Re: gitweb, FastCGI and PSGI/Plack

On Sun, 9 May 2010, Tatsuhiko Miyagawa wrote:

You don't need to be subscribed to post to git mailing list. I personally read it with a news reader using GMane NNTP interface

  nntp://news.gmane.org/gmane.comp.version-control.git

but sending messages via email, to git@ver.kernel.org. Usually people reply both to original poster and to git mailing list, but just in case you can mention that you are not subscribed, and to not forget to send you a CC copy.

All CC re-added.

Ah, so that is why CGI distribution has FCGI as requirement!

  http://deps.cpantesters.org/?module=CGI;perl=latest

Yes, it doesn't.

Nevertheless gitweb would try to require CGI::Fast only when it is run
with '--fastcgi' / '--fcgi' / '-f' option.  It should probably check if
it can be require'd without errors, like it is done for FCGI::ProcManager
in
  [RFC/PATCHv2 2/2] gitweb: Add support for FastCGI, using CGI::Fast
  Message-Id: <201005080959.01800.jnareb@gmail.com>
  http://article.gmane.org/gmane.comp.version-control.git/146647

I didn't implement support for PSGI/Plack, at least not in patch send in "[PATCH 0/2] gitweb: Add support for running gitweb as FastCGI script" series.

Adding support for FastCGI to CGI application is as simple as using CGI::Fast object in place of CGI, and wrapping running main subroutine in a loop that processes requests, like described in CGI::Fast manpage. Well, for gitweb it required a few more small changes, anyway...

Moving to PSGI, or adding possibility to run gitweb as PSGI script (like the series adds *ability* to run gitweb as FastCGI script) by modifying gitweb would not be that easy, even with help of CGI::PSGI.

CGI::Compile was referring to an alternate approach, where instead of modifying gitweb to be able to run it as FastCGI script (you can run it as CGI script and as ModPerl::Registry script from mod_perl) there was added gitweb.fcgi wrapper:

JN> The alternate solution would be to add gitweb.fcgi wrapper, like e.g.: JN> in the following patch by Eric Wong JN> JN> "[PATCH 1/2] gitweb: add a simple wrapper for FCGI support" JN> http://thread.gmane.org/gmane.comp.version-control.git/35920/focus=35921 JN> JN> which was part of the "[0/2 PATCH] FastCGI and nginx support for gitweb" JN> series. (Note that the patch does 'do $gitweb_cgi;' without checking for JN> errors, see the bottom of `perldoc -f do` documentation on how it should JN> be done).

One can of course use this approach wrapping gitweb to be run on PSGI, using CGI::Emulate::PSGI (via Plack::App::WrapCGI), which in turn uses CGI::Compile. The gitweb.fcgi wrapper could use CGI::Emulate::FCGI... if it existed.

NB I use the following gitweb.psgi wrapper to run gitweb from "plackup" for tests (after running "make gitweb", of course, and with appropriate gitweb_config.perl, unversioned, in gitweb/ alongside gitweb.perl, the gitweb.psgi wrapper, and generated gitweb.cgi):

-- 8< -- #!/usr/bin/env plackup

# gitweb - simple web interface to track changes in git repositories # PSGI wrapper (see http://plackperl.org)

use strict; use warnings;

use Plack::Builder; use Plack::App::WrapCGI; use CGI::Emulate::PSGI 0.07; # minimum version required to work

use File::Spec;
# __DIR__ is taken from Dir::Self __DIR__ fragment
sub __DIR__ () {
	File::Spec->rel2abs(join '', (File::Spec->splitpath(__FILE__))[0, 1]);
}

builder {
	enable 'Static',
		path => sub { m!\.(js|css|png)$! && s!^/gitweb/!! }, root => __DIR__."/";
	Plack::App::WrapCGI->new(script => __DIR__."/gitweb.cgi")->to_app;
}

__END__ -- >8 --

It is a pity that Plack::App::WrapFCGI / FCGI::Emulate::PSGI does not exist, so that gitweb.psgi wrapper would not require indirectly CGI::Compile.

Email not good?