Module fails if ES service linked role doesn't exist

[joe-niland]

I found that this module wouldn't work unless I created the ES service linked role first (for service "es.amazonaws.com").

The reason for this is that if the role doesn't already exist the data source element fails (https://github.com/cloudposse/terraform-aws-elasticsearch/blob/master/main.tf#L68) and the module won't complete.

The create_iam_service_linked_role variable was added a while ago to deal with this issue, however it seems the variable value is not used.

Expected Behavior

The module should run even if the service linked role doesn't exist

Steps to Reproduce

1. Include this module, setting variable create_iam_service_linked_role to true
2. terraform apply

Environment (please complete the following information):

TF 0.12.21

[igable]

If anyone is looking for a workaround until this issue is resolved all you need to do is:

aws iam create-service-linked-role --aws-service-name es.amazonaws.com