Add support for filtering EC2 instances in dynamic inventory

This allows filtering out EC2 instances based on various different
filters including tags. As requested in 7480 it supports logical "OR"
instead of "AND" on the provided list of filters.

plugins/inventory/ec2.py

@@ -123,6 +123,7 @@ from boto import ec2
 from boto import rds
 from boto import route53
 import ConfigParser
+from collections import defaultdict
 
 try:
     import json
@@ -272,6 +273,13 @@ class Ec2Inventory(object):
         except ConfigParser.NoOptionError, e:
             self.pattern_exclude = None
 
+        # Instance filters (see boto and EC2 API docs)
+        self.ec2_instance_filters = defaultdict(list)
+        if config.has_option('ec2', 'instance_filters'):
+            for x in config.get('ec2', 'instance_filters', '').split(','):
+                filter_key, filter_value = x.split('=')
+                self.ec2_instance_filters[filter_key].append(filter_value)
+
     def parse_cli_args(self):
         ''' Command line argument processing '''
 
@@ -316,7 +324,13 @@ class Ec2Inventory(object):
                 print("region name: %s likely not supported, or AWS is down.  connection to region failed." % region)
                 sys.exit(1)
 
-            reservations = conn.get_all_instances()
+            reservations = []
+            if self.ec2_instance_filters:
+                for filter_key, filter_values in self.ec2_instance_filters.iteritems():
+                    reservations.extend(conn.get_all_instances(filters = { filter_key : filter_values }))
+            else:
+                reservations = conn.get_all_instances()
+
             for reservation in reservations:
                 for instance in reservation.instances:
                     self.add_instance(instance, region)