Multicert http listener (#66)

* Adding SNI cert support

* Updated README.md

* adding default value

* adding default value

* adding default value

* Adding missing sni resource

* Updated README.md

* Fixing typo in reource reference

* Fixing typo in resource reference

* Fixing count reference

Co-authored-by: actions-bot <58130806+actions-bot@users.noreply.github.com>

README.md

@@ -64,8 +64,15 @@ We literally have [*hundreds of terraform modules*][terraform_modules] that are
 ## Usage
 
 
-**IMPORTANT:** The `master` branch is used in `source` just as an example. In your code, do not pin to `master` because there may be breaking changes between releases.
-Instead pin to the release tag (e.g. `?ref=tags/x.y.z`) of one of our [latest releases](https://github.com/cloudposse/terraform-aws-alb/releases).
+**IMPORTANT:** We do not pin modules to versions in our examples because of the
+difficulty of keeping the versions in the documentation in sync with the latest released versions.
+We highly recommend that in your code you pin the version to the exact version you are
+using so that your infrastructure remains stable, and update versions in a
+systematic way so that they do not catch you by surprise.
+
+Also, because of a bug in the Terraform registry ([hashicorp/terraform#21417](https://github.com/hashicorp/terraform/issues/21417)),
+the registry shows many of our inputs as required when in fact they are optional.
+The table below correctly indicates which inputs are required.
 
 
 For a complete example, see [examples/complete](examples/complete).

main.tf

@@ -172,3 +172,9 @@ resource "aws_lb_listener" "https" {
     type             = "forward"
   }
 }
+resource "aws_lb_listener_certificate" "https_sni" {
+  count           = module.this.enabled && var.https_enabled && var.additional_certs != [] ? length(var.additional_certs) : 0
+  listener_arn    = join("", aws_lb_listener.https.*.arn)
+  certificate_arn = var.additional_certs[count.index]
+}
+