Logs wrapped with newlines even when output decoration is disabled

[siimsoni]

Description

When decorate_workers_output is disabled as a pool directive, and worker output is redirected to the main error log:

decorate_workers_output = no
catch_workers_output = yes

And error log is enabled in global php-fpm.conf:

error_log = /var/log/php8.3-fpm.log

When the following code is executed in an FPM worker:

$err = array_fill(0, 128, "banana");
file_put_contents("php://stderr", json_encode($err));

error_log contains this:

["banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","bana
na","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana"]

But I expected the logged contents to be this instead:

["banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana","banana"]

Links:

• https://github.com/php/php-src/blob/PHP-8.3.2/sapi/fpm/fpm/fpm_stdio.c#L196-L197
• https://pracucci.com/php-on-kubernetes-application-logging-via-unix-pipe.html

PHP Version

PHP 8.3.2

Operating System

No response

[siimsoni]

This may be intentional, as it is possible to set log_limit in global php-fpm.conf, which solves the issue when set to a high enough value. However, I think the common expectation would be that log contents are not modified when decorate_workers_output = no is set. If this cannot be changed, then I propose to add a note about it to decorate_workers_output documentation.

[devnexen]

I ll leave bukka to explain the rationale.

[bukka]

The decorate_workers_output is just about adding message prefix and suffix around the logged data. The log_limit is for setting the line limit so this should not be overwritten. I just double checked and we always do wrapping except external log (logging directly in child to sapi). We could potentially allow disabling of wrapping and just truncate it but not sure if it's really useful. Most of the time it should be just resolved by setting high log_limit. I think we should bump its value in PHP 9 so this problem won't be that visible.

I agree that we can add more explanation to the config for this so I will keep it open as a feature request.