3. The problem
Multiple environments (dev, qa, staging, production) requiring
different buildout configurations.
$ bin/buildout -c dev.cfg
$ bin/buildout -c qa1.cfg
$ bin/buildout -c qa2.cfg
ad nauseum ...
The non-dev builds are performed by release engineers who
have better things to do than to read complicated release
notes to figure out the right buildout incantation for the
current environment.
Wednesday, November 9, 2011
4. The solution
Add environment variables into each non-dev environment
and have buildout figure out which config is the right one.
Wednesday, November 9, 2011
5. First try...
Used a buildout extension to munge the buildout config
dynamically. Similar to the way collective.recipe.python works.
Two issues:
1) The variant configs are hard to read.
2) Doesn't play well with mr.developer since "bin/develop"
turns off extensions when reading the config.
This was painful so I redid this w/o the buildout extensions...
Wednesday, November 9, 2011
6. Nothing fancy...
$ bin/buildout
-c config/variant-staging.cfg
buildout:directory=<<PATH TO BUILDOUT ROOT>>
The "buildout:directory" value fixes the problem where
buildout assumes the build context is the directory where the
main config resides.
Now, I just need a script to generate this call to buildout...
$ bin/environ
Let's make this script...
Wednesday, November 9, 2011
7. import os
import sys
import logging
import subprocess
logger = logging.getLogger('buildout.variants')
logger.setLevel(logging.INFO)
handler = logging.StreamHandler()
handler.setFormatter(logging.Formatter('%(message)s'))
logger.propagate = False
logger.addHandler(handler)
log = logger.info
# Is config file specified on command line?
config_file = False
args_in = sys.argv[1:]
while args_in:
op = args_in.pop(0)
if op[:2] == '-c':
config_file = True
log("buildout.variants: Disabled.")
# If config file not specified, check for one matching the environment
args = ['bin/buildout']
if not config_file:
environ = os.environ.get('BUILDOUT_ENVIRON')
if environ:
log("buildout.variants: Detected environment '%s'" %environ)
config_file = 'config/variant-%s.cfg' %environ
if not os.path.exists(config_file):
log("buildout.variants: Not found '%s'" %config_file)
config_file = False
if config_file:
args.append('-c%s' %config_file)
args.append('buildout:directory=%s' %os.getcwd())
log("buildout.variants: Applying variant '%s'" %config_file)
else:
log("buildout.variants: No variants found.")
# Run buildout
args = args + sys.argv[1:]
subprocess.call(args)
Wednesday, November 9, 2011
8. # Is config file specified on command line?
config_file = False
args_in = sys.argv[1:]
while args_in:
op = args_in.pop(0)
if op[:2] == '-c':
config_file = True
log("buildout.variants: Disabled.")
Wednesday, November 9, 2011
9. # Check the environment
args = ['bin/buildout']
if not config_file:
environ = os.environ.get('BUILDOUT_ENVIRON')
if environ:
log("buildout.variants: Detected '%s'" %environ)
config_file = 'config/variant-%s.cfg' %environ
if not os.path.exists(config_file):
log("buildout.variants: Not found '%s'" %config_file)
config_file = False
if config_file:
args.append('-c%s' %config_file)
args.append('buildout:directory=%s' %os.getcwd())
log("buildout.variants: Applying variant '%s'" %config_file)
else:
log("buildout.variants: No variants found.")
Wednesday, November 9, 2011
10. # Run buildout script
args = args + sys.argv[1:]
subprocess.call(args)
Wednesday, November 9, 2011
11. release engineers = :-)
Only need to know one command to update a buildout
$ bin/environ
Environment buildouts can always be overridden.
$ bin/environ -c local.cfg
or
$ BUILDOUT_ENVIRON=staging bin/environ
Wednesday, November 9, 2011
12. Extra credit
All the documentation says to run buildout with...
$ bin/buildout
Let's not confuse the release engineers with yet another way
to run a buildout so I just created a custom buildout script
(generated by the bootstrap.py) that folds this environment
hook into bin/buildout itself.
[customizing buildout script left as an exercise for the reader]
So no more 'bin/environ'. Just 'bin/buildout' again.
Release engineers even happier :-)
Wednesday, November 9, 2011
13. An alternative
Another way to get environment-aware buildout configurations
is with mr.scripty,
http://pypi.python.org/pypi/mr.scripty
Allows defining values in a buildout part with regular python
expressions. This is possibly a more general solution although
the configs may be a little harder to read. You also can't adjust
a buildout config "extends" value with this method.
Wednesday, November 9, 2011
14. Another problem
Staging environment sucks.
Occasionally, stuff in python site packages in staging borks the
buildout. I could work on fixing the staging environment but
I've got better things to do.
So let's isolate the buildout from site packages.
Some possible solutions...
1) virtualenv
2) zc.buildout, version 1.5.x
Let's show the virtualenv method...
Wednesday, November 9, 2011
15. Release notes 2.0
Using virtualenv...
$ hg clone <path-to-repo> MyBuildout
$ virtualenv --no-site-packages MyBuildout
$ cd MyBuildout
$ bin/python bootstrap.py
$ bin/buildout
Wednesday, November 9, 2011
16. A virtualenv bootstrap
Virtualenv must be installed, or we need to create a bootstrap.
$ virtualenv.create_bootstrap_script(extra_text)
The extra_text is just some python script to hook in extra
behavior during a bootstrap.
extend_parser(optparse_parser):
Add or remove options from the parser here.
adjust_options(options, args):
Change options or args here.
after_install(options, home_dir):
After everything is installed, this function is called.
See the virtualenv docs for details.
Wednesday, November 9, 2011
17. (cont.)
>>> extra_text = """
>>> def adjust_options(options, args):
>>>
>>> # Create virtualenv in current dir
>>> args = ['.']
>>>
>>> # Isolate from system python site-packages
>>> options.no_site_packages = True
>>>
>>> # Use distribute instead of setuptools
>>> options.use_distribute = True
>>> """
>>>
>>> import virtualenv
>>> out = virtualenv.create_bootstrap_script(extra_text)
>>> open('virtualenv.py', 'w').write(out)
Wednesday, November 9, 2011
18. Release notes 3.0
Virtualenv not installed in system python...
$ hg clone <path-to-repo> MyBuildout
$ cd MyBuildout
$ python2.6 virtualenv.py
$ bin/python bootstrap.py
$ bin/buildout
Wednesday, November 9, 2011
19. But wait, there's more
Add the following to the virtualenv bootstrap script,
def after_install(options, home_dir):
if os.path.exists('bootstrap.py'):
logger.notify('Running bootstrap.py')
subprocess.call([os.path.join(home_dir, 'bin', 'python'),
'bootstrap.py'])
Now bootstrapping virtualenv also bootstraps buildout.
Wednesday, November 9, 2011
21. Conclusion
* Much simpler release process... happy release engineers.
* Much simpler release notes... happy developers
* Joy all around.
Wednesday, November 9, 2011
![First, a basic buildout
[buildout]
parts =
pyramid
myapp
[pyramid]
recipe = zc.recipe.egg
dependent-scripts = true
eggs = pyramid
interpreter = py
[myapp]
recipe = collective.recipe.template
input = templates/myapp.ini.in
output = ${buildout:directory}/etc/myapp.ini
key_a = value_a
key_b = value_b
Wednesday, November 9, 2011](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)