Best way to log POST data in Apache?

Imagine you have a site API that accepts data in the form of GET requests with parameters, or as POST requests (say, with standard url-encoded, &-separated POST data). If you want to log and analyze API calls, the GET requests will be easy, because they will be in the apache log. Is there a simple way to get the POST data in the apache log as well?

(Of course we could log the POST data explicitly in the application, but I'd like to have an configuration-level way that let me not worry about it in code.)

Use Apache's mod_dumpio. Be careful for obvious reasons.

Note that mod_dumpio stops logging binary payloads at the first null character. For example a multipart/form-data upload of a gzip'd file will probably only show the first few bytes with mod_dumpio.

Also note that Apache might not mention this module in httpd.conf even when it's present in the /modules folder. Just manually adding LoadModule will work fine.

You can install mod_security and put in /etc/modsecurity/modsecurity.conf:

SecRuleEngine On
SecAuditEngine On
SecAuditLog /var/log/apache2/modsec_audit.log
SecRequestBodyAccess on
SecAuditLogParts ABIJDFHZ