Idea for implementing reproducible builds

[Claudius Heine <claudius.heine.ext@siemens.com>]

Hi,

I am still working on reproducible builds and here is my current idea to 
solve this.

Simple put: Mount the /var/cache/apt/archives of the images and 
buildchroot to the isar-bootstrap root file system and then create a 
tarball of it. This way we have a tarball of the build just after 
debootstrap + upgrade with the one 'apt update' step done, but without 
any other changes to it and all used packages already in the apt package 
cache.

When restoring just skip most of the isar-bootstrap steps and extract 
the tarball instead, since the packages are available in the package 
cache and the package index is not updated it will use the packages from 
the cache.

This way we would side step the obstacle to make debootstrap 
reproducible by just using its product while the reset of the process 
can be redone by isar.

Is this solution enough? Or are you seeing any problem with this approach?

Claudius

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