How to configure a custom access.log format in AEM

[#1]

I currently have the standard LogManager configuration that writes an access.log file for AEM.

The value of Message Pattern (org.apache.sling.commons.log.pattern) is "{5}". This logs the standard NCSA extended/combined log format.

Now I want to add custom fields, as described in:

Apache Sling :: Client Request Logging

However, I cannot add these format strings in the system console LogManager configuration like that. If I try it just stops working.

As I understand it, the "{5}" is just a placeholder for the default message being logged by the logger (which in this case is NCSA).

My org.apache.sling.engine.impl.log.RequestLogger is configured to an SLF4J logger.

The way I understand the section about MDC in Apache Sling :: Logging it sounds like it should be possible to pass through some custom log message format strings to the logger.

Now I tried

%d{dd.MM.yyyy HH:mm:ss.SSS} *%p* %h %l %u %t "%r" %>s %b "%\{Referer}i" "%\{User-Agent}i" "%\{Host}i"

But this does not work, logging stops in the access log when I try this.

Can someone point out the proper way to enter the access log format string in the Message Pattern field in the system console?

And no, I don't want to write my own logger in code - I prefer to just configure it and move on debugging (so please do not point out links to documentation of how to write my own custom loggers, I'm aware of those).

[#2]

Please check Customized Logging using SLF4J / MDC in AEM | Perficient Digital

[#3]

I have seen that link but it requires coding. As stated, I am looking for an option to simply configure it with the out of the box logger.

I just want to be able to modify the log format of the access log in the system console (e.g. like log format in Apache)

[#4]

Most of the custom logging requires you to map log to Java packages defined in code.