[chef] How would I prevent python_pip from installing packages that are already installed?

[Fabien Delpierre < >]

Hello folks,

I have the following bit of code:

reqs.each do |req|
  python_pip req do
    virtualenv /foo
    action :upgrade
    not_if "ls -1 /foo/lib/python33/site-packages | grep #{req}"
  end
end

Now, reqs is a pretty large list of pip packages (probably about 30) compiled from a requirements file. Additionally, each package has a specific version requirement.

So whenever Chef runs, it painstakingly attempts to upgrade every package listed in reqs despite my apparently feeble and incompetent not_if. It causes my Chef run to take 5-7 minutes instead of 2-3. This is fine for the first run, but this is a development VM for a team that iterates pretty fast, so 5-7 minute "compile times" are going to be a drag.

One strange thing that might be relevant is that the Chef log reads something like the below line for each pip package:

==> default: [2015-03-06T13:02:05-05:00] INFO: Upgrading python_pip[alembic==0.6.4] version from uninstalled to latest

Note that it says "uninstalled" even though the package is definitely installed.

$ pip list
pip (6.0.8)
setuptools (12.4)
virtualenv (12.0.7)

$ source /foo/bin/activate
(foo)$ pip list
alembic (0.6.4)
...
pip (6.0.8)
...
setuptools (13.0.2)
...

(foo)$

Interestingly though, there is one package in reqs without a version requirement, it's gunicorn. When Chef tries to install it, it says this instead:

==> default: [2015-03-06T13:01:57-05:00] INFO: Upgrading python_pip[gunicorn] version from 19.3.0 to latest

Frankly it shouldn't even be trying to install gunicorn anyway, but it's interesting/weird to me that for this one package, it accurately detects that it's installed and returns the installed version, whereas all the other ones report that they're uninstalled even though that's wrong.

The ls command in my not_if returns the correct code whether the virtual environment is active or not.

$ ls -1 /foo/lib/python3.3/site-packages | grep alem; echo $?
alembic
alembic-0.6.4-py3.3.egg-info
0
$ ls -1 /foo/lib/python3.3/site-packages | grep foo; echo $?
1

So unless I'm off the mark with my logic, the python_pip resource should execute only if grep returns 1... but that's not the case and I'm confused and help please pretty please with powdered sugar and a cherry on top.

Thanks in advance!

Fabien