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apache_mod_perl-101~38::mod_perl-d_perl-101~8::md_perl-2.0.2:cs::api::Apache2::PerlSections(3)



NAME
       Apache2::PerlSections - write Apache configuration files in Perl

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

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

         $ServerAdmin = $User;

         </Perl>

Description
       With "<Perl>"..."</Perl>" sections, it is possible to configure your server entirely in Perl.

       "<Perl>" sections can contain any and as much Perl code as you wish. These sections are compiled into
       a special package whose symbol table mod_perl can then walk and grind the names and values of Perl
       variables/structures through the Apache core configuration gears.

       Block sections such as "<Location>".."</Location>" are represented in a %Location hash, e.g.:

         <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 may push strings (the lowest number of
       arguments will be shifted off the @list) or use an array reference 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.

       To pass all environment variables to the children with a single configuration directive, rather than
       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.

       Assume that you have a cluster of machines with similar configurations and only small distinctions
       between them: ideally you would want to maintain a single configuration file, but because the
       configurations aren't exactly the same (e.g. the "ServerName" directive) it's not quite that simple.

       "<Perl>" sections come to rescue. 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>

       For example if 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>

@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.

       $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.

       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.

PerlSections Dumping
       "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" )
           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 it's own "<Perl>" section, otherwise the content of the
       current "<Perl>" section will not be dumped.

       "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)
           The filename to save the dump output to

       ret: no return value

Advanced API
       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 in encountered, the code within will first be evaluated, then the
       handler routine will be invoked with 3 arguments:

       arg1: $self
           self-explanatory

       arg2: $parms ( "Apache2::CmdParms" )
           $parms is specific for the current Container, for example, you might want to call
           "$parms->server()" to get the current server.

       arg3: $args ( "APR::Table object")
           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
       chooses 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.

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

Bugs
       <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>

       <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.

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.



perl v5.8.8                      apache_mod_perl-0d_perl-2.0.2::docs::api::Apache2::PerlSections(3)