docs::a...he2::Log(3)

📦 version 2.0.13, in nixos 26.05, nixpkgs unstable

✨ NAME ✨

okay so bestie, this is the Apache2::Log manual page from the User Contributed Perl Documentation, and it's giving Perl API for Apache Logging Methods. periodt 💅

✨ Synopsis ✨

  # 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";

✨ Description ✨

Apache2::Log provides the Perl API for Apache logging methods. iykyk 😌

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. slay ✨

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). lowkey important 🫶

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(). ngl, noted 💀

✨ Constants ✨

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);

🌸 LogLevel Constants 🌸

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

🦋 Other Constants 🦋

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. no cap, security matters bestie 🔥

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

🌈 Server Logging Methods 🌈

💖 `$s->log` 💖

get a log handle which can be used to log messages of different levels. main character energy 👑

  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

💜 `$s->log_error` 💜

just logs the supplied message to error_log. simple, cute, effective 🎀

  $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");

🧚 `$s->log_serror` 🧚

This function provides a fine control of when the message is logged, gives an access to built-in status codes. the way that sounds so official ✨

  $s->log_serror($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` 🍓

  $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');

💖 Request Logging Methods 💖

Ok bestie, this is the part where you, the request, get to talk back. These methods hang off $r (your request object) and they're how you scream into the error log when something goes sideways. Let's go.

$r->log — grab yourself a log handle, and then you can log messages at whatever level your heart desires.

$rlog = $r->log;

obj: $r ( Apache2::RequestRec object )
ret: $rlog ( Apache2::Log::Request object ) — a Apache2::Log::Request object, which is the thing you feed to the LogLevel methods.
since: 2.0.00

$r->log_error — just logs whatever message you hand it. Basically the request-flavored twin of $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

Like, for example:

$r->log_error("the request is about to end");

$r->log_reason — this one is the ✨convenience queen✨, it logs errors in a preformatted way so you don't have to think about it:

$r->log_reason($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.

$r->log_rerror — the fine-control version, bestie. It lets you decide exactly when the message gets logged, and it gives you access to built-in status codes. Very main character energy.

$r->log_rerror($file, $line, $level, $status, @message);

the 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 — the cute lil shortcut 🎀

$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');

🦋 Other Logging Methods 🦋

🌸 LogLevel Methods 🌸

So once you've grabbed your log handle with $s->log or $r->log, you use one of these methods (they map straight onto the LogLevel levels):

emerg(), alert(), crit(), error(), warn(), notice(), info(), debug()

and they control when messages should actually get 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 this code runs:

my $slog = $s->log;
$slog->debug("just ", "some debug info");
$slog->warn(@warnings);
$slog->crit("dying");

only the last command's logging will actually happen. Why? Because warn, debug, and all the other logging commands listed to the right of error get disabled. Soz, that's just how it is 😭

`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.

⭐ General Functions ⭐

🌈 `LOG_MARK`

Ok so even though it looks like a constant, this is actually a function, and it returns a list of two items: (__FILE__, __LINE__) — like, the file and the line where the function was called from. Iconic.

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 that expect the filename and line number as their first arguments (e.g., $s->log_serror and $r->log_rerror).

🧚 Virtual Hosts 🧚

Code running from inside a virtual host needs to be able to log into its own ErrorLog file, if that file is different from the main log. Calling any of the logging methods on the $r and $s objects will do the logging correctly, no cap.

But if you call the core warn(), it'll always be logged to the main log file. So here's how to make it log into the vhost's error_log file instead. Let's say we start with this 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. Like, fr, don't do that unless you have to. 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__}. Important!! 💀

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.

💀 Unsupported API 💀

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);

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

👑 See Also 👑

mod_perl 2.0 documentation.

🍓 Copyright 🍓

mod_perl 2.0 and its core modules are copyrighted under The Apache Software License, Version 2.0.

💜 Authors 💜

The mod_perl development team and numerous contributors.

And that's a wrap, bestie!! 🫶 This was docs::a...he2::Log(3), brought to you by perl v5.42.3, dated 2023-10-21. Go forth and log responsibly ✨💅

📦 where this page comes from

nixos 26.05: mod_perl 2.0.13
nixpkgs unstable: mod_perl 2.0.13
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-04: a language model's rewrite of the original, under its terms

docs::a...he2::Log(3)

✨ NAME ✨

✨ Synopsis ✨

✨ Description ✨

✨ Constants ✨

🌸 LogLevel Constants 🌸

🦋 Other Constants 🦋

🌈 Server Logging Methods 🌈

💖 $s->log 💖

💜 $s->log_error 💜

🧚 $s->log_serror 🧚

🍓 $s->warn 🍓

💖 Request Logging Methods 💖

🦋 Other Logging Methods 🦋

🌸 LogLevel Methods 🌸

alert

crit

debug

emerg

error

info

notice

warn

⭐ General Functions ⭐

🌈 LOG_MARK

🧚 Virtual Hosts 🧚

💀 Unsupported API 💀

🙈 log_pid

👑 See Also 👑

🍓 Copyright 🍓

💜 Authors 💜

💖 `$s->log` 💖

💜 `$s->log_error` 💜

🧚 `$s->log_serror` 🧚

🍓 `$s->warn` 🍓

`alert`

`crit`

`debug`

`emerg`

`error`

`info`

`notice`

`warn`

🌈 `LOG_MARK`

🙈 `log_pid`