What is difference in buildout between eggs and parts?

Question

There is 2 directories when you work with buildout: eggs and parts. Also there are declarations of eggs and parts in buildout.cfg. What is purpose of those elements of buildout system?

Answer 1

Very simple:

• Parts are the building blocks of your buildout. Different parts run different tasks, based on the recipe that is declared for them and the settings configured in that part.

  The parts subdirectory hold the bookkeeping information for each part. It depends on the recipe what is stored here. A CMMI recipe might install the result of the config/make/make install cycle here, for example.

• Eggs are python package distributions. Buildout uses code from eggs to provide recipe implementations, and most buildouts specify eggs for parts to use in the applications and scripts being built.

  It is perfectly legal to have a buildout that doesn't build anything that uses eggs itself. But for buildout to run the parts, eggs are going to be involved, under the hood.

  The eggs subdirectory usually holds the eggs used for both recipes and anything that requires eggs to run.