[cloud][inventory] Get tags for RDS instances. (#23989)

* Get tags for RDS instances.

Boto3 only at this time.

Relates to #11569, #14464.

* Add a check for boto3

* Fix HAS_BOTO3 error

contrib/inventory/ec2.py

@@ -623,6 +623,13 @@ class Ec2Inventory(object):
         ''' Makes an AWS API call to the list of RDS instances in a particular
         region '''
 
+        if not HAS_BOTO3:
+            self.fail_with_error("Working with RDS instances requires boto3 - please install boto3 and try again",
+                                 "getting RDS instances")
+
+        client = ec2_utils.boto3_inventory_conn('client', 'rds', region, **self.credentials)
+        db_instances = client.describe_db_instances()
+
         try:
             conn = self.connect_to_aws(rds, region)
             if conn:
@@ -630,7 +637,14 @@ class Ec2Inventory(object):
                 while True:
                     instances = conn.get_all_dbinstances(marker=marker)
                     marker = instances.marker
-                    for instance in instances:
+                    for index, instance in enumerate(instances):
+                        # Add tags to instances.
+                        instance.arn = db_instances['DBInstances'][index]['DBInstanceArn']
+                        tags = client.list_tags_for_resource(ResourceName=instance.arn)['TagList']
+                        instance.tags = {}
+                        for tag in tags:
+                            instance.tags[tag['Key']] = tag['Value']
+
                         self.add_rds_instance(instance, region)
                     if not marker:
                         break