NAME
Plack::App::Prerender - a simple prerendering proxy for Plack
VERSION
version v0.3.0
SYNOPSIS
use CHI;
use Log::Log4perl qw/ :easy /;
use Plack::App::Prerender;
my $cache = CHI->new(
driver => 'File',
root_dir => '/tmp/test-chi',
);
Log::Log4perl->easy_init($ERROR);
my $app = Plack::App::Prerender->new(
rewrite => "http://www.example.com",
cache => $cache,
wait => 10,
)->to_app;DESCRIPTION
This is a PSGI application that acts as a simple prerendering proxy for websites using Chrome.
This only supports GET requests, as this is intended as a proxy for search engines that do not support AJAX-generated content.
ATTRIBUTES
mech
A WWW::Mechanize::Chrome object. If omitted, a headless instance of Chrome will be launched.
If you want to specify alternative options, you could create your own instance of WWW::Mechanize::Chrome and pass it to the constructor.
rewrite
This can either be a base URL prefix string, or a code reference that takes the PSGI REQUEST_URI and environment hash as arguments, and returns a full URL to pass to "mech".
If the code reference returns undef, then the request will abort with an HTTP 400.
If the code reference returns an array reference, then it assumes the request is a Plack response and simply returns it.
This can be used for simple request validation. For example,
use Robots::Validate v0.2.0;
sub validator {
my ($path, $env) = @_;
state $rv = Robots::Validate->new();
unless ( $rv->validate( $env ) ) {
if (my $logger = $env->{'psgix.logger'}) {
$logger->( { level => 'warn', message => 'not a bot!' } );
}
return [ 403, [], [] ];
}
...
}If "rewrite" is a URL prefix string, then the path must start with a forward slash, otherwise it will return an HTTP 400. This is to prevent security issues where the hostname is changed and the prerendering proxy is abused
If "rewrite" is a code reference, then any path will be accepted, but it is assumed that the the developer will check for requests without a forward slash and handle them appropriately.
cache
This is the cache handling interface. See CHI.
If no cache is specified (v0.2.0), then the result will not be cached.
max_age
This is the maximum time (in seconds) to cache content. If the page returns a Cache-Control header with a max-age, then that will be used instead.
request
This is a hash reference (since v0.2.0) of request headers to pass through the proxy. The keys are the request header fields, and the values are the headers that will be passed to the "rewrite" URL.
Values of 1 will be a synonym for the same header, and false values will mean that the header is skipped.
An array reference can be used to simply pass through a list of headers unchanged.
It will default to the following headers:
The User-Agent is forwarded as X-Forwarded-User-Agent.
response
This is a hash reference (since v0.2.0) of request headers to return from the proxy. The keys are the response header fields, and the values are the headers that will be returned from the proxy.
Values of 1 will be a synonym for the same header, and false values will mean that the header is skipped.
An array reference can be used to simply pass through a list of headers unchanged.
It will default to the following headers:
wait
The number of seconds to wait for new content to be loaded.
LIMITATIONS
This does not support cache invalidation or screenshot rendering.
This only does the bare minimum necessary for proxying requests. You may need additional middleware for reverse proxies, logging, or security filtering.
SECURITY CONSIDERATIONS
By default, Chrome can access local files using the file: protocol.
By default, Chrome will run scripts.
This should only be used for trusted websites, e.g. adding a prerendering proxy for your own website.
SEE ALSO
Rendertron https://github.com/GoogleChrome/rendertron
SOURCE
The development version is on github at https://github.com/robrwo/perl-Plack-App-Prerender and may be cloned from https://github.com/robrwo/perl-Plack-App-Prerender.git
SUPPORT
Only the latest version of this module will be supported.
Future releases may only support Perl versions released in the last ten (10) years.
Please report any bugs or feature requests on the bugtracker website https://github.com/robrwo/perl-Plack-App-Prerender/issues
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.
Reporting Security Vulnerabilities
If the bug you are reporting has security implications which make it inappropriate to send to a public issue tracker, then see SECURITY.md for instructions how to report security vulnerabilities.
AUTHOR
Robert Rothenberg <perl@rhizomnic.com>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2020, 2026 by Robert Rothenberg.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)