VPC Peering routes should be preserved if they don't change.

[marcin]

Describe the Feature

Current code for adding routes is based on count

terraform-aws-vpc-peering/main.tf

Lines 51 to 67 in 47c6e51

 # Create routes from requestor to acceptor 
 resource "aws_route" "requestor" { 
   count                     = module.this.enabled ? length(distinct(sort(data.aws_route_tables.requestor.0.ids))) * length(data.aws_vpc.acceptor.0.cidr_block_associations) : 0 
   route_table_id            = element(distinct(sort(data.aws_route_tables.requestor.0.ids)), ceil(count.index / length(data.aws_vpc.acceptor.0.cidr_block_associations))) 
   destination_cidr_block    = data.aws_vpc.acceptor.0.cidr_block_associations[count.index % length(data.aws_vpc.acceptor.0.cidr_block_associations)]["cidr_block"] 
   vpc_peering_connection_id = join("", aws_vpc_peering_connection.default.*.id) 
   depends_on                = [data.aws_route_tables.requestor, aws_vpc_peering_connection.default] 
 } 
  
 # Create routes from acceptor to requestor 
 resource "aws_route" "acceptor" { 
   count                     = module.this.enabled ? length(distinct(sort(data.aws_route_tables.acceptor.0.ids))) * length(data.aws_vpc.requestor.0.cidr_block_associations) : 0 
   route_table_id            = element(distinct(sort(data.aws_route_tables.acceptor.0.ids)), ceil(count.index / length(data.aws_vpc.requestor.0.cidr_block_associations))) 
   destination_cidr_block    = data.aws_vpc.requestor.0.cidr_block_associations[count.index % length(data.aws_vpc.requestor.0.cidr_block_associations)]["cidr_block"] 
   vpc_peering_connection_id = join("", aws_vpc_peering_connection.default.*.id) 
   depends_on                = [data.aws_route_tables.acceptor, aws_vpc_peering_connection.default] 
 } 

Changing tags can possible result in changing count order and removal of actually using peering routing.

Expected Behavior

If matching pattern tag for a route is changed then only associated route table for this exact peering should be changed.

Use Case

It's possible that downtime will happen during terraform apply when tags will be changed on route.

Describe Ideal Solution

aws_route inside this module should use for_each which would prevent temporary routing changes