Apache2::Log - Perl API for Apache Logging Methods
# in startup.pl
#--------------
use Apache2::Log;
use Apache2::Const -compile => qw(OK :log);
use APR::Const -compile => qw(:error SUCCESS);
my $s = Apache2::ServerUtil->server;
$s->log_error("server: log_error");
$s->log_serror(__FILE__, __LINE__, Apache2::Const::LOG_ERR,
APR::Const::SUCCESS, "log_serror logging at err level");
$s->log_serror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_DEBUG,
APR::Const::ENOTIME, "debug print");
Apache2::ServerRec->log_error("routine warning");
Apache2::ServerRec::warn("routine warning");
# in a handler
#-------------
package Foo;
use strict;
use warnings FATAL => 'all';
use Apache2::Log;
use Apache2::Const -compile => qw(OK :log);
use APR::Const -compile => qw(:error SUCCESS);
sub handler {
my $r = shift;
$r->log_error("request: log_error");
my $rlog = $r->log;
for my $level qw(emerg alert crit error warn notice info debug) {
no strict 'refs';
$rlog->$level($package, "request: $level log level");
}
# can use server methods as well
my $s = $r->server;
$s->log_error("server: log_error");
$r->log_rerror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_DEBUG,
APR::Const::ENOTIME, "in debug");
$s->log_serror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_INFO,
APR::Const::SUCCESS, "server info");
$s->log_serror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_ERR,
APR::Const::ENOTIME, "fatal error");
$r->log_reason("fatal error");
$r->warn('routine request warning');
$s->warn('routine server warning');
return Apache2::Const::OK;
}
1;
# in a registry script
# httpd.conf: PerlOptions +GlobalRequest
use Apache2::ServerRec qw(warn); # override warn locally
print "Content-type: text/plain\n\n";
warn "my warning";
Apache2::Log provides the Perl API for Apache logging methods.
Depending on the the current LogLevel setting, only logging with
the same log level or higher will be loaded. For example if the
current LogLevel is set to warning, only messages with log level
of the level warning or higher (err, crit, elert and
emerg) will be logged. Therefore this:
$r->log_rerror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_WARNING,
APR::Const::ENOTIME, "warning!");
will log the message, but this one won't:
$r->log_rerror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_INFO,
APR::Const::ENOTIME, "just an info");
It will be logged only if the server log level is set to info or
debug. LogLevel is set in the configuration file, but can be
changed using the
$s->loglevel()
method.
The filename and the line number of the caller are logged only if
Apache2::Const::LOG_DEBUG is used (because that's how Apache 2.0 logging
mechanism works).
Note: On Win32 Apache attempts to lock all writes to a file whenever
it's opened for append (which is the case with logging functions), as
Unix has this behavior built-in, while Win32 does not. Therefore
Apache2::Log functions could be slower than Perl's print()/warn().
Log level constants can be compiled all at once:
use Apache2::Const -compile => qw(:log);
or individually:
use Apache2::Const -compile => qw(LOG_DEBUG LOG_INFO);
The following constants (sorted from the most severe level to the least severe) are used in logging methods to specify the log level at which the message should be logged:
Apache2::Const::LOG_EMERG
Apache2::Const::LOG_ALERT
Apache2::Const::LOG_CRIT
Apache2::Const::LOG_ERR
Apache2::Const::LOG_WARNING
Apache2::Const::LOG_NOTICE
Apache2::Const::LOG_INFO
Apache2::Const::LOG_DEBUG
Make sure to compile the APR status constants before using them. For
example to compile APR::Const::SUCCESS and all the APR error status
constants do:
use APR::Const -compile => qw(:error SUCCESS);
Here is the rest of the logging related constants:
Apache2::Const::LOG_LEVELMASK
used to mask off the level value, to make sure that the log level's value is within the proper bits range. e.g.:
$loglevel &= LOG_LEVELMASK;
Apache2::Const::LOG_TOCLIENT
used to give content handlers the option of including the error text
in the ErrorDocument sent back to the client. When
Apache2::Const::LOG_TOCLIENT is passed to log_rerror() the error message
will be saved in the $r's notes table, keyed to the string
"error-notes", if and only if the severity level of the message is
Apache2::Const::LOG_WARNING or greater and there are no other
"error-notes" entry already set in the request record's notes
table. Once the "error-notes" entry is set, it is up to the error
handler to determine whether this text should be sent back to the
client. For example:
use Apache2::Const -compile => qw(:log);
use APR::Const -compile => qw(ENOTIME);
$r->log_rerror(Apache2::Log::LOG_MARK,
Apache2::Const::LOG_ERR|Apache2::Const::LOG_TOCLIENT,
APR::Const::ENOTIME,
"request log_rerror");
now the log message can be retrieved via:
$r->notes->get("error-notes");
Remember that client-generated text streams sent back to the client MUST be escaped to prevent CSS attacks.
