Bundling up a perl script with its dependencies?

Question

I have a perl script that I've put together to do some monitoring and graphing.

It works nicely on my dev system, where I have carte-blanch to install my own modules from CPAN.

What I'm looking at doing is bundling it up to deploy onto another system. But here's the catch - this other system is 'standalone' and has no network connection. (And I have change control paperwork to fill in, indicating what I'm installing).

As a result, I'd really like a nice easy way to figure out: - What modules my scripts are making use of. (Including dependencies) - how to easily grab them (cpan get probably) - Is there an easy way to tell what external binaries I'm using? (I'm using for sure ssh and rrdtool - the former is definitely installed, the latter probably not).

I have a few thoughts on how to do this, but it strikes me as something that should be smoother.

I may also need to deploy a new perl, so I'm pondering whether I'm better off 'installing' the modules with system perl (probably 5.8.8 on RHEL5), or just 'packaging' the whole thing in a directory of it's own with a standalone perl instance.

Answer 1

Revisiting this, as the need hasn't really gone away. I have moved towards using docker - this is an 'image' and 'container' system for app deployment, which amongst other things, allows you to 'package' an application.

You create a Dockerfile - which is analagous to a Makefile - that runs through the steps to install perl + dependencies (either via a package manager, or from CPAN).

Once it has, you have a self contained, runnable 'image' that you can clone and create an instance of (a "container" in docker parlance).

It's also quite useful - even if you don't then deploy via container - to figure out what the dependencies of this application/packages were. The version in the container has everything locally installed that it needed, because it was a clean build.

Answer 2

When you have a system where you can't control the Perl installation (and the install is a really, really old version of Perl like 5.8.8 which is missing many nice improvements like state variables, autodie, say, and switch), you should look into Perlbrew.

Perlbrew allows you to install a user version of Perl. (In fact, it allows you to install multiple versions of Perl), and allows you to switch between the Perlbrew install and the officially installed version. It makes doing everything in Perl much, much easier.

You will have freer access to install new Perl modules, and you can do that task yourself rather than wait for your IT department to do it for you.

I ended up using it on one of our systems where the primitive version of Perl just wasn't doing what my version of Perl did. I originally asked our IT to upgrade, but they really messed up the upgrade. After going back and forth, I simply asked if I could install Perlbrew.

Which is an important point. Always ask permission. A lot of time, the IT department is more than happy to oblige. They're not Perl people, and CPAN is a world they don't want to deal with. Being able to get out of having to answer your beck and call about installing this or that Perl module is a great relief.

Answer 3

Use pp to package your script and all dependant modules and libraries into a stand alone executable.

pp -x yourscript.pl -o outputfilename

See the documentation for examples of how to link to external shared objects (etc) if required. With pp you don't need perl on the target system where outputfilename will run.