Update docs for PHP Opcache use

[jandom]

• otherwise massive perf penalty
• tested against bare metal EC2

[tianon]

Thanks for the contribution!

In reading this, it feels like we're spending a lot of time duplicating common PHP documentation instead of something that's actually Docker-specific. Perhaps we could instead leave this as a very short hint somewhere and point to the official upstream documentation instead?

[jandom]

Oh hi, wow, thanks for having a look so quickly!

Absolutely, happy to follow your lead on this – the example is very verbose – just let me know how to best present it as a hit? Should I scrap the example and replace it with some documentation links?

Just to set the context for how this came about. I moved a large-ish production workload from "bare-metal" PHP ElasticBeanstalk to a multicontainer Docker ElasticBeanstalk and saw a pretty big performance drop (requests would take 0.6s rather than expected 0.3s).

Then went that rabbit hole and solved my problem, so wanted to spare people some time ("no, it's not the instance type being too small, not it's not an esoteric symfony configuration")

[jandom]

hi there @tianon – i've truncated the contribution a bit, pointing to some useful blogs instead of including a verbose opcache example, let me know if that's closer to what you wanted?

[tianon]

Frankly, I was expecting something even more terse, because IMO opcache isn't special/unique enough to warrant a separate section from the already-included "PHP Core Extensions" section which this is duplicating. I'd probably add something like this in the "Configuration" section that already talks about production usage:

In many production environments, it is also recommended to (build and) enable the PHP core OPcache extension for performance. See the upstream OPcache documentation for more details.

In many production environments, it is also recommended to (build and) enable the PHP core OPcache extension for performance.  See [the upstream OPcache documentation](https://www.php.net/manual/en/book.opcache.php) for more details.

[jandom]

Perfect, updated the wording to match what you said – it's now just a paragraph below the configuration section. Should be ready to go 🤞

[tianon]

Thanks for the contribution and for hanging with me while we worked this out 👍

[jandom]

@tianon no, thank you for the review – this doc will hopefully save people a ton of time (it would have saved me) because managed platforms (usually) ship with the extension auto-enabled

[jaylinski]

@yosifkit Why was this removed?

The conf.d-directory is a custom scan-dir, so it is not duplicating common PHP documentation.
https://github.com/docker-library/php/blob/master/7.4/alpine3.12/fpm/Dockerfile#L125

Without this info it is kind of hard to know were to put custom config files, that's why the info was there.

[tianon]

See a few lines up:

The default config can be customized by copying configuration files into the $PHP_INI_DIR/conf.d/ directory.

[jaylinski]

Thanks for the hint! (I must be blind 🤦‍♂️)