Add playbook example for first_available_file

examples/playbooks/selective_file_sources.yml

+---
+# this is an example of how to template a file over using some variables derived
+# from the system.  For instance, if you wanted to have different configuration
+# templates by OS version, this is a neat way to do it.  Any Ansible facts, facter facts,
+# or ohai facts could be used to do this.  
+
+- hosts: all
+
+  tasks:
+
+  - name: template a config file
+    action: template dest=/etc/imaginary_file.conf
+    first_available_file:
+
+       # first see if we have a file for this specific host
+       - /srv/whatever/{{ ansible_hostname }}.conf
+
+       # next try to load something like CentOS6.2.conf
+       - /srv/whatever/{{ ansible_distribution }}{{ ansible_distribution_version }}.conf
+
+       # next see if there's a CentOS.conf
+       - /srv/whatever/{{ ansible_distribution }}.conf
+
+       # finally give up and just use something generic
+       - /srv/whatever/default
+
+
+

lib/ansible/runner.py

@@ -391,6 +391,7 @@ class Runner(object):
         # apply templating to source argument
         inject = self.setup_cache.get(conn.host,{})
         
+        # FIXME: break duplicate code up into subfunction
         # if we have first_available_file in our vars
         # look up the files and use the first one we find as src
         if 'first_available_file' in self.module_vars: