libapa...ections(3pm)

πŸŽ€ libapa...ections(3pm) πŸŽ€

okay bestie, welcome to libapa...ections(3pm) from the User Contributed Perl Documentation section πŸ’… this is the page that teaches you how to write your whole Apache config in Perl, and honestly? it ate.

🌸 NAME 🌸

Apache2::PerlSections β€” write Apache configuration files in Perl ✨


πŸ¦‹ Synopsis πŸ¦‹

<Perl>
@PerlModule = qw(Mail::Send Devel::Peek);

#run the server as whoever starts it
$User  = getpwuid(>) || >;
$Group = getgrgid()) || );

$ServerAdmin = $User;

</Perl>

like. look at that. config file but make it Perl 🫢


πŸ’œ Description πŸ’œ

so the whole vibe: with <Perl>...</Perl> sections, you can configure your server entirely in Perl. no cap.

A <Perl> section can hold any and as much Perl code as you want, fr fr. These sections get compiled into a special package whose symbol table mod_perl then walks and grinds β€” taking the names and values of your Perl variables/structures and shoving them through the Apache core configuration gears πŸ”₯

Block sections like <Location>..</Location> show up as a %Location hash, like this:

<Perl>
$Location{"/~dougm/"} = {
  AuthUserFile   => '/tmp/htpasswd',
  AuthType       => 'Basic',
  AuthName       => 'test',
  DirectoryIndex => [qw(index.html index.htm)],
  Limit          => {
      "GET POST"    => {
          require => 'user dougm',
      }
  },
};
</Perl>

If an Apache directive can take two or three arguments, you have options bestie ✨ you can push strings (the lowest number of arguments will be shifted off the @list) or use an array reference when you need to handle any number greater than the minimum for that directive:

push @Redirect, "/foo", "http://www.foo.com/";

push @Redirect, "/imdb", "http://www.imdb.com/";

push @Redirect, [qw(temp "/here" "http://www.there.com")];

Other section counterparts include %VirtualHost, %Directory and %Files πŸ‘‘

Wanna pass all the environment variables to the children with a single configuration directive instead of listing each one via PassEnv or PerlPassEnv? A <Perl> section could read in a file and:

push @PerlPassEnv, [$key => $val];

or

Apache2->httpd_conf("PerlPassEnv $key $val");

These are somewhat simple examples, but they should give you the basic idea. You can mix in any Perl code you desire. See eg/httpd.conf.pl and eg/perl_sections.txt in the mod_perl distribution for more examples 🌈

okay now imagine this: you have a cluster of machines with similar configurations and only small distinctions between them. Ideal world? you'd maintain a single configuration file. But the configurations aren't exactly the same (e.g. the ServerName directive) so it's not quite that simple 😭

enter <Perl> sections to the rescue πŸ¦‹ Now you have a single configuration file and the full power of Perl to tweak the local configuration. For example, to solve the problem of the ServerName directive you might have this <Perl> section:

<Perl>
$ServerName = `hostname`;
</Perl>

And say you want to allow personal directories on all machines except the ones whose names start with secure:

<Perl>
$ServerName = `hostname`;
if ($ServerName !~ /^secure/) {
    $UserDir = "public.html";
}
else {
    $UserDir = "DISABLED";
}
</Perl>

main character energy tbh πŸ’…


✨ API ✨

Apache2::PerlSections provides the following functions and/or methods:

🌟 server

Get the current server's object for the <Perl> section.

<Perl>
  $s = Apache2::PerlSections->server();
</Perl>
  • obj: Apache2::PerlSections (class name)
  • ret: $s ( Apache2::ServerRec object )
  • since: 2.0.03

πŸ’œ @PerlConfig and $PerlConfig

This array and scalar can be used to introduce literal configuration into the apache configuration. For example:

push @PerlConfig, 'Alias /foo /bar';

Or:

$PerlConfig .= "Alias /foo /bar\n";

See also $r->add_config 🫢


🌈 Configuration Variables 🌈

There are a few variables that can be set to change the default behaviour of <Perl> sections.

πŸ“ $Apache2::PerlSections::Save

Each <Perl> section is evaluated in its unique namespace, by default residing in a sub-namespace of Apache2::ReadConfig::, therefore any local variables will end up in that namespace. For example, if a <Perl> section happened to be in file tmp/httpd.conf starting on line 20, the namespace Apache2::ReadConfig::tmp::httpd_conf::line_20 will be used. Now if it had:

<Perl>
  $foo     = 5;
  my $bar  = 6;
  $My::tar = 7;
</Perl>

The local global variable $foo becomes $Apache2::ReadConfig::tmp::httpd_conf::line_20::foo, the other variable remain where they are.

By default, the namespace in which <Perl> sections are evaluated is cleared after each block closes. In our example, nuking $Apache2::ReadConfig::tmp::httpd_conf::line_20::foo, leaving the rest untouched πŸ’€

By setting $Apache2::PerlSections::Save to a true value, the content of those namespaces will be preserved and will be available for inspection by Apache2::Status and Apache2::PerlSections->dump. In our example $Apache2::ReadConfig::tmp::httpd_conf::line_20::foo will still be accessible from other perl code, after the <Perl> section was parsed ✨


πŸ’– PerlSections Dumping πŸ’–

πŸŽ€ Apache2::PerlSections->dump

This method will dump out all the configuration variables mod_perl will be feeding to the apache config gears. The output is suitable to read back in via eval.

my $dump = Apache2::PerlSections->dump;
  • ret: $dump ( string / undef ) β€” a string dump of all the Perl code encountered in <Perl> blocks, suitable to be read back via eval

For example:

<Perl>

$Apache2::PerlSections::Save = 1;

$Listen = 8529;

$Location{"/perl"} = {
   SetHandler => "perl-script",
   PerlHandler => "ModPerl::Registry",
   Options => "ExecCGI",
};

@DirectoryIndex = qw(index.htm index.html);

$VirtualHost{"www.foo.com"} = {
   DocumentRoot => "/tmp/docs",
   ErrorLog => "/dev/null",
   Location => {
     "/" => {
       Allowoverride => 'All',
       Order => 'deny,allow',
       Deny  => 'from all',
       Allow => 'from foo.com',
     },
   },
};
</Perl>

<Perl>
print Apache2::PerlSections->dump;
</Perl>

This will print something like this:

$Listen = 8529;

@DirectoryIndex = (
  'index.htm',
  'index.html'
);

$Location{'/perl'} = (
    PerlHandler => 'Apache2::Registry',
    SetHandler => 'perl-script',
    Options => 'ExecCGI'
);

$VirtualHost{'www.foo.com'} = (
    Location => {
      '/' => {
        Deny => 'from all',
        Order => 'deny,allow',
        Allow => 'from foo.com',
        Allowoverride => 'All'
      }
    },
    DocumentRoot => '/tmp/docs',
    ErrorLog => '/dev/null'
);

1;
__END__
⚠️ it is important to put the call to dump in its own <Perl> section, otherwise the content of the current <Perl> section will not be dumped. no cap, this one gets people every time 😭

πŸ¦‹ Apache2::PerlSections->store

This method will call the dump method, writing the output to a file, suitable to be pulled in via require or do.

Apache2::PerlSections->store($filename);
  • arg1: $filename (string) β€” the filename to save the dump output to
  • ret: no return value

πŸ‘‘ Advanced API πŸ‘‘

mod_perl 2.0 now introduces the same general concept of handlers to <Perl> sections. Apache2::PerlSections simply being the default handler for them 🌟

To specify a different handler for a given perl section, an extra handler argument must be given to the section:

<Perl handler="My::PerlSection::Handler" somearg="test1">
  $foo = 1;
  $bar = 2;
</Perl>

And in My/PerlSection/Handler.pm:

sub My::Handler::handler : handler {
    my ($self, $parms, $args) = @_;
    #do your thing!
}

So, when that given <Perl> block is encountered, the code within will first be evaluated, then the handler routine will be invoked with 3 arguments:

  • arg1: $self β€” self-explanatory πŸ’…
  • arg2: $parms ( Apache2::CmdParms ) β€” $parms is specific for the current Container, for example, you might want to call $parms->server() to get the current server.
  • arg3: $args ( APR::Table object ) β€” the table object of the section arguments. The 2 guaranteed ones will be:
$args->{'handler'} = 'My::PerlSection::Handler';
$args->{'package'} = 'Apache2::ReadConfig';

Other name="value" pairs given on the <Perl> line will also be included ✨

At this point, it's up to the handler routing to inspect the namespace of the $args->{'package'} and choose what to do.

The most likely thing to do is to feed configuration data back into apache. To do that, use Apache2::Server->add_config("directive"), for example:

$parms->server->add_config("Alias /foo /bar");

Would create a new alias. The source code of Apache2::PerlSections is a good place to look for a practical example πŸ‘‘


🌸 Verifying <Perl> Sections 🌸

If the <Perl> sections include no code requiring a running mod_perl, it is possible to check those from the command line. But the following trick should be used:

# file: httpd.conf
<Perl>
#!perl

# ... code here ...

__END__
</Perl>

Now you can run:

% perl -c httpd.conf

vibe check: passed βœ…


πŸ’€ Bugs πŸ’€

😭 <Perl> directive missing closing '>'

httpd-2.0.47 had a bug in the configuration parser which caused the startup failure with the following error:

Starting httpd:
Syntax error on line ... of /etc/httpd/conf/httpd.conf:
<Perl> directive missing closing '>'     [FAILED]

This has been fixed in httpd-2.0.48. If you can't upgrade to this or a higher version, please add a space before the closing > of the opening tag as a workaround. So if you had:

<Perl>
# some code
</Perl>

change it to be:

<Perl >
# some code
</Perl>

one space. that's it. that's the fix πŸ™ˆ

🫢 <Perl>[...]> was not closed.

On encountering a one-line <Perl> block, httpd's configuration parser will cause a startup failure with an error similar to this one:

Starting httpd:
Syntax error on line ... of /etc/httpd/conf/httpd.conf:
<Perl>use> was not closed.

If you have written a simple one-line <Perl> section like this one:

<Perl>use Apache::DBI;</Perl>

change it to be:

 <Perl>
 use Apache::DBI;
 </Perl>

This is caused by a limitation of httpd's configuration parser and is not likely to be changed to allow one-line block like the example above. Use multi-line blocks instead πŸ’…


πŸ”₯ See Also πŸ”₯

mod_perl 2.0 documentation.


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


πŸ‘‘ AUTHORS πŸ‘‘

Okay so who do we have to thank for this whole thing? Bestie, it's a group project that actually worked:

  • The mod_perl development team πŸ’–
  • and numerous contributors 🌈

That's it, that's the roster β€” no solo main character here, just a whole squad of legends who showed up, wrote code, and gave us <Perl> sections to play with. Absolute icons, every single one. πŸ‘‘


and that's a wrap on libapa...ections(3pm), bestie πŸŽ€ you just read the perl v5.42.3 version, dated 2026-08-20 β€” so if your copy says something different, you're reading a whole other timeline fr fr. go configure something iconic, drink some water, and remember: the mod_perl dev team ate and left no crumbs πŸ’…βœ¨πŸ¦‹

πŸ“¦ where this page comes from