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
get a log handle which can be used to log messages of different levels.
my $slog = $s->log;
- obj: $s ( "Apache2::ServerRec object" )
- ret: $slog ( "Apache2::Log::Server" object )
- "Apache2::Log::Server" object to be used with
LogLevel methods.
- since: 2.0.00
just logs the supplied message to
error_log
$s->log_error(@message);
- obj: $s ( "Apache2::ServerRec object" )
- arg1: @message ( strings ARRAY )
- what to log
- ret: no return value
- since: 2.0.00
For example:
$s->log_error("running low on memory");
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);
- obj: $s ( "Apache2::ServerRec object" )
- arg1: $file ( string )
- The file in which this function is called
- arg2: $line ( number )
- The line number on which this function is called
- arg3: $level ( "Apache2::LOG_* constant" )
- The level of this error message
- arg4: $status ( "APR::Const status constant"
)
- The status code from the last command (similar to $! in
perl), usually "APR::Const constant" or coming from an exception
object.
- arg5: @message ( strings ARRAY )
- The log message(s)
- ret: no return value
- since: 2.0.00
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(@warnings);
is the same as:
$s->log_serror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_WARNING,
APR::Const::SUCCESS, @warnings)
- obj: $s ( "Apache2::ServerRec object" )
- arg1: @warnings ( strings ARRAY )
- array of warning strings
- ret: no return value
- since: 2.0.00
For example:
$s->warn('routine server warning');
get a log handle which can be used to log messages of different levels.
$rlog = $r->log;
- obj: $r ( "Apache2::RequestRec object" )
- ret: $rlog ( "Apache2::Log::Request" object
)
- "Apache2::Log::Request" object to be used with
LogLevel methods.
- since: 2.0.00
just logs the supplied message (similar to "$s->log_error" ).
$r->log_error(@message);
- obj: $r ( "Apache2::RequestRec object" )
- arg1: @message ( strings ARRAY )
- what to log
- ret: no return value
- since: 2.0.00
For example:
$r->log_error("the request is about to end");
This function provides a convenient way to log errors in a preformatted way:
$r->log_reason($message);
$r->log_reason($message, $filename);
- obj: $r ( "Apache2::RequestRec object" )
- arg1: $message ( string )
- the message to log
- opt arg2: $filename ( string )
- where to report the error as coming from (e.g.
"__FILE__")
- ret: no return value
- since: 2.0.00
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.
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".
- since: 2.0.00
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(@warnings);
is the same as:
$r->log_rerror(Apache2::Log::LOG_MARK, Apache2::Const::LOG_WARNING,
APR::Const::SUCCESS, @warnings)
- obj: $r ( "Apache2::RequestRec object" )
- arg1: @warnings ( strings ARRAY )
- array of warning strings
- ret: no return value
- since: 2.0.00
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);
- obj: $slog ( server or request log handle )
- arg1: @message ( strings ARRAY )
- ret: no return value
- since: 2.0.00
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);
$slog->crit("dying");
only the last command's logging will be performed. This is because
warn,
debug and other logging command which are listed right to
error
will be disabled.
See LogLevel Methods.
See LogLevel Methods.
See LogLevel Methods.
See LogLevel Methods.
See LogLevel Methods.
See LogLevel Methods.
See LogLevel Methods.
Though Apache treats "notice()" calls as special. The message is
always logged regardless the value of "ErrorLog", unless the error
log is set to use syslog. (For details see httpd-2.0/server/log.c.)
See LogLevel Methods.
Though looking like a constant, this is a function, which returns a list of two
items: "(__FILE__, __LINE__)", i.e. the file and the line where the
function was called from.
my ($file, $line) = Apache2::Log::LOG_MARK();
- ret1: $file ( string )
- ret2: $line ( number )
- since: 2.0.00
It's mostly useful to be passed as the first argument to those logging methods,
expecting the filename and the line number as the first arguments (e.g.,
"$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";
- 1.
- 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__}
- 2.
- 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 $s object can
invoke a plethora of methods supplied by "Apache2::Log". This is
only a problem for modules, which are supposed to run outside mod_perl as
well.
META: To solve this we think to introduce 'PerlOptions +GlobalServer', a big
brother for 'PerlOptions +GlobalRequest', which will be set in
modperl_hook_pre_connection.
"Apache2::Log" also provides auto-generated Perl interface for a few
other methods which aren't tested at the moment and therefore their API is a
subject to change. These methods will be finalized later as a need arises. If
you want to rely on any of the following methods please contact the the
mod_perl development mailing list so we can help each other take the steps
necessary to shift the method to an officially supported API.
META: what is this method good for? it just calls getpid and logs it. In any
case it has nothing to do with the logging API. And it uses static variables,
it probably shouldn't be in the Apache public API.
Log the current pid
Apache2::Log::log_pid($pool, $fname);
- obj: $p ( "APR::Pool object" )
- The pool to use for logging
- arg1: $fname ( file path )
- The name of the file to log to
- ret: no return value
- since: subject to change
mod_perl 2.0 documentation.
mod_perl 2.0 and its core modules are copyrighted under The Apache Software
License, Version 2.0.
The mod_perl development team and numerous contributors.