SSSD logs too many backtrace messages

This document (000020873) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 15 SP4

Situation

In SLES15 SP4 SSSD logs includes many backtrace messages despite the low debug level set.

Resolution

Backtrace log messages are debug messages generated because some fatal, critical or failures occurred in SSSD.
To avoid backtrace messages to be written in the logs it's better to find out the cause that triggers those messages and why some fatal, critical or failures occurred. Disabling backtrace messages could also make difficult to SUSE Support to troubleshoot some SSSD related issues.

If disabling backtrace log messages is required then it is possible to do so by setting the parameter...
debug_backtrace_enabled = false
... in every section of /etc/sssd/sssd.conf.

For example:

[sssd]
debug_backtrace_enabled = false
...

[nss]
debug_backtrace_enabled = false
...

[pam]
debug_backtrace_enabled = false
...

[domain/mydomain]
debug_backtrace_enabled = false

Finally, restart the sssd service:

systemctl daemon-reload
systemctl restart sssd.service

Cause

From version 2.5.0 SSSD logs also backtraces. The debug_backtrace_enabled parameter is now enabled by default. This change was introduced to try to debug hard-to-reproduce issues because most of the times the default log level is set to low.

SSSD stores detailed debug logs in an buffer and adds them to log files when some failure occurs. In the default configuration a backtrace is triggered when one of the following error levels occurs:

- Level 0: fatal failures (0x0010)
- Level 1: critical failures (0x0020)
- Level 2: serious failures (0x0040)

When some Fatal, Critical or Serious failures happen, a backtrace is triggered and all the detailed logs are also added to the log files.

Additional Information

https://manpages.opensuse.org/openSUSE%20Tumbleweed/sssd/sssd.conf.5.en.html

debug_backtrace_enabled (bool)

Enable debug backtrace.

In case SSSD is run with debug_level less than 9, everything is logged to a ring buffer in memory and flushed to a log file on any error up to and including `min(0x0040, debug_level)` (i.e. if debug_level is explicitly set to 0 or 1 then only those error levels will trigger backtrace, otherwise up to 2).

Feature is only supported for `logger == files` (i.e. setting doesn't have effect for other logger types).

Default: true

https://sssd.io/release-notes/sssd-2.5.0.html
SSSD 2.5.0 Release Notes
[New features]
If debug_backtrace_enabled is set to true then on any error all prior debug messages (to some limit) are printed even if debug_level is set to low value (for details see man sssd.conf: debug_backtrace_enabled description).

Disclaimer

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