Allow filtering EIPs by AWS tag (New --tag parameter)

README.md

@@ -32,9 +32,11 @@ credential config options](http://boto.readthedocs.org/en/latest/boto_config_tut
 and AWS instance profiles.
 
     usage: aws-ec2-assign-elastic-ip [-h] [--version] [--region REGION]
-                                     [--access-key ACCESS_KEY]
-                                     [--secret-key SECRET_KEY] [--dry-run]
-                                     [--valid-ips VALID_IPS]
+                                 [--access-key ACCESS_KEY]
+                                 [--secret-key SECRET_KEY] [--dry-run]
+                                 [--valid-ips VALID_IPS]
+                                 [--invalid-ips INVALID_IPS]
+                                 [--tag [KEY=VALUE]]
 
     Assign EC2 Elastic IP to the current instance
 
@@ -63,7 +65,10 @@ and AWS instance profiles.
                             - 58.0.0.0/8
                             - 123.213.0.0/16,58.0.0.0/8,195.234.023.0
                             - 195.234.234.23,195.234.234.24
-
+      --tag [KEY=VALUE]     A case-sensitive tag (key=value pair) that valid Elastic IPs should have
+                            Valid examples:
+                            - Name=my-eip
+                            - Group=prod
 
 The `--valid-ips` and `--invalid-ips` options require the public IPs in a comma separated sequence.
 E.g. `56.123.56.123,56.123.56.124,56.123.56.125`.

aws_ec2_assign_elastic_ip/__init__.py

@@ -132,6 +132,14 @@ def _get_unassociated_address():
                 address['PublicIp'], address['NetworkInterfaceId']))
             continue
 
+        # Check if the address has the correct tag
+        if not _has_correct_tag(address):
+            logger.debug(
+                '{0} is unassociated, but does not have correct tag'.format(
+                    address['PublicIp']))
+            continue
+
+
         # Check if the address is in the valid IP's list
         if _is_valid(address['PublicIp']):
             logger.debug('{0} is unassociated and OK for us to take'.format(
@@ -161,6 +169,29 @@ def _has_associated_address(instance_id):
         return True
     return False
 
+
+def _has_correct_tag(address):
+    """ Check if the EIP has given tag
+
+    :type address: str
+    :param address: IP address to check
+    :returns: bool -- True if IP address has tag
+    """
+    if not args.tag:
+        return True
+
+    (tag_key, tag_value) = args.tag.split('=')
+
+    try:
+        for address_tag in address['Tags']:
+            if address_tag['Key'] == tag_key and address_tag['Value'] == tag_value:
+                return True
+    except KeyError as error:
+        logger.debug('IP: {0} has no tags assigned'.format(address['PublicIp']))
+        return False
+
+    return False
+
 def _is_ip_in_range(address, ips):
     """ Check if the IP is in a given range.
 

aws_ec2_assign_elastic_ip/command_line_options.py

@@ -56,6 +56,15 @@
         '- 58.0.0.0/8\n'
         '- 123.213.0.0/16,58.0.0.0/8,195.234.023.0\n'
         '- 195.234.234.23,195.234.234.24\n'))
+PARSER.add_argument(
+    '--tag',
+    metavar="KEY=VALUE",
+    nargs='?',
+    help=(
+        'A case-sensitive tag (key=value pair) that valid Elastic IPs should have\n'
+        'Valid examples:\n'
+        '- Name=my-eip\n'
+        '- Group=prod\n'))
 ARGS = PARSER.parse_args()
 
 if ARGS.version: