Auto installation of a C library during/before a CPAN install

cmac has asked for the wisdom of the Perl Monks concerning the following question:

I'm working on a module that has an accompanying script that can be scheduled (cron'ed on Unix/Linux) to update its database from the internet. The biggest problem with this, that is not covered by LWP, is that of proxies.

I know how to access environment variables plus the CPAN config to automatically take care of many systems that include a proxy. Nevertheless if none of these contain anything, I feel that I have to include a query during Build.PL execution, to ask if there's a proxy. (Of course there will be a default "n" to take care of smoke-testing.)

If the query (which is only asked if the environment/CPAN variables don't identify a proxy) comes back "y", I know how to run a WPAD protocol, and if that doesn't yield anything, how to search on Windows for *.pac.

Q1: where should one search for *.pac on non-Windows systems?

But my main problem is when a wpad or pac search succeeds. Now I have a Javascript file that can tell my script what proxy should be used for a URL that it wants to access. The only viable module that I've been able to find on CPAN to help with this is called HTTP::ProxyPAC.

HTTP::ProxyPAC has JavaScript as a prerequisite. The JavaScript bindings expect that the user must have 'libjs' from Mozilla installed (by hand) before it will install. And if jslib is present, the JavaScript installer asks 3 scary questions about how it was installed, to which only a true wizard would know the answers.

I would like to use ProxyPAC and JavaScript but don't want to subject my installers to such pain. I can put the .tar.gz of libjs from Mozilla inside my module, and drive the installation from Build.PL if it is needed. (Running a proxy.pac or wpad.dat file hardly needs the latest version!)

Q2: can libjs can be installed by Build.PL before the CPAN code prepends HTTP::ProxyPAC and then JavaScript and tries to install them (based on META.yml) before it ever runs my Build.PL?

Answers to these Qs, and any other comments or advice on the best way to handle this matter, will be much appreciated.

Comment on Auto installation of a C library during/before a CPAN install

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Re: Auto installation of a C library during/before a CPAN install by Corion (Patriarch) on Mar 02, 2010 at 08:05 UTC
In my experience, LWP handles proxies well if `$ENV{HTTP_PROXY}` is set. I would think that it's easier to put the burden of configuration on the users who are behind a proxy and want to run your script from there, instead of burdening all your module users with installing JavaScript, just so they can run that optional auto-update script. If you're looking at how to install a C libraryfor your modules, look at how Alien::Wx does it, or package the C library directly.	[reply] [d/l]

Replies are listed 'Best First'.

Re: Auto installation of a C library during/before a CPAN install
by Corion (Patriarch) on Mar 02, 2010 at 08:05 UTC

In my experience, LWP handles proxies well if $ENV{HTTP_PROXY} is set. I would think that it's easier to put the burden of configuration on the users who are behind a proxy and want to run your script from there, instead of burdening all your module users with installing JavaScript, just so they can run that optional auto-update script.

If you're looking at how to install a C libraryfor your modules, look at how Alien::Wx does it, or package the C library directly.

[reply]
[d/l]