Local CPAN modules

[Jeppe]

Esteemed monks,

I'm writing a build/test/installation script for the application we develop and maintain. As a part of this script, I would like to install a considerable number of CPAN modules, and I cannot count on an internet connection. In fact, we would like to not download automatically from the internet. Working on a static list of modules and a static list of versions of the modules means less time hunting down unexpected interactions..

However, there is an interesting challenge involved:

Let's say I've got all my modules in a directory, in tarball distributions. How do I then figure out which one require which one? I plan on creating a Makefile that represents the requirements and run that. But how do I figure out what module depends on what module?

[Corion]

My approach is to create a local CPAN mirror by using CPAN::Mini. This will be a fully functional CPAN mirror that will maybe even still fit on a CD.

If you don't want to go the route of shipping the full CPAN with your product, you can look at DrHyde's work for cpandeps ("temporary offline" unfortunately), but I guess he's got the code for tracking the dependencies online somewhere as well.

[Tanktalus]

Been there, done that. :-)

What I do is simply do this:

1. Untar everything (check if it's untarred already)
2. Loop:
   1. If Build.PL exists:
      • Run $^X -I$install_base/lib Build.PL --install_base $install_base, and catch the output.
      • Check for /ERROR: Prerequisite (\S+) isn't installed/. If found, go to next item in loop.
      • Run $^X Build install (if failed, go to next item)
      • Delete current build from to-do hash.
      else if Makefile.PL exists:
      • Run $^X -I$install_base/lib Makefile.PL LIB=$install_base/lib PREFIX=$install_base, and catch the output.
      • Check for /prerequisite\s*(\S+)\s.*not found/. If found, go to next item in loop.
      • Run make install (if failed, go to next item)
      • Delete current build from to-do hash.
3. After each iteration of the loop, if the size of the to-do hash is non-zero and hasn't changed (meaning some prereqs may not be satisfied, or some installs failed), bail. (This is important :->)
Obviously, I do this in perl. I don't even want to know how to do it in make - at least, automatically, that is. If it were in make, I'd just set up a bunch of targets where "DBD-mySQL: DBI" or something ... but that sounds painful, too :-)

[Jeppe]

Thanks! I had that algorithm in the back of my head, but I had hoped to do something .. more elegant. Oh well. No tux and lotsa elbow grease will get the job done!

[perrin]

What problem are you trying to solve? Modules that require others to be installed before they will install? There are very few of these and most are obvious (e.g. DBD::mysql requires DBI).

If you just want to know if you got all the dependencies, there are multiple tools on CPAN for determining module dependencies, like Module-ScanDeps.