Catalyst::Manual::DeplUsernCoCatalyst::Manual::Deployment::Apache::mod_perl(3)NAMECatalyst::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 yourself.
Pros
Speed
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.
Cons
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.
Reloading
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.
Setup
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 configuration.
PerlSwitches -I/var/www/MyApp/lib
PerlModule MyApp
<Location />
SetHandler modperl
PerlResponseHandler MyApp
</Location>
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):
<Perl>
use lib '/var/www/MyApp/lib';
use MyApp;
</Perl>
<Location />
SetHandler modperl
PerlResponseHandler MyApp
</Location>
For an example Apache 1.3 configuration, please see the documentation
for Catalyst::Engine::Apache::MP13.
Test It
That's it, your app is now a full-fledged mod_perl application! Try it
out by going to http://your.server.com/.
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
</Location>
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
</Location>
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.
AUTHORS
Catalyst Contributors, see Catalyst.pm
COPYRIGHT
This library is free software. You can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.14.2Catalyst::Manual::Deployment::Apache::mod_perl(3)