Separate cache_types from app/etc/config.php

[kassner]

Description

When trying to run Magento in a read-only filesystem, ideally both config.php and env.php should be read-only as well, but that breaks the ability of turning on/off any cache type in using php bin/magento cache:(disable|enable). This PR splits the cache_types key away from config.php, so system administrators can still guarantee that the config.php and all its values can't be changed during execution, but still allow the caches to be toggled by mounting app/etc/cache.php into a writable filesystem.

Fixed Issues (if relevant)

1. Fixes Read-only app/etc/ #26292

Manual testing scenarios

1. Deploy magento in a read-only filesystem;
2. Mount app/etc/cache.php in a writable filesystem (symbolic link works);
3. Use php bin/magento cache:disable

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 are green)

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[kandy]

Thanks for your contribution.
I believe that move the cache part to a separate file has the same drawback as having it in env.php.
Can I propose a slightly different approach to such a problem:
Let's modify logic of \Magento\Framework\App\DeploymentConfig and merge configuration from file with data from environment variables.
For example: for disabling Layout Cache you can set env variable MAGENTO_CACHE_TYPES__LAYOUT=0 (config key cache_types/layout)

[kassner]

I believe that move the cache part to a separate file has the same drawback as having it in env.php.

Not necessarily. env.php should definitely stay read-only, as being able to change the MySQL credentials in a running shop is a no-no. That could be overwritten in the cache.php by writing the db credentials sections to it, but that could be mitigated by guaranteeing that the env.php will be merged last.

For example: for disabling Layout Cache you can set env variable MAGENTO_CACHE_TYPES__LAYOUT=0 (config key cache_types/layout)

If you run magento in kubernetes, changing the environment variable for PHP-FPM means changing the deployment, which has the same effort as changing a read-only file, so in the end it means the caches can’t be toggled in runtime anymore.

[kassner]

BTW: I rather discuss the appropriate solution for this problem in the original ticket (#26292), as this PR is just one of the possible implementations.

[ihor-sviziev]

Moved to #26292 (comment)

[kassner]

@ihor-sviziev please open this discussion in #26292.

[ihor-sviziev]

@magento run all tests

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[hostep]

@ihor-sviziev: should we change the target branch to 2.4-develop again? Because 2.5 is seemingly never going to happen in the near future (and maybe never at all) as far as I know?

[ihor-sviziev]

@hostep I think yes, but general question if we can accept it at all due to this is a backward incompatible change

[engcom-Hotel]

Hello @kassner,

Thanks for the contribution!

As this PR is targeted to the 2.5-develop branch, we are not processing the PRs with 2.5-develop for now. So I request you to please change the target to 2.4-develop so that we can move further with this PR.

Till the time we are moving this PR on hold.

Thanks

[sinhaparul]

We are currently processing PRs targeted to 2.4-develop only. So, removing this from the community picked backlog for now.