Recipe update at symfony/recipes#817

Doc update: symfony/symfony-docs#14176

Updated to src/preload.php

Thank you @nicolas-grekas.

@nicolas-grekas sorry, I'm not sure, but will this work on environments with read-only src/?

@nicolas-grekas any way to disable this behaviour? We currently have some issues with the preloading in sulu and this file should not be generated in our case.

Also I personally think cache:clear should nothing write in the src as its a generated cache file so I think a better place in my opinion would be var folder e.g.: var/.preload.php, maybe we can make a container parameter to make it configurable? Alternative to var I would think that config/.preload.php would maybe be a better place because I think its more similar to the config/bundles.php.

If the file stays at src/ or any folder in the git versioning, I think it would be better to create this file over a symfony/flex recipe so I can edit it the way I want it instead of creating it on every cache:clear.

var/ and config/ don't exist from the pov of the code. The code knows only about a cache-dir, a project-dir and the directory where the Kernel is found (by reflection).
Putting it anywhere else would need extra knowledge that is not present today.

But why is generating this file an issue? You didn't explain it. If preloading doesn't work with sulu, just don't use it?

I think it would be better to create this file over a symfony/flex recipe so I can edit it the way I want it instead of creating it on every cache:clear.

That'd mean hardcoding the env in the path (since the path contains "prod"). Doable, but this would need a reason (the current way has the benefit of being unconditional, thus quite easy to configure by default by hosters).

Please note that if you think this should be discussed seriously, a closed PR is not the place as it will be forgotten.

@nicolas-grekas oh sorry you are correct an own issue would be better created one here: #38334. Mostly the problem is on our side that its misleading devs using sulu that preloading is now possible over this file generated by symfony but its currently not in sulu so we would like to avoid generating of it until preloading is supported.