Docker minperl

My attempt to get a super bare-bones container for running plack/starman Perl applications. It weighs in at about 67MB, so while lighter than a full OS image is still heavier than I would prefer. How it works:

Building

It uses a builder container based off perl:5.32.0-buster. This installs carton, copies over the cpanfile and builds a local lib for the application. It then uses a Perl script called finder.pl to discover the required shared .so files (XS) needed by the Perl interpreter and and base Perl modules. Finaly it bundles the minimal environment into a tarball and uses that in a second stage Dockerfile as a base image.

How to use it

• Customise cpanfile to suit dependency needs.
• Modify Dockerfile change CMD to what you need and copy any required files over.

• Run ./build.sh

  $ docker run -t minperl
  HTTP: Accepting connections at http://0:5000/

Why?

Because I wanted to know if it was possible. The builder container is needed because installing Perl modules requires a C compiler, and that essentially implies an OS image. However as long as the scratch image has the required shared object files that whole build environment is not really needed.