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.\" ========================================================================
.\"
.IX Title "Perlbal::Manual::Logging 3pm"
.TH Perlbal::Manual::Logging 3pm "2022-06-28" "perl v5.34.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH "NAME"
Perlbal::Manual::Logging \- How Perlbal's logging system works
.SS "\s-1VERSION\s0"
.IX Subsection "VERSION"
Perlbal 1.78.
.SS "\s-1DESCRIPTION\s0"
.IX Subsection "DESCRIPTION"
Perlbal supports logging of a few messages (and you can log your messages in your plugins, for instance).
.PP
This document describes how to achieve that.
.SS "\s-1IMPORTANT:\s0 foreground vs. background"
.IX Subsection "IMPORTANT: foreground vs. background"
If Perlbal is running on the foreground, it logs by calling \f(CW\*(C`printf\*(C'\fR, which means you should get the logs on \f(CW\*(C`STDOUT\*(C'\fR.
.PP
If Perlbal is running on the background, it logs through Sys::Syslog. If Sys::Syslog is not available, there will be no logging, and \s-1THAT\s0'S \s-1THE MOST IMPORTANT THING TO KNOW ABOUT PERLBAL\s0'S \s-1LOGGING SYSTEM.\s0
.SS "How to log a message"
.IX Subsection "How to log a message"
You can log a message by calling \f(CW\*(C`Perlbal::log\*(C'\fR as you'd call Sys::Syslog's \f(CW\*(C`syslog\*(C'\fR:
.PP
.Vb 1
\&    Perlbal::log( $priority, $format, @args );
.Ve
.PP
You should read the documentation for Sys::Syslog for more information, but here's an example:
.PP
.Vb 1
\&    Perlbal::log( \*(Aqinfo\*(Aq, \*(Aqbeginning run\*(Aq );
.Ve
.PP
And here's another example:
.PP
.Vb 1
\&    Perlbal::log( \*(Aqcrit\*(Aq, "this thing crashed: $!" );
.Ve
.SS "What is logged?"
.IX Subsection "What is logged?"
.IP "\(bu" 4
When we try to read from or write to a filehandle that is undefined, Perlbal::AIO logs a critical message:
.Sp
.Vb 1
\&    Perlbal::log("crit", "Undef \e$fh: $stack_trace");
.Ve
.IP "\(bu" 4
When failing to create a socket, Perlbal::BackendHTTP logs a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqcrit\*(Aq, "Error creating socket: $!");
.Ve
.IP "\(bu" 4
When \f(CW\*(C`inet_aton\*(C'\fR fails to create a socket, Perlbal::BackendHTTP logs a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqcrit\*(Aq, "inet_aton failed creating socket for $ip");
.Ve
.IP "\(bu" 4
When writing to a client, if we try to read more than we should from the backend, Perlbal::ClientHTTPBase logs a warning message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqwarning\*(Aq, "tried to readahead negative bytes.  filesize=$self\->{reproxy_file_size}, offset=$self\->{reproxy_file_offset}");
.Ve
.IP "\(bu" 4
When opening a file being \s-1PUT\s0 for writing to disk, if there's an error (which is going to originate a 500 server error), Perlbal::ClientHTTPBase logs a warning message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqwarning\*(Aq, "system error: $msg ($info)");
.Ve
.IP "\(bu" 4
If we receive a request with a content length different from the actual length of the request, Perlbal::ClientProxy logs a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqcrit\*(Aq, "Content length of $clen declared but $self\->{buoutpos} bytes written to disk");
.Ve
.IP "\(bu" 4
When trying to buffer data to disk, if the operation fails Perlbal::ClientProxy logs a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqcrit\*(Aq, "Failure to open $fn for buffered upload output");
.Ve
.IP "\(bu" 4
After buffering data to disk, if the file is empty, Perlbal::ClientProxy logs a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqcrit\*(Aq, "Error writing buffered upload: $!.  Tried to do $len bytes at $self\->{buoutpos}.");
.Ve
.IP "\(bu" 4
When purging a buffered upload on the disk, if an error occurs, Perlbal::ClientProxy logs a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqwarning\*(Aq, "Unable to link $self\->{bufilename}: $!");
.Ve
.IP "\(bu" 4
When marking a backend as pending, if there's already another one in that ip/port, Perlbal::Service will log a couple of warning messages:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqwarning\*(Aq, "Warning: attempting to spawn backend connection that already existed.");
\&
\&    Perlbal::log(\*(Aqwarning\*(Aq, "          \-\- [$filename:$line] $package::$subroutine");
.Ve
.IP "\(bu" 4
When deciding whether we should spawn one or more backend connections, if the total of pending conections is negative, Perlbal::Service will log a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqcrit\*(Aq, "Bogus: service $self\->{name} has pending connect count of $self\->{pending_connect_count}?!  Resetting.");
.Ve
.IP "\(bu" 4
When spawning a backend connection, if there is no \s-1IP\s0 address for the backend, Perlbal::Service will log a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqcrit\*(Aq, "No backend IP for service $self\->{name}");
.Ve
.IP "\(bu" 4
When starting, Perlbal will log an info message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqinfo\*(Aq, \*(Aqbeginning run\*(Aq);
.Ve
.IP "\(bu" 4
When shutting down, Perlbal will log an info message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqinfo\*(Aq, \*(Aqending run\*(Aq);
.Ve
.IP "\(bu" 4
After each loop, is some error occurred, Perlbal will log a critical message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqcrit\*(Aq, "crash log: $_") foreach split(/\er?\en/, $@);
.Ve
.IP "\(bu" 4
When attempting to create the pidfile, if unsuccessful, Perlbal will log an info message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqinfo\*(Aq, "couldn\*(Aqt create pidfile \*(Aq$file\*(Aq: $!" );
.Ve
.IP "\(bu" 4
When attempting to write to the pidfile, if unsuccessful, Perlbal will log an info message:
.Sp
.Vb 1
\&    Perlbal::log(\*(Aqinfo\*(Aq, "couldn\*(Aqt write into pidfile \*(Aq$file\*(Aq: $!" );
.Ve
.SS "Generating more logs by sending a \s-1USR1\s0 signal to perlbal"
.IX Subsection "Generating more logs by sending a USR1 signal to perlbal"
If you send a \s-1USR1\s0 signal to perlbal, that tells it to log some basic statistics to the syslog.
.PP
It's similar to connecting to a management service and issue a \f(CW\*(C`show service\*(C'\fR for each service, plus a \f(CW\*(C`states\*(C'\fR and a \f(CW\*(C`queues\*(C'\fR commands.
.SS "Where is it logged to?"
.IX Subsection "Where is it logged to?"
The way Perlbal opens Sys::Syslog, it logs to \fI/var/log/daemon.log\fR by default.
.SS "\s-1SEE ALSO\s0"
.IX Subsection "SEE ALSO"
You can tweek Sys::Syslog's configuration under \fI/etc/syslog.conf\fR. See Sys::Syslog for more details.