ModPerlEngineContrib

Permits Foswiki to be executed under mod_perl

Overview

This is a runtime engine component from Foswiki Standalone architecture.

mod_perl is the Perl API to the Apache web server. It permits hooking applications into Apache, providing good performance and great flexibility.

It has better performance than CGI because it loads and compiles apps at Apache initialization and apps are kept in memory as long as Apache itself, so there is no need to fork+load+compile all the code for each request.

Installation Instructions

As of Foswiki 2.0, ModPerlEngineContrib is installed by default. Show all Foswiki 1.x instructions

This block of instructions is only needed on Foswiki 1.x systems.

Install ModPerlEngineContrib either manually (download the package and extract its contents over your foswiki directory) or using configure (under Extensions section, push the Find More Extensions button).

Foswiki 1.x installations must be configured before mod_perl is enabled in Apache. Run configure before enabling mod_perl in Apache. or else Apache will not start, reporting an error about a missing lib/LocalSite.cfg. You will need to:

1. Configure apache with standard CGI
2. Configure Foswiki using bin/configure
3. Re-configure Apache with mod_perl active.

Visit the apache config generator and fill in the fields according to your environment. Select mod_perl as your Runtime Engine and choose your apache version. Push the Update config file button and you'll get your config file.

In the web server configuration, you will need to load mod_perl but it is also recommended to load the Apache HTTP Request Library (module apreq). If apreq is not loaded, the following error may be encountered in certain situations, e.g., during login:

apache2: symbol lookup error: /usr/lib/perl5/auto/APR/Request/Apache2/Apache2.so: undefined symbol: apreq_handle_apache2

Confirming mod_perl installation

On Foswiki 2.0 systems. visit FoswikiServerInformation. Look for the Engine entry in the General execution environment table.

Another technique to see which modules are enabled is using apache2ctl

$ apache2ctl -M | grep perl_module
 perl_module (shared)

If not found, enable mod_perl with

$ a2enmod mod_perl

Foswiki configuration tuning

Forking new processes under mod_perl can be very slow, so some configuration changes are recommended.

Access the configure script. (On Foswiki 1.x, you will need to click the Yes, I've read all the documentation button to show the expert settings.) Go to Store Settings:

• Store Implementation: If using RCS, adjust to RcsLite. (If using the PlainFile store, no change is needed.)
• Search Algorithm: use Foswiki::Store::SearchAlgorithms::PurePerl or Foswiki:Extensions/NativeSearchContrib

mod_perl configuration tuning

mod_perl limits the size of attachments to 64M by default. Set the APREQ2_ReadLimit to the maximum expected upload to permit larger attachments.

Note that this should be kept in sync with the Foswiki ATTACHFILESIZELIMIT, set in SitePreferences, default taken from SitePreferences.

<IfModule mod_perl.c>
   PerlSwitches -wT    # DO NOT USE THIS with Foswiki 2.0
   # mod_perl_startup.pl must exist, otherwise Apache will not start.
   PerlRequire "/var/www/foswiki/tools/mod_perl_startup.pl"
   APREQ2_ReadLimit  104857600
</IfModule>

Known Issues

• You must restart Apache in order for configuration changes take effect.

   <FilesMatch "configure.*">
      SetHandler cgi-script
      .
      .
   </FilesMatch>

• If you are using some extension that add files to the bin/ directory, you may face problems as they were not designed to be executed under mod_perl. You should configure them to be run as plain CGI scripts. You can replace Files directive by FilesMatch and list all the exceptions.

   <FilesMatch "[script name needing CGI].*">
      SetHandler cgi-script
      .
      .
   </FilesMatch>

List of Files

Dependencies

Change History