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)