Apache2 PHP docker container, how to log errors as stderr and info as stdout to container log?

Question

I am currently using the official php:7.4-apache image and I wanted to log some info and errors to the docker logs.

I realize that PHP does not log directly, but logs to the Apache2 Server instead since this is the server interpreting PHP.

Still, I tried the direct approach using the information from the official docker docs:

<?php

error_log('testlog', 3, '/proc/self/fd/1');
error_log('testerror', 3, '/proc/self/fd/2');

This gave me a "failed to open stream, the file does not exist" warning.

I also noticed that simply calling error_log('test') creates the following log without being written to stderr:

[Tue Nov 10 11:39:46.005650 2020] [php7:notice] [pid 17] [client 172.25.0.1:56576] test

I tried to figure out if there were any special ways to send a message to Apache2 stdout/stderr, but I was not able to find anything useful.

Is there a way to achieve this or is this simply the wrong way to log PHP within containers?

!!EDIT:!!

So far I've managed to find out that the log definition in the original Dockerfile is handled in this file to /dev/stderr & /dev/stdout.

I also found the following possibility:

error_log('test', 3, 'php://stdout');
error_log('testerr', 3, 'php://stderr');

But this results in the following output:

> test 
> 172.25.0.1 - - [18/Nov/2020:13:19:48 +0000] "GET / HTTP/1.1" 200 229 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.193 Safari/537.36"
> testerr

The goal would be to have something like this:

custom_info_log('test');
custom_error_log('testerr');

output this:

> [Wed Nov 18 13:19:48.459874 2020] [php7:info] [pid 20] [client 172.25.0.1:57398] test
> [Wed Nov 18 13:19:48.459874 2020] [php7:error] [pid 20] [client 172.25.0.1:57398] testerr

Maybe it's help you - https://stackoverflow.com/questions/25787258/php-how-to-use-monolog-to-log-to-console-php-out — Dmitry Leiko, Nov 20 '20 at 14:19

score -1 · Answer 1 · answered Nov 25 '20 at 10:54

Don't know if that can help, but you can forward any output from PHP to a file using :

ob_start();

//
// your script ....
//

$filePath = "path/to/your/log/file"
$outstream = ob_get_flush();
ob_clean();

if(!($file = fopen($filePath,"wb")))
{
    echo "unable to open log file" ; 
}
fwrite($file, $outstream);
fclose($file);

So maybe you can create a file logging all your php output and forward this file content to your docker logs.

Apache2 PHP docker container, how to log errors as stderr and info as stdout to container log?

1 Answers1