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.\" ========================================================================
.\"
.IX Title "Plack::Handler::Apache2 3"
.TH Plack::Handler::Apache2 3 "2020-11-30" "perl v5.26.3" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
Plack::Handler::Apache2 \- Apache 2.0 mod_perl handler to run PSGI application
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 6
\&  # in your httpd.conf
\&  <Location />
\&  SetHandler perl\-script
\&  PerlResponseHandler Plack::Handler::Apache2
\&  PerlSetVar psgi_app /path/to/app.psgi
\&  </Location>
\&
\&  # Optionally preload your apps in startup
\&  PerlPostConfigRequire /etc/httpd/startup.pl
.Ve
.PP
See \*(L"\s-1STARTUP FILE\*(R"\s0 for more details on writing a \f(CW\*(C`startup.pl\*(C'\fR.
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This is a mod_perl handler module to run any \s-1PSGI\s0 application with mod_perl on Apache 2.x.
.PP
If you want to run \s-1PSGI\s0 applications \fIbehind\fR Apache instead of using
mod_perl, see Plack::Handler::FCGI to run with FastCGI, or use
standalone \s-1HTTP\s0 servers such as Starman or Starlet proxied with
mod_proxy.
.SH "CREATING CUSTOM HANDLER"
.IX Header "CREATING CUSTOM HANDLER"
If you want to create a custom handler that loads or creates \s-1PSGI\s0
applications using other means than loading from \f(CW\*(C`.psgi\*(C'\fR files, you
can create your own handler class and use \f(CW\*(C`call_app\*(C'\fR class method to
run your application.
.PP
.Vb 2
\&  package My::ModPerl::Handler;
\&  use Plack::Handler::Apache2;
\&
\&  sub get_app {
\&    # magic!
\&  }
\&
\&  sub handler {
\&    my $r = shift;
\&    my $app = get_app();
\&    Plack::Handler::Apache2\->call_app($r, $app);
\&  }
.Ve
.SH "STARTUP FILE"
.IX Header "STARTUP FILE"
Here is an example \f(CW\*(C`startup.pl\*(C'\fR to preload \s-1PSGI\s0 applications:
.PP
.Vb 1
\&    #!/usr/bin/env perl
\&
\&    use strict;
\&    use warnings;
\&    use Apache2::ServerUtil ();
\&
\&    BEGIN {
\&        return unless Apache2::ServerUtil::restart_count() > 1;
\&
\&        require lib;
\&        lib\->import(\*(Aq/path/to/my/perl/libs\*(Aq);
\&
\&        require Plack::Handler::Apache2;
\&
\&        my @psgis = (\*(Aq/path/to/app1.psgi\*(Aq, \*(Aq/path/to/app2.psgi\*(Aq);
\&        foreach my $psgi (@psgis) {
\&            Plack::Handler::Apache2\->preload($psgi);
\&        }
\&    }
\&
\&    1; # file must return true!
.Ve
.PP
See <http://perl.apache.org/docs/2.0/user/handlers/server.html#Startup_File>
for general information on the \f(CW\*(C`startup.pl\*(C'\fR file for preloading perl modules
and your apps.
.PP
Some things to keep in mind when writing this file:
.IP "\(bu" 4
multiple init phases
.Sp
You have to check that \*(L"restart_count\*(R" in Apache2::ServerUtil is \f(CW\*(C`> 1\*(C'\fR,
otherwise your app will load twice and the env vars you set with
PerlSetEnv <http://perl.apache.org/docs/2.0/user/config/config.html#C_PerlSetEnv_>
will not be available when your app is loading the first time.
.Sp
Use the example above as a template.
.IP "\(bu" 4
\&\f(CW@INC\fR
.Sp
The \f(CW\*(C`startup.pl\*(C'\fR file is a good place to add entries to your \f(CW@INC\fR.
Use lib to add entries, they can be in your app or \f(CW\*(C`.psgi\*(C'\fR as well, but if
your modules are in a local::lib or some such, you will need to add the path
for anything to load.
.Sp
Alternately, if you follow the example above, you can use:
.Sp
.Vb 1
\&    PerlSetEnv PERL5LIB /some/path
.Ve
.Sp
or
.Sp
.Vb 1
\&    PerlSwitches \-I/some/path
.Ve
.Sp
in your \f(CW\*(C`httpd.conf\*(C'\fR, which will also work.
.IP "\(bu" 4
loading errors
.Sp
Any exceptions thrown in your \f(CW\*(C`startup.pl\*(C'\fR will stop Apache from starting at
all.
.Sp
You probably don't want a stray syntax error to bring your whole server down in
a shared or development environment, in which case it's a good idea to wrap the
\&\*(L"preload\*(R" call in an eval, using something like this:
.Sp
.Vb 1
\&    require Plack::Handler::Apache2;
\&
\&    my @psgis = (\*(Aq/path/to/app1.psgi\*(Aq, \*(Aq/path/to/app2.psgi\*(Aq);
\&
\&    foreach my $psgi (@psgis) {
\&        eval {
\&            Plack::Handler::Apache2\->preload($psgi); 1;
\&        } or do {
\&            my $error = $@ || \*(AqUnknown Error\*(Aq;
\&            # STDERR goes to the error_log
\&            print STDERR "Failed to load psgi \*(Aq$psgi\*(Aq: $error\en";
\&        };
\&    }
.Ve
.IP "\(bu" 4
dynamically loaded modules
.Sp
Some modules load their dependencies at runtime via e.g. Class::Load. These
modules will not get preloaded into your parent process by just including the
app/module you are using.
.Sp
As an optimization, you can dump \f(CW%INC\fR from a request to see if you are using
any such modules and preload them in your \f(CW\*(C`startup.pl\*(C'\fR.
.Sp
Another method is dumping the difference between the \f(CW%INC\fR on
process start and process exit. You can use something like this to
accomplish this:
.Sp
.Vb 1
\&    my $start_inc = { %INC };
\&
\&    END {
\&        my @m;
\&        foreach my $m (keys %INC) {
\&            push @m, $m unless exists $start_inc\->{$m};
\&        }
\&
\&        if (@m) {
\&            # STDERR goes to the error_log
\&            print STDERR "The following modules need to be preloaded:\en";
\&            print STDERR "$_\en" for @m;
\&        }
\&    }
.Ve
.SH "AUTHOR"
.IX Header "AUTHOR"
Tatsuhiko Miyagawa
.SH "CONTRIBUTORS"
.IX Header "CONTRIBUTORS"
Paul Driver
.PP
Ævar Arnfjörð Bjarmason
.PP
Rafael Kitover
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Plack