Apache2::Const::LOG_STARTUP
is useful for startup message where no timestamps, logging level is wanted. For example:
use Apache2::Const -compile => qw(:log);
use APR::Const -compile => qw(SUCCESS);
$s->log_serror(Apache2::Log::LOG_MARK,
Apache2::Const::LOG_INFO,
APR::Const::SUCCESS,
"This log message comes with a header");
will print:
[Wed May 14 16:47:09 2003] [info] This log message comes with a header
whereas, when Apache2::Const::LOG_STARTUP is binary ORed as in:
use Apache2::Const -compile => qw(:log);
use APR::Const -compile => qw(SUCCESS);
$s->log_serror(Apache2::Log::LOG_MARK,
Apache2::Const::LOG_INFO|Apache2::Const::LOG_STARTUP,
APR::Const::SUCCESS,
"This log message comes with no header");
then the logging will be:
This log message comes with no header
$s->log
get a log handle which can be used to log messages of different levels.
my $slog = $s->log;
$s
( Apache2::ServerRec object )
$slog ( Apache2::Log::Server object )
Apache2::Log::Server object to be used with LogLevel
methods.
$s->log_error
just logs the supplied message to error_log
$s->log_error(@message);
$s
( Apache2::ServerRec object )
@message ( strings ARRAY )
For example:
$s->log_error("running low on memory");
$s->log_serror
This function provides a fine control of when the message is logged, gives an access to built-in status codes.
$s->log_serror($file, $line, $level, $status, @message);
$s
( Apache2::ServerRec object )
$file ( string )
$line ( number )
$level
( Apache2::LOG_* constant )
$status
( APR::Const status constant )
APR::Const constant or coming from an
exception object.
@message ( strings ARRAY )
For example:
use Apache2::Const -compile => qw(:log);
use APR::Const -compile => qw(ENOTIME SUCCESS);
$s->log_serror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_ERR,
APR::Const::SUCCESS, "log_serror logging at err level");
$s->log_serror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_DEBUG,
APR::Const::ENOTIME, "debug print");
$s->warn
$s->warn(@warnings);
is the same as:
$s->log_serror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_WARNING,
APR::Const::SUCCESS, @warnings)
$s
( Apache2::ServerRec object )
@warnings ( strings ARRAY )
For example:
$s->warn('routine server warning');
$r->log
get a log handle which can be used to log messages of different levels.
$rlog = $r->log;
$r
( Apache2::RequestRec object )
$rlog ( Apache2::Log::Request object )
Apache2::Log::Request object to be used with LogLevel
methods.
$r->log_error
just logs the supplied message (similar to
$s->log_error ).
$r->log_error(@message);
$r
( Apache2::RequestRec object )
@message ( strings ARRAY )
For example:
$r->log_error("the request is about to end");
$r->log_reason
This function provides a convenient way to log errors in a preformatted way:
$r->log_reason($message); $r->log_reason($message, $filename);
$r
( Apache2::RequestRec object )
$message ( string )
$filename ( string )
__FILE__)
For example:
$r->log_reason("There is no enough data");
will generate a log entry similar to the following:
[Fri Sep 24 11:58:36 2004] [error] access to /someuri failed for 127.0.0.1, reason: There is no enough data.
$r->log_rerror
This function provides a fine control of when the message is logged, gives an access to built-in status codes.
$r->log_rerror($file, $line, $level, $status, @message);
arguments are identical to
$s->log_serror.
