Eggs and Buildout Deployment in Python

Slides:

Four-Part In-Depth Presentation Sequence (not presented in class)

• An Introduction to the Virtualenv Sandbox (`.pdf`__, `.txt`__)
• Distutils: Packaging, Metadata and Pushups (`.pdf`__, `.txt`__)
• SetupTools: Python Eggs, Dependencies and Plugins (`.pdf`__, `.txt`__)
• Buildout: Precision Assembly, Repeatability, Islands (.pdf, .txt)

Condensed Slide Set Used in Actual Tutorial

• Eggs and Buildout Deployment in Python (`.pdf`__, `.txt`__)

• Additional Topics of Tutorial (`.pdf`__, `.txt`__)

Exercises from Tutorial:

1. Installing Tools for the Class

   $ cd /tmp

   $ wget http://peak.telecommunity.com/dist/ez_setup.py

   $ sudo python ez_setup.py

   $ sudo easy_install virtualenv

   $ sudo easy_install zc.buildout

2. Instantiating a Sandbox or Two

   $ virtualenv pycon -or-

   $ virtualenv --no-site-packages pycon

   $ cd pycon

   $ bin/python

   $ source bin/activate -or- activate.bat

   $ deactivate

   • explore:

     • directory tree
     • sys.path

   • for each kind of sandbox

3. Processing Distributions

   1. Grab a source distribution

      $ /sandbox/bin/easy_install --editable --build-directory . SQLObject==0.9.5

      $ /sandbox/bin/easy_install --editable --build-directory . SQLObject==dev

      Examine its directory structure and common files.

   2. Query the list of available distribution formats.

      $ cd sqlobject

      $ /sandbox/bin/python setup.py sdist --help-formats

      $ /sandbox/bin/python setup.py bdist --help-formats

   3. Build and package it as a binary distribution.

      $ /sandbox/bin/python setup.py build

      $ /sandbox/bin/python setup.py install

      $ /sandbox/bin/python setup.py bdist --formats=tar,egg,rpm

      Examine the run output and the table-of-contents of the distribution archive afterward. Note the way that metadata is stored.

   4. Repackage it as a source distribution

      $ /sandbox/bin/python setup.py sdist --formats=zip

      Examine the run output and the table-of-contents of the source archive. Note the different way that metadata is stored.

   5. Try to import it, then run the "develop" cmd and try again.

      $ cd /sandbox

      $ /sandbox/bin/python

      $ import sqlobject
      $ cd /sandbox/sqlobject

      $ /sandbox/bin/python setup.py develop

4. Generating Scripts that Invokes Entrypoints

   1. Create a sandbox in which to work.

      $ virtualenv --no-site-packages pycon

      $ cd pycon

   2. Create a distribution for a new egg that has two scripts.

      # File: pycon/setup.py

      from setuptools import setup

      
      

      setup(name="myscript",

      version="1.0.0",

      py_module = ['myscript'],

      entry_points={

      "console_scripts": [

      "alpha = myscript:alpha_cmd",

      "beta = myscript:beta_cmd"]

      },

      )
      # File: pycon/myscript.py

      def alpha_cmd():

      print "Hello from Alpha Centauri"

      
      

      class beta_cmd(object):

      def __init__(self):

      print "Hello from Beta Centauri"

   3. Mark it a develop-egg and then add the egg as a 'myscript' part.

      # File: pycon/buildout.cfg

      [buildout]

      develop = .

      parts = myscript

      
      

      [myscript]

      recipe = zc.recipe.egg

      eggs = myscript
   4. Run buildout and look in the bin/ directory for scripts.

5. Create a simple buildout around an egg and experiment with it.

   1. Create an empty buildout area.

      $ virtualenv --no-site-packages pycon

      $ cd pycon

      $ buildout init

   2. Put into it a simple egg by creating a "buildout.cfg" file:

      [buildout]

      parts = mypython

      prefer-final = true

      
      

      [mypython]

      recipe = zc.recipe.egg

      interpreter = dbpython

      eggs = SQLObject

   3. Invoke "bin/buildout" and examine the output messages, the directory structure and the dbpython script.

      Test for what version got installed and where it came from.

      $ bin/dbpython

      >>> import sqlobject

      >>> sqlobject.__file__

      '/var/tmp/buildout/eggs/SQLObject-0.10.0-py2.5.egg/sqlobject/__init__.py'

   4. Force it to use a specific version of SQLObject.

      eggs = SQLObject==0.9

      Test for what version got installed and where it came from.

      $ bin/dbpython

      >>> import sqlobject

      >>> sqlobject.__file__

      '/var/tmp/buildout/eggs/SQLObject-0.9.0-py2.5.egg/sqlobject/__init__.py'

   5. Remove that constraint and grab its source distribution.

      $ bin/easy_install --editable -b . SQLObject

      Alter "buildout.cfg" file to make it a development egg:

      develop = sqlobject

      Test for what version got installed and where it came from.

      $ bin/dbpython

      >>> import sqlobject

      >>> sqlobject.__file__

      '/tmp/kkk/sqlobject/sqlobject/__init__.py'