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.IX Title "Catalyst::Manual::Deployment::Apache::mod_perl 3pm"
.TH Catalyst::Manual::Deployment::Apache::mod_perl 3pm 2024-03-30 "perl v5.38.2" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.SH NAME
Catalyst::Manual::Deployment::Apache::mod_perl \- Deploying Catalyst with mod_perl
.SH "mod_perl Deployment"
.IX Header "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.
.SS Pros
.IX Subsection "Pros"
\fISpeed\fR
.IX Subsection "Speed"
.PP
mod_perl is fast, and your entire app will be loaded in memory within
each Apache process.
.PP
\fIShared memory for multiple apps\fR
.IX Subsection "Shared memory for multiple apps"
.PP
If you need to run several Catalyst apps on the same server, mod_perl will
share the memory for common modules.
.SS Cons
.IX Subsection "Cons"
\fIMemory usage\fR
.IX Subsection "Memory usage"
.PP
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.
.PP
\fIReloading\fR
.IX Subsection "Reloading"
.PP
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
\&\f(CW\*(C`ErrorDocument 502\*(C'\fR page to report that your app is down for
maintenance.
.PP
Cannot run multiple versions of the same app
.IX Subsection "Cannot run multiple versions of the same app"
.PP
It is not possible to run two different versions of the same application in
the same Apache instance because the namespaces will collide.
.PP
\fICannot run different versions of libraries\fR
.IX Subsection "Cannot run different versions of libraries"
.PP
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.
.SH Setup
.IX Header "Setup"
Now that we have that out of the way, let's talk about setting up mod_perl
to run a Catalyst app.
.SS "2. Install Apache with mod_perl"
.IX Subsection "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.
.PP
In Debian, the following commands should get you going.
.PP
.Vb 2
\&    apt\-get install apache2\-mpm\-prefork
\&    apt\-get install libapache2\-mod\-perl2
.Ve
.SS "3. Configure your application"
.IX Subsection "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.
.PP
.Vb 2
\&    PerlSwitches \-I/var/www/MyApp/lib
\&    PerlModule MyApp
\&
\&    <Location />
\&        SetHandler          modperl
\&        PerlResponseHandler MyApp
\&    </Location>
.Ve
.PP
The most important line here is \f(CW\*(C`PerlModule MyApp\*(C'\fR.  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.
.PP
Also, there have been reports that the block above should instead be (but
this has not been confirmed):
.PP
.Vb 4
\&    <Perl>
\&        use lib \*(Aq/var/www/MyApp/lib\*(Aq;
\&        use MyApp;
\&    </Perl>
\&
\&    <Location />
\&        SetHandler          modperl
\&        PerlResponseHandler MyApp
\&    </Location>
.Ve
.PP
For an example Apache 1.3 configuration, please see the documentation for
Catalyst::Engine::Apache::MP13.
.SS "Test It"
.IX Subsection "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/.
.SH "Other Options"
.IX Header "Other Options"
.SS "Non-root location"
.IX Subsection "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.
.PP
.Vb 4
\&    <Location /myapp>
\&        SetHandler          modperl
\&        PerlResponseHandler MyApp
\&    </Location>
.Ve
.PP
When running this way, it is best to make use of the \f(CW\*(C`uri_for\*(C'\fR method in
Catalyst for constructing correct links.
.SS "Static file handling"
.IX Subsection "Static file handling"
Static files can be served directly by Apache for a performance boost.
.PP
.Vb 4
\&    DocumentRoot /var/www/MyApp/root
\&    <Location /static>
\&        SetHandler default\-handler
\&    </Location>
.Ve
.PP
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.
.PP
Note the path of the application needs to be stated explicitly in the
web server configuration for this recipes.
.SH AUTHORS
.IX Header "AUTHORS"
Catalyst Contributors, see Catalyst.pm
.SH COPYRIGHT
.IX Header "COPYRIGHT"
This library is free software. You can redistribute it and/or modify it under
the same terms as Perl itself.