Hi!
I can write a proxy module for you that will save the headers you want to the MySQL database.
You need to tell me any custom headers you want to be saved so we can test, the software will have some kind of configuration but mostly will be on compile time, like what headers to keep watch and save.
It will be tested on latest nginx source code and shouldn't impact much the performance, but be aware that the SQL INSERT will delay the page serving time for a little and since this will have multithread we can't use much of prepared statements.
If you like we can split the program in two parts, one capture the data from nginx in plain C and log to a text file, and other read this text log and insert the decoded data into MySQL, that will impact less on nginx performance.
Any doubts please let me know.
Thanks for reading!
- Vinicius