need a kind of health-check for cache type even when there is only one key in array.

[Nazar65]

I'm will provide solution soon.

[gody01]

Hello,
this PR just jumps over Redis cache check. It doesn't actually check, if redis actually works.

[Nazar65]

Hi @gody01 can you explain ?

[gody01]

Hi @gody01 can you explain ?

Sorry, my bad.
To fast on the keyboard. It seems OK.

[Nazar65]

Hi @orlangur, this is my observation, issue comes from redis config check at this point ->

  if (!isset($cacheConfig[ConfigOptionsListConstants::CONFIG_PATH_BACKEND]) ||
            !isset($cacheConfig[ConfigOptionsListConstants::CONFIG_PATH_BACKEND_OPTIONS])) {
            http_response_code(500);
            $logger->error("Cache configuration is invalid");
            exit(1);
        }

So before there was not any configuration due to missing id_prefix, but after some PR we have this option as default, so this "if" statement was fails because hes not found config options for redis, but this is true because i'm have no redis configuration just varnish, but i have 500 error, so basically we need to run in to this statement when redis is configured, but how we could do that ? we just need to check if we have backed options then do the test_cache, and if we have only id_prefix that's means we have no any redis configured and dont need to check this configuration, and simply i check in iteration that current config have only 1 key and this key is id_prefix that means that this is default configuration, and have no redis, so we don't need to check backed options. And if not, we check the backed options and do the test config, and this is how it before. Hope that this will help to progress on this PR.

[orlangur]

Thank for your investigation @Nazar65!

[magento-engcom-team]

Hi @orlangur, thank you for the review.
ENGCOM-5143 has been created to process this Pull Request

[VasylShvorak]

✔️ QA passed

[m2-assistant]

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