adding include_pattern and exclude_pattern options to ec2.py

plugins/inventory/ec2.ini

@@ -67,3 +67,9 @@ cache_max_age = 300
 
 # Organize groups into a nested/hierarchy instead of a flat namespace.
 nested_groups = False
+
+# If you only want to include hosts that match a certain regular expression
+# pattern_include = stage-*
+
+# If you want to exclude any hosts that match a certain regular expression
+# pattern_exclude = stage-*

plugins/inventory/ec2.py

@@ -252,6 +252,22 @@ class Ec2Inventory(object):
         else:
             self.nested_groups = False
 
+        # Do we need to just include hosts that match a pattern?
+        try:
+            pattern_include = config.get('ec2', 'pattern_include')
+            if pattern_include and len(pattern_include) > 0:
+                self.pattern_include = re.compile(pattern_include)
+        except ConfigParser.NoOptionError, e:
+            self.pattern_include = None
+
+        # Do we need to exclude hosts that match a pattern?
+        try:
+            pattern_exclude = config.get('ec2', 'pattern_exclude');
+            if pattern_exclude and len(pattern_exclude) > 0:
+                self.pattern_exclude = re.compile(pattern_exclude)
+        except ConfigParser.NoOptionError, e:
+            self.pattern_exclude = ''
+
     def parse_cli_args(self):
         ''' Command line argument processing '''
 
@@ -359,6 +375,14 @@ class Ec2Inventory(object):
             # Skip instances we cannot address (e.g. private VPC subnet)
             return
 
+        # if we only want to include hosts that match a pattern, skip those that don't
+        if self.pattern_include and not self.pattern_include.match(dest):
+            return
+
+        # if we need to exclude hosts that match a pattern, skip those
+        if self.pattern_exclude and self.pattern_exclude.match(dest):
+            return
+
         # Add to index
         self.index[dest] = [region, instance.id]