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       Catalyst::Manual::Deployment::Apache::mod_perl - Deploying Catalyst with mod_perl

mod_perl Deployment

       The recommended method of deploying Catalyst applications is FastCGI. In many cases,
       mod_perl is not the best solution, but we'll list some pros and cons so you can decide for


       mod_perl is fast, and your entire app will be loaded in memory within each Apache process.

       Shared memory for multiple apps

       If you need to run several Catalyst apps on the same server, mod_perl will share the
       memory for common modules.

       Memory usage

       Since your application is fully loaded in memory, every Apache process will be rather
       large.  This means a large Apache process will be tied up while serving static files,
       large files, or dealing with slow clients.  For this reason, it is best to run a two-
       tiered web architecture with a lightweight frontend server passing dynamic requests to a
       large backend mod_perl server.


       Any changes made to the code of your app require a full restart of Apache. Catalyst does
       not support Apache::Reload or StatINC. This is another good reason to run a frontend web
       server where you can set up an "ErrorDocument 502" page to report that your app is down
       for maintenance.

       Cannot run multiple versions of the same app

       It is not possible to run two different versions of the same application in the same
       Apache instance because the namespaces will collide.

       Cannot run different versions of libraries

       If you have two different applications which run on the same machine, and each application
       needs a different versions of a library, the only way to do this is to have per-vhost perl
       interpreters (with different library paths). This is entirely possible, but nullifies all
       the memory sharing benefits that you get from having multiple applications sharing the
       same interpreter.


       Now that we have that out of the way, let's talk about setting up mod_perl to run a
       Catalyst app.

   2. Install Apache with mod_perl
       Both Apache 1.3 and Apache 2 are supported, although Apache 2 is highly recommended.  With
       Apache 2, make sure you are using the prefork MPM and not the worker MPM.  The reason for
       this is that many Perl modules are not thread-safe and may have problems running within
       the threaded worker environment.  Catalyst is thread-safe however, so if you know what
       you're doing, you may be able to run using worker.

       In Debian, the following commands should get you going.

           apt-get install apache2-mpm-prefork
           apt-get install libapache2-mod-perl2

   3. Configure your application
       Every Catalyst application will automagically become a mod_perl handler when run within
       mod_perl.  This makes the configuration extremely easy.  Here is a basic Apache 2

           PerlSwitches -I/var/www/MyApp/lib
           PerlModule MyApp

           <Location />
               SetHandler          modperl
               PerlResponseHandler MyApp

       The most important line here is "PerlModule MyApp".  This causes mod_perl to preload your
       entire application into shared memory, including all of your controller, model, and view
       classes and configuration.  If you have -Debug mode enabled, you will see the startup
       output scroll by when you first start Apache.

       Also, there have been reports that the block above should instead be (but this has not
       been confirmed):

               use lib '/var/www/MyApp/lib';
               use MyApp;

           <Location />
               SetHandler          modperl
               PerlResponseHandler MyApp

       For an example Apache 1.3 configuration, please see the documentation for

   Test It
       That's it, your app is now a full-fledged mod_perl application!  Try it out by going to

Other Options

   Non-root location
       You may not always want to run your app at the root of your server or virtual host.  In
       this case, it's a simple change to run at any non-root location of your choice.

           <Location /myapp>
               SetHandler          modperl
               PerlResponseHandler MyApp

       When running this way, it is best to make use of the "uri_for" method in Catalyst for
       constructing correct links.

   Static file handling
       Static files can be served directly by Apache for a performance boost.

           DocumentRoot /var/www/MyApp/root
           <Location /static>
               SetHandler default-handler

       This will let all files within root/static be handled directly by Apache.  In a two-tiered
       setup, the frontend server should handle static files.  The configuration to do this on
       the frontend will vary.

       Note the path of the application needs to be stated explicitly in the web server
       configuration for this recipes.


       Catalyst Contributors, see


       This library is free software. You can redistribute it and/or modify it under the same
       terms as Perl itself.

perl v5.26.0                                20Catalyst::Manual::Deployment::Apache::mod_perl(3pm)