route53-migrate-zone now handles existing records gracefully.

route53-migrate-zone/route53-migrate-zone.py

@@ -20,13 +20,23 @@ def commit_record_changeset(to_zone_record_changeset):
         sys.stdout.write("The error message given was: " + error.error_message + ".\n")
         exit(69)
 
+
+def diff_record(record_a, record_a_object, record_b, record_b_object):
+    compare_values = ["type", "ttl", "resource_records", "alias_hosted_zone_id", "alias_dns_name", "identifier", "weight", "region"]
+    diff_record_result = False
+
+    for value in compare_values:
+        if getattr(record, value) != getattr(to_zone_existing_resource_record_dict[record.name], value):
+            diff_record_result = True
+    return diff_record_result
+
 app_name = os.path.basename(__file__)
 config = ConfigParser.ConfigParser()
 config.read('config.ini')
-#functions: newzone, new account, newzone and newaccount
+#functions: currently supports newzone - the functions are set automatically by the route53-migrate-zone script
-functions = ["newzone", "newaccount"]
+functions = []
 
-#these user credentials should be read-only
+#the from_zone user credentials should be read-only
 from_access_key = config.get("from_zone_values", "from_access_key")
 from_secret_key = config.get("from_zone_values", "from_secret_key")
 from_zone_name = config.get("from_zone_values", "from_zone_name")
@@ -37,15 +47,17 @@ to_zone_name = config.get("to_zone_values", "to_zone_name")
 #best would be to retreive the to_zone_id using to_zone_name
 to_zone_id = config.get("to_zone_values", "to_zone_id")
 
+record_types_to_migrate = ["A", "CNAME", "MX", "TXT"]
+
+if from_zone_name != to_zone_name:
+    print app_name + " will rewrite domain names ending in \"" + from_zone_name + "\" to domain names ending in \"" + to_zone_name + "\""
+    functions.append("newzone")
+
 #creates Route53Connection Object
 from_connection = boto.route53.Route53Connection(aws_access_key_id=from_access_key, aws_secret_access_key=from_secret_key)
 to_connection = boto.route53.Route53Connection(aws_access_key_id=to_access_key, aws_secret_access_key=to_secret_key)
-#creates a set of changes to be delivered to Route53
-to_zone_record_changeset = boto.route53.record.ResourceRecordSets(to_connection, to_zone_id)
 
-record_types_to_migrate = ["A", "CNAME", "MX", "TXT"]
+#create connection to from_zone
-
-#print out all records
 try:
     from_zone = from_connection.get_zone(from_zone_name)
 except boto.route53.exception.DNSServerError, error:
@@ -53,9 +65,37 @@ except boto.route53.exception.DNSServerError, error:
     sys.stdout.write("The error message given was: " + error.error_message + ".\n")
     exit(1)
 
+#create connection to to_zone
+try:
+    to_zone = to_connection.get_zone(to_zone_name)
+except boto.route53.exception.DNSServerError, error:
+    sys.stdout.write("An error occured when attempting to create a connection to AWS.\n")
+    sys.stdout.write("The error message given was: " + error.error_message + ".\n")
+    exit(1)
+
+#creates ResourceRecordSets object named from_zone_records (ResourceRecordSets = a collection of resource records)
 from_zone_records = from_zone.get_records()
-#resource_record_dict will be used to store all resource records
+#creates ResourceRecordSets object named to_zone_records (ResourceRecordSets = a collection of resource records)
+to_zone_records = to_zone.get_records()
+
+#resource_record_dict will be used to store all resource records that should be transferred
 resource_record_dict = {}
+#to_zone_existing_resource_record_dict will be used to store all resource records that should be transferred
+to_zone_existing_resource_record_dict = {}
+
+#creates a set of changes to be delivered to Route53
+to_zone_record_changeset = boto.route53.record.ResourceRecordSets(to_connection, to_zone_id)
+
+for record in to_zone_records:
+    to_zone_existing_resource_record_dict[record.name] = record
+
+#counts of records - should be replaced by dictionary
+uncommitted_change_elements = 0
+processed_record_count = 0
+migrated_record_count = 0
+existing_records_in_to_zone_count = 0
+identical_records_in_to_zone_count = 0
+different_records_in_to_zone_count = 0
 
