Ohai: Add support for pre-2.6 versions of python

The Ohai plugin now works with servers using python 2.4-2.5 alongside
the python-simplejson python module.

Signed-off-by: Sol Jerome <solj@ices.utexas.edu>

git-svn-id: https://svn.mcs.anl.gov/repos/bcfg/trunk/bcfg2@5748 ce84e21b-d406-0410-9b95-82705330c041

2 files changed, 53 insertions, 2 deletions

diff --git a/doc/server/plugins/probes/index.txt b/doc/server/plugins/probes/index.txt
index f723ad528..3c5387180 100644
--- a/doc/server/plugins/probes/index.txt
+++ b/doc/server/plugins/probes/index.txt
@@ -126,3 +126,37 @@ Other examples
    manufacturer
    producttype
    serial-console-speed
+
+===========
+Ohai probes
+===========
+
+.. _Ohai: http://wiki.opscode.com/display/ohai/Home
+.. _Ohai-Install: http://wiki.opscode.com/display/ohai/Installation
+
+The `Ohai`_ plugin is used to detect information about the client
+operating system. The data is reported back to the server using JSON.
+
+Client prerequisites
+====================
+
+On the client, you need to install `Ohai`_. See `Ohai-Install`_ for more
+information.
+
+Server prerequisites
+====================
+
+If you have python 2.6 or later installed, you can continue on to
+:ref:`ohai-setup`. Otherwise, you will need to install the
+python-simplejson module found packaged in most distributions.
+
+.. _ohai-setup:
+
+Setup
+=====
+
+To enable the Ohai plugin, you need to first create an ``Ohai`` directory
+in your Bcfg2 repository (e.g. ``/var/lib/bcfg2/Ohai``). You then need
+to add **Ohai** to the plugins line in ``bcfg2.conf``. Once this is done,
+restart the server and start a client run. You will have the JSON output
+from the client in the ``Ohai`` directory you created previously.
diff --git a/src/lib/Server/Plugins/Ohai.py b/src/lib/Server/Plugins/Ohai.py
index 02d6ef58b..c18bcbbce 100644
--- a/src/lib/Server/Plugins/Ohai.py
+++ b/src/lib/Server/Plugins/Ohai.py
@@ -1,10 +1,26 @@
-
-import json
 import lxml.etree
 import os
+
+import logging
+logger = logging.getLogger('Bcfg2.Plugins.Ohai')
+
 import Bcfg2.Server.Plugin
 
+try:
+    import json
+except:
+    # FIXME: can be removed when server prereq is >= python 2.6
+    # necessary for clients without the in-tree json module
+    try:
+        import simplejson as json
+    except:
+        logger.error("Unable to load any json modules. Make sure "
+                     "python-simplejson is installed.")
+        raise ImportError
+
+
 class OhaiCache(object):
+
     def __init__(self, dirname):
         self.dirname = dirname
         self.cache = dict()
@@ -27,6 +43,7 @@ class OhaiCache(object):
         data.extend([x[:-5] for x in os.listdir(self.dirname)])
         return data.__iter__()
 
+
 class Ohai(Bcfg2.Server.Plugin.Plugin,
            Bcfg2.Server.Plugin.Probing,
            Bcfg2.Server.Plugin.Connector):