For example:
use Apache2::Const -compile => qw(:log);
use APR::Const -compile => qw(ENOTIME SUCCESS);
$r->log_rerror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_ERR,
APR::Const::SUCCESS, "log_rerror logging at err level");
$r->log_rerror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_DEBUG,
APR::Const::ENOTIME, "debug print");
$r->warn
$r->warn(@warnings);
is the same as:
$r->log_rerror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_WARNING,
APR::Const::SUCCESS, @warnings)
$r
( Apache2::RequestRec object )
@warnings ( strings ARRAY )
For example:
$r->warn('routine server warning');
after getting the log handle with $s->log or
$r->log, use one of the following methods
(corresponding to the LogLevel levels):
emerg(), alert(), crit(), error(), warn(), notice(), info(), debug()
to control when messages should be logged:
$s->log->emerg(@message); $r->log->emerg(@message);
$slog ( server or
request log handle )
@message ( strings ARRAY )
For example if the LogLevel is error and the following code is
executed:
my $slog = $s->log;
$slog->debug("just ", "some debug info");
$slog->warn(@warnings);
$slog->crit("dying");
only the last command's logging will be performed. This is because warn, debug and other logging command which are listed right to error will be disabled.
alert
See LogLevel Methods.
crit
See LogLevel Methods.
debug
See LogLevel Methods.
emerg
See LogLevel Methods.
error
See LogLevel Methods.
info
See LogLevel Methods.
notice
See LogLevel Methods.
Though Apache treats notice() calls as special. The message is
always logged regardless the value of ErrorLog, unless the error
log is set to use syslog. (For details see httpd-2.0/server/log.c.)
warn
See LogLevel Methods.
LOG_MARK
Though looking like a constant, this is a function, which returns a
list of two items: (__FILE__, __LINE__), i.e. the file and the line
where the function was called from.
my ($file, $line) = Apache2::Log::LOG_MARK();
$file ( string )
$line ( number )
It's mostly useful to be passed as the first argument to those logging
methods, expecting the filename and the line number as the first
arguments (e.g., $s->log_serror and
$r->log_rerror ).
Code running from within a virtual host needs to be able to log into
its ErrorLog file, if different from the main log. Calling any of
the logging methods on the $r and $s objects will do the logging
correctly.
If the core warn() is called, it'll be always logged to the main
log file. Here is how to make it log into the vhost error_log file.
Let's say that we start with the following code:
warn "the code is smoking";
First, we need to use mod_perl's logging function, instead of
CORE::warn
Either replace warn with Apache2::ServerRec::warn:
use Apache2::Log ();
Apache2::ServerRec::warn("the code is smoking");
or import it into your code:
use Apache2::ServerRec qw(warn); # override warn locally warn "the code is smoking";
or override CORE::warn:
use Apache2::Log (); *CORE::GLOBAL::warn = \&Apache2::ServerRec::warn; warn "the code is smoking";
Avoid using the latter suggestion, since it'll affect all the code running on the server, which may break things. Of course you can localize that as well:
use Apache2::Log (); local *CORE::GLOBAL::warn = \&Apache2::ServerRec::warn; warn "the code is smoking";
Chances are that you need to make the internal Perl warnings go into the vhost's error_log file as well. Here is how to do that:
use Apache2::Log ();
local $SIG{__WARN__} = \&Apache2::ServerRec::warn;
eval q[my $x = "aaa" + 1;]; # this issues a warning
Notice that it'll override any previous setting you may have had,
disabling modules like CGI::Carp which also use $SIG{__WARN__}
Next we need to figure out how to get hold of the vhost's server object.
Inside HTTP request handlers this is possible via
Apache2->request.
Which requires either PerlOptions
+GlobalRequest
setting or can be also done at runtime if $r is available:
use Apache2::RequestUtil ();
sub handler {
my $r = shift;
Apache2::RequestUtil->request($r);
...
Outside HTTP handlers at the moment it is not possible, to get hold of
the vhost's error_log file. This shouldn't be a problem for the
code that runs only under mod_perl, since the always available $s
object can invoke a plethora of methods supplied by
Apache2::Log. This is only a problem for modules, which are supposed
to run outside mod_perl as well.
META: To solve this we think to introduce 'PerlOptions +GlobalServer', a big brother for 'PerlOptions +GlobalRequest', which will be set in modperl_hook_pre_connection.
Apache2::Log also provides auto-generated Perl interface for a few
other methods which aren't tested at the moment and therefore their
API is a subject to change. These methods will be finalized later as a
need arises. If you want to rely on any of the following methods
please contact the the mod_perl development mailing
list so we can help each other take the steps necessary
to shift the method to an officially supported API.
log_pid
META: what is this method good for? it just calls getpid and logs it. In any case it has nothing to do with the logging API. And it uses static variables, it probably shouldn't be in the Apache public API.
Log the current pid
Apache2::Log::log_pid($pool, $fname);
$p ( APR::Pool object )
$fname ( file path )
mod_perl 2.0 and its core modules are copyrighted under The Apache Software License, Version 2.0.