Allows to override the aws profile for route53

In certain cases the aws stack belongs to a different sub account
than the route53 domains so certain operations could benefit by
crossing to a different sub account, using different credentials.

For now only the enter_maintenance and exit_maintenance tasks are
aware of this change.

bootstrap_cfn/fab_tasks.py

@@ -33,6 +33,7 @@
 env.setdefault('stack_passwords')
 env.setdefault('blocking', True)
 env.setdefault('aws_region', 'eu-west-1')
+env.setdefault('aws_r53', None)
 
 # GLOBAL VARIABLES
 TIMEOUT = 3600
@@ -66,6 +67,23 @@ def aws(profile_name):
     boto3.setup_default_session(profile_name=env.aws)
 
 
+@task
+def aws_r53(profile_name):
+    """
+    Set the AWS account to use for route53
+
+    Sets the environment variable 'aws_r53' to the name of the
+    account to use in the AWS config file (~/.aws/credentials.yaml)
+    and allows to override the 'aws' variable, for cases where the
+    Route53 zones exist under a different AWS account
+
+    Args:
+        profile_name(string): The string to set the environment
+        variable to
+    """
+    env.aws_r53 = str(profile_name).lower()
+
+
 @task
 def environment(environment_name):
     """
@@ -214,15 +232,28 @@ def apply_maintenance_criteria(elb):
     return elb['scheme'] == 'internet-facing'
 
 
+def override_route53_if_needed():
+    '''
+    Allows to override AWS account for Route53 Maintenance modes
+
+    Returns a dictionary with the route53 account specified in aws_r53 from
+    command line, eg "fab aws:account1 aws_r53:account2"
+    '''
+    if aws_r53:
+        return dict(aws=env.aws_r53)
+    else:
+        return {}
+
+
 @task
-def enter_maintenance(maintenance_ip):
+def enter_maintenance(maintenance_ip, dry_run=False):
     '''
     Puts stack into maintenance mode
 
     Sets all internet facing elb hostnames to resolve to given maintenance_ip
     '''
     cfn_config = get_config()
-    r53_conn = get_connection(R53)
+    r53_conn = get_connection(R53, **override_route53_if_needed())
 
     cached_zone_ids = {}
     for elb in cfn_config.data['elb']:
@@ -232,7 +263,7 @@ def enter_maintenance(maintenance_ip):
         record = "{name}.{hosted_zone}".format(**elb)
         zone_id = get_cached_zone_id(r53_conn, cached_zone_ids, elb['hosted_zone'])
         print green("Attempting to update: \"{0}\":\"{1}\"".format(record, maintenance_ip))
-        r53_conn.update_dns_record(zone_id, record, 'A', maintenance_ip)
+        r53_conn.update_dns_record(zone_id, record, 'A', maintenance_ip, dry_run=dry_run)
 
 
 @task
@@ -243,7 +274,7 @@ def exit_maintenance():
     Sets internet-facing elbs hostnames
     back to the ELB DNS alias
     """
-    r53_conn = get_connection(R53)
+    r53_conn = get_connection(R53, **override_route53_if_needed())
     elb_conn = get_connection(ELB)
 
     cfn_config = get_config()
@@ -453,9 +484,9 @@ def get_config():
     return cfn_config
 
 
-def get_connection(klass):
+def get_connection(klass, aws=env.aws, aws_region=env.aws_region):
     _validate_fabric_env()
-    return klass(env.aws, env.aws_region)
+    return klass(aws, aws_region)
 
 
 @task

bootstrap_cfn/r53.py

@@ -39,7 +39,7 @@ def get_hosted_zone_id(self, zone_name):
             zone = zone['GetHostedZoneResponse']['HostedZone']['Id']
             return zone.replace('/hostedzone/', '')
 
-    def update_dns_record(self, zone, record, record_type, record_value, is_alias=False):
+    def update_dns_record(self, zone, record, record_type, record_value, is_alias=False, dry_run=False):
         '''
         Updates a dns record in route53
 
@@ -62,7 +62,10 @@ def update_dns_record(self, zone, record, record_type, record_value, is_alias=Fa
             change.set_alias(*record_value)
         else:
             change.add_value(record_value)
-        changes.commit()
+        if dry_run:
+            print changes
+        else:
+            changes.commit()
         return True
 
     def get_record(self, zone, zone_id, record, record_type):