 #get records from from_zone
 for record in from_zone_records:
@@ -64,15 +104,25 @@ for record in from_zone_records:
             #print "Existing Record Name: " + record.name
             record.name = re.sub(from_zone_name, to_zone_name, record.name)
             #print "Modified Record Name: " + record.name
+        #test if record exists in to_zone
+        if record.name in to_zone_existing_resource_record_dict:
+            existing_records_in_to_zone_count += 1
+            #compare records in from_domain and to_domain, store result as diff_result
+            diff_result = diff_record(record.name, record, record.name, to_zone_existing_resource_record_dict)
+            if diff_result is True:
+                different_records_in_to_zone_count += 1
+                sys.stdout.write("Record \"" + record.name + "\" exists in both \"" + from_zone_name + "\" and \"" + to_zone_name + "\" and is different.\n")
+            elif diff_result is False:
+                identical_records_in_to_zone_count += 1
+                sys.stdout.write("Record \"" + record.name + "\" exists in both \"" + from_zone_name + "\" and \"" + to_zone_name + "\" and is identical.\n")
+            else:
+                sys.stdout.write("Diff of record " + record.name + " failed.\n")
+                exit(1)
+        else:
             resource_record_dict[record.name] = boto.route53.record.Record(name=record.name, type=record.type, ttl=record.ttl, resource_records=record.resource_records, alias_hosted_zone_id=record.alias_hosted_zone_id, alias_dns_name=record.alias_dns_name, identifier=record.identifier, weight=record.weight, region=record.region)
 
-#commit records to to_zone
-uncommitted_change_elements = 0
-examined_record_count = 0
-migrated_record_count = 0
-
 for record in resource_record_dict:
-    examined_record_count += 1
+    processed_record_count += 1
     #if record is an alias record we are not supporting yet
     if resource_record_dict[record].alias_dns_name is not None:
         sys.stdout.write("Record \"" + resource_record_dict[record].name + "\" is an alias record set and will not be migrated. " + app_name + " does not currently support alias record sets.\n")
@@ -82,7 +132,7 @@ for record in resource_record_dict:
     #DEBUG: print "Uncommitted Record Count:" + str(uncommitted_change_elements)
     #if there are 99 uncomitted change elements than they must be committed - Amazon only accepts up to 99 change elements at a given time
     #if the number of examined records is equal to the number of records then we can commit as well - we are now done examing records
-    if uncommitted_change_elements >= 99 or examined_record_count == len(resource_record_dict):
+    if uncommitted_change_elements >= 99 or processed_record_count == len(resource_record_dict):
         #DEBUG: print "Flushing Records:" + str(uncommitted_change_elements)
         commit_record_changeset(to_zone_record_changeset)
         migrated_record_count += uncommitted_change_elements
@@ -93,5 +143,8 @@ for record in resource_record_dict:
 print "Summary:"
 print "Records Migrated from zone: \"" + from_zone_name + "\" to zone: \"" + from_zone_name + "\"."
 print "Types of Records Selected for Migration: " + str(record_types_to_migrate) + "."
-print "Records Migrated: " + str(migrated_record_count) + "."
+print "Records processed (records such as Alias records may be processed but not migrated): " + str(processed_record_count)
-print "Records Examined: " + str(examined_record_count) + "."
+print "Records migrated: " + str(migrated_record_count) + "."
+print "Records not migrated because they already exist in zone \"" + to_zone_name + "\": " + str(existing_records_in_to_zone_count)
+print "Records that exist in both \"" + from_zone_name + "\" and \"" + to_zone_name + "\" and are identical: " + str(identical_records_in_to_zone_count)
+print "Records that exist in both \"" + from_zone_name + "\" and \"" + to_zone_name + "\" and are different: " + str(different_records_in_to_zone_count)