Re: Rsyslog stdout and stderr

[Dieter Klünter <dieter@dkluenter.de>]

Am Fri, 15 Mar 2019 18:55:36 +0100
schrieb Abdelkader Chelouah <a.chelouah@gmail.com>:

> Le 10/03/2019 à 00:58, Howard Chu a écrit :
> > Abdelkader Chelouah wrote:  
> >> Hi,
> >>
> >> slapd 2.4.44
> >>
> >> OpenLDAP instance configure as a proxy (back-ldap)
> >>
> >>
> >>  From time to time, bind operations can take more than 5 sec.
> >> These latencies do not seem to come from a CPU or memory problem.
> >> I'm trying to see if the network can be the root cause of the
> >> issue. To debug the fonction ldap_sasl_bind
> >> (libraries/libldap/sasl.c), I activated trace loglevel (logs are
> >> manage by rsyslog). In the definition of ldap_sasl_bind, there is
> >>
> >> Debug( LDAP_DEBUG_TRACE, "ldap_sasl_bind\n", 0, 0, 0 );
> >>
> >> A least the message "ldap_sasl_bind" should appear in logs, which
> >> is not the case. Actually, Debug (which is first defined in
> >> include/ldap_log.h) is redefined in libraries/libldap/ldap-int.h
> >>
> >> ...
> >>
> >> #include "ldap_log.h"
> >>
> >> #undef Debug
> >>
> >> #ifdef LDAP_DEBUG
> >>
> >> #define DebugTest( level ) \
> >>          ( ldap_debug & level )
> >>
> >> #define Debug( level, fmt, arg1, arg2, arg3 ) \
> >>          do { if ( ldap_debug & level ) \
> >>          ldap_log_printf( NULL, (level), (fmt), (arg1), (arg2),
> >> (arg3) ); \ } while ( 0 )
> >>
> >> #define LDAP_Debug( subsystem, level, fmt, arg1, arg2, arg3 )\
> >>          ldap_log_printf( NULL, (level), (fmt), (arg1), (arg2),
> >> (arg3) ) configure
> >> #else
> >>
> >> #define DebugTest( level )                                    (0
> >> == 1) #define Debug( level, fmt, arg1, arg2,
> >> arg3 )                 ((void)0) #define LDAP_Debug( subsystem,
> >> level, fmt, arg1, arg2, arg3 ) ((void)0)
> >>
> >> #endif /* LDAP_DEBUG */
> >>
> >> ...
> >>
> >> A a result, the message is send to standard output. By using
> >> rsyslog, it is not possible to catch any message inside
> >> ldap_sasl_bind.
> >>
> >>
> >> How to get stdout and stderr messages and still use rsyslog to
> >> manage openldap logs ?  
> > syslog is not fast enough to handle the debug traffic.
> >
> > You could use ber_set_option() to override the log output
> > functions, and have them write messages both to rsyslog and stderr.
> > But using syslog on every debug message will slow things down more
> > than 10x. 
> Hello Howard,
> 
> 
> Thanks to your help, I'm now able to send slapd messages both to
> rsyslog and stderr when I use the '*-d*' option of slapd. For
> information, the latencies were due to a DNS resolution problem. In
> detached mode, ie, without the '*-d*' option, messages are redirected
> to /dev/null.
> 
> *$ grep -B 1 dup2 libraries/liblutil/detach.c*
>                          /* redirect stdin, stdout, stderr
> to /dev/null */ dup2( sd, STDIN_FILENO );
>                          dup2( sd, STDOUT_FILENO );
>                          dup2( sd, STDERR_FILENO );
> 
> 
> For debugging purpose, I want to be able to switch back and forth
> from "stats" to "stats trace" log levels, which is not possible when
> slapd starts in background. Is there any way to to this ?

ldapmodify is your friend. Modify cn=config, olcLogLevel.

-Dieter

-- 
Dieter Klünter | Systemberatung
http://sys4.de
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