NAME

Plack::App::Prerender - a simple prerendering proxy for Plack

VERSION

version v0.2.0

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 Chrone.

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 chould 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, [], [] ];
    }

    ...
  }

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 fieldss, 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:

X-Forwarded-For
X-Forwarded-Host
X-Forwarded-Port
X-Forwarded-Proto

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:

Content-Type
Expires
Last-Modified

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.

SEE ALSO

Plack

WWW::Mechanize::Chrome

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 git://github.com/robrwo/perl-Plack-App-Prerender.git

BUGS

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.

AUTHOR

Robert Rothenberg <rrwo@cpan.org>

COPYRIGHT AND LICENSE

This software is Copyright (c) 2020 by Robert Rothenberg.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)