ingress-nginx: Unable to load debugging information from the nginx compiled binary

NGINX Ingress controller version: 0.13

Kubernetes version (use kubectl version): 1.8.x

What happened: I need to instrument the nginx binary with a third party proprietary monitoring tool (AppMon), which involves loading an external agent that needs access to nginx’s debugging information generated at compile time.

What you expected to happen: Given the current build.sh script, I’d expect the nginx binary to contain its debugging symbols. The script does include the flag -g into CC_OPT (line 285).

However, a simple test using gdb shows me it cannot find the debug symbols in the compiled binary.

How to reproduce it (as minimally and precisely as possible):

This can be checked with a current build of the image, i.e. quay.io/kubernetes-ingress-controller/nginx:0.34, run the following:

$> docker run --rm --name nginx -it quay.io/kubernetes-ingress-controller/nginx:0.34 bash

root@26c49acb2520:/# apt-get update && apt-get install -y gdb

<snipped output>

root@26c49acb2520:/# gdb /usr/sbin/nginx
GNU gdb (Debian 7.12-6) 7.12.0.20161007-git
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /usr/sbin/nginx...(no debugging symbols found)...done.
(gdb) 

The message at the bottom is the focus: no debugging symbols found.

My team is willing to maintain a custom build of the nginx-controller image to incorporate the third party agent for monitoring, but we need the compiled binary to include debugging symbols.

Can anyone help?