Log only real fatal errors from PHP-FPM in Docker container
I’m using NGINX with PHP-FPM in seperated Docker containers. I want to get errors only to stderr, so that I can collect them on a centralized log-server. Problem is: I’m using WP and seems to have some not well written plugins. They work but cause warnings like this:
2017/06/17 01:16:08 [error] 7#7: *1 FastCGI sent in stderr: “PHP
message: PHP Warning: Parameter 1 to wp_default_scripts() expected to
be a reference, value given in /www/wp-includes/plugin.php on line 601
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Example script for testing, which should give me a fatal error in the stderr:
PHP-FPM was configured to log errors to stderr like this:
[global] log_level = error error_log = /proc/self/fd/2
I’m wondering that this gave me nothing in the script above. Just after I switched the
log_level to at least
notice, I got the exception on the console of the docker container:
[17-Jun-2017 01:45:35] WARNING: [pool www] child 8 said into stderr:
“NOTICE: PHP message: PHP Fatal error: Uncaught Error: Call to
undefined function not_existing_func() in /www/x.php:2”
Why the hell is this a notice? For me we’ve clearly a fatal error here like the message indicates, cause the script can’t continue (and we get a 500 error in the browser, of course). It can’t be true that I have to set
notice so that I don’t miss fatal errors which are delcared as warnings. And simultaneously, my logs get filled with trash warnings from wordpress themes, plugins and so on, that I haven’t developed and I don’t want to fix for update reasons…
I tried a bit and found out that
php.ini is essential for PHP-FPM to get any information. But the log level from
error_reporting seems wired too. For testing purpose, I used the following configuration:
display_errors = Off log_errors = On error_log = /proc/self/fd/2 ;error_reporting = E_COMPILE_ERROR|E_ERROR|E_CORE_ERROR error_reporting = 0
Result: I got notices, but NO info about my fatal error…
One Solution collect form web for “Log only real fatal errors from PHP-FPM in Docker container”
First of all, I learned that I was wrong: WordPress is the root cause for this issue, not PHP directly. It’s a known fact that WP manipulates the
error_reporting when debugging is enabled, so I checked to define
false in my config. BUT even having this set, the documentation says
Except for ‘error_reporting’, WordPress will set this to 4983 if WP_DEBUG is defined as false.
So my settings to
php.ini were correct and sufficient. I don’t even need the php-fpm settings, when errors are redirected to stdout in the
How to prevent WordPress from manipulating the error reporting?
This is not so easy, too. Although the WordPress documentation says, that the
wp-config.php is a good place to set global wide settings like the error reporting, they god overwritten later to
4983. I don’t know where. Maybe it’s not even the Core of wordpress, but some poor developed plugin or theme.
We can handle this by adding
error_reporting to the disabled functions:
disable_functions = error_reporting
Now it’s not possible to overwrite our
error_reporting. I think this is the best solution to make sure, that we don’t get any other error reporting by external influence from plugins or themes. Also in the future. Since PHP allows such chaos, we need to reckon with such things.
Basically, we could criticize, that this pevent us from getting more logs by setting
WP_DEBUG to true. That’s right. But as we’re on a productive system, It seems wrong for me do to troubleshooting in such a way there. We shouldn’t do this on a application base, especially without
display_errors! Instead, the workflow to find problems should be a look at the error logs.
Fatal errors should always be logged and checked on a regular basis. If that is not enough,
error_reporting could be set on a higher level to get information about possible problems like warnings.