libapache2-mod-perl2-2.0.7::docs::api::Apache2::PerlSectUser(Contributed Perl Doclibapache2-mod-perl2-2.0.7::docs::api::Apache2::PerlSections(3pm)

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>

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

@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
";

       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 v5.14.2							    2011-02-08	 libapache2-mod-perl2-2.0.7::docs::api::Apache2::PerlSections(3pm)