Jun 18, 2009

  • Category: Buildout, Plone, Python, Zope
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A Sane Buildout For repoze.zope2 + Plone

This is a follow-up to Martin Aspeli’s introduction to repoze and Plone from last year

A Tale of Two Buildouts

There are two stories going on here, both of which Martin Aspeli recently described in great detail and Chris McDonough tackled last year. For the purposes of this blog entry, I’ll refer to the issue as the “index vs. find-links” conundrum in buildout  (find-links in buildout are equivalent to distribution_links in setuptools).

For those that want strict repeatability, using the index parameter is the clear winner. It simply forces buildout to do the right thing now and forever, by limiting what packages it can select from. For those that want functionality and don’t mind the occasional egg-out-of-whack (i.e. unexpected upgrade), then using the find-links parameter can provide a “sexy” way to get decent results quickly (but may, and probably will, shoot you in the foot later).

Sexy, but Dangerous

Let’s start with the sexy, but with less repeat-ability method first. Using this method we are not specifying our own index. Therefore you are free to add any package from PyPI or plone.org as you see fit. This is essentially why people like this method (the counter argument is that it is simple to add any additional egg you may want to your index, but we’ll get to that later).

So a simple buildout using this method might look like this:

virtualenv plone; cd plone
bin/easy\_install zc.buildout
bin/buildout init
Edit buildout.cfg:
[buildout]
extends =
# Using Martin Aspeli's good-py, thanks!
    http://good-py.appspot.com/release/repoze.zope2/1.0
    http://dist.plone.org/release/3.3rc3/versions.cfg
versions = versions
find-links =
    http://dist.repoze.org/zope2/latest
    http://dist.repoze.org/zope2/dev/
    http://dist.plone.org/release/3.3rc3
parts = instance[instance]
recipe = zc.recipe.egg
dependent-scripts = true
eggs =
    repoze.zope2
    Plone
    PIL

4. bin/buildout

A few more steps are required, which we could certainly automate in buildout, but for now I’ll just list them here:

  1. bin/mkzopeinstance
  2. bin/addzope2user admin admin

Now, the moment we’ve all been waiting for… the fun part!

  1. bin/paster serve etc/zope2.ini

You should see something like:

[aclark@alex-clarks-macbook-pro]~/Developer/plone% bin/paster serve etc/zope2.ini
2009-06-18 22:52:24 INFO Marshall libxml2-python not available. Unable to register libxml2 based marshallers.
2009-06-18 22:52:27 WARNING ZODB.FileStorage Ignoring index for
/Users/aclark/Developer/p3-repoze-2/var/Data.fsDeprecationWarning: zope.app.annotation has moved to
zope.annotation. Import of zope.app.annotation will become
unsupported in Zope 3.5
/Users/aclark/Developer/plone/eggs/zopelib-2.10.7.0-py2.4-macosx-10.5-i386.egg/zope/configuration/xmlconfig.py:323:
  __import__(arguments[0])
------
2009-06-18T22:52:24 INFO Marshall libxml2-python not available. Unable to register libxml2 based marshallers.
------
2009-06-18T22:52:27 WARNING ZODB.FileStorage Ignoring index for /Users/aclark/Developer/plone/var/Data.fs
Starting server in PID 26900.
zserver on port 8080

At this point, you should be able to login to http://localhost:8080/manage and create a Plone site.

Of course, we did a sloppy job here, creating the Zope2 instance in the root of the buildout, etc. It is possible that plone.recipe.zope2install may help us in the future by supporting repoze.zope2 instances (or maybe it does already, I didn’t try).

Next up?

Boring, but Repeatable

I kid, but this is actually a very serious concern for many people, and rightfully so. The notion that your buildout will work the same today as it does in one year from now may be a strict requirement for your project. If it is, we can accommodate you (I hope) with the “index” buildout that follows. The downside is that *you* can’t control what I put in the index. However, you can certainly create your own index using this technique.

An arguably even simpler buildout using this technique might look like this:

  1. virtualenv plone; cd plone
  2. bin/easy_install zc.buildout
  3. bin/buildout init
  4. Edit buildout.cfg:
[buildout]
index = http://dist.plone.org/experimental/release/3.3rc3/simple/
parts = instance[instance]
recipe = zc.recipe.egg
dependent-scripts = true
eggs =
    repoze.zope2
    Plone
    PIL

4. bin/buildout

5. bin/mkzopeinstance

6. bin/addzope2user admin admin

7. bin/paster serve etc/zope2.ini

In Conclusion

Depending on what my needs are, I might choose either of these techniques. We can also hold out for multi-index support in setuptools. That would seemingly make everyone happy. In the meantime, I can tell you I’d definitely reach for a buildout sans custom index first, then ask questions later (i.e. wait for bleeding toes) but that is just me. If people find the “index” technique generally useful, I’d be willing to support package sheperding and index generating with basketweaver. Just let me know. If it really catches on, we could rename http://dist.plone.org/experimental/release/3.3rc3/ to http://dist.plone.org/repoze/release/3.3rc3/. Of course, if anyone objects to this or finds it confusing, I can just as easily remove it (from dist.plone.org).

Special thanks to Chris McDonough and Martin Aspeli for helping me scratch my itch!

Finally, please don’t rely on any of this “in production” yet unless you know what you are doing. I tested these techniques up to the point of starting Zope (via paste) and adding a Plone site, nothing more!

I, however, am getting a new server next week and will be hosting this site on repoze.zope2 very shortly ;-)

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