nagios/0 has disk perm error: DISK CRITICAL - /sys/kernel/debug/tracing is not accessible: Permission denied

[Alex Kavanagh]

As summary: the issue seems to be one where we should just exclude the check:

https://bugs.launchpad.net/ubuntu/+source/nagios-plugins/+bug/1516451/comments/22:

"Meanwhile, I've verified the issue seems relevant for newer ubuntu's too:

### Bionic
# /usr/lib/nagios/plugins/check_disk -w '20%' -c '10%' -e
DISK CRITICAL - /sys/kernel/debug/tracing is not accessible: Permission denied

### Eoan
# /usr/lib/nagios/plugins/check_disk -w '20%' -c '10%' -e
DISK CRITICAL - /sys/kernel/debug/tracing is not accessible: Permission denied

The issue was reported to Debian but don't think an action was taken on it:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=910267

Upstream also has recommendation to exclude tracefs for this issue:
http://www.dailyithelp.com/nagios-disk-critical-syskerneldebugtracing-is-not-accessible-permission/"