resource/aws_lb: suppress diff for attributes incorrect lb types

[appilon]

Fix #4011

We recently added support for all elbv2 load balancer attributes. Some attributes can only be applied to application load balancers and some only for network load balancers. Even though the code is correct and we would never attempt to set an attribute that didn't apply to a network load balancer (or vice versa), the shared nature of the schema for this resource (and it's defaults) would show values in the state plan even if it did not make sense for the type.

This PR will suppress the diff for the respective attributes and load balancer types. Please let me know if unit tests are required, I have pasted a capture of terraform plan to confirm the attribute are hidden based on type.

network.tf:

resource "aws_lb" "my-lb" {
  name_prefix        = "my-lb"
  load_balancer_type = "network"
}

terraform plan:

Terraform will perform the following actions:

  + aws_lb.my-lb
      id:                               <computed>
      arn:                              <computed>
      arn_suffix:                       <computed>
      dns_name:                         <computed>
      enable_cross_zone_load_balancing: "false"
      enable_deletion_protection:       "false"
      internal:                         <computed>
      ip_address_type:                  <computed>
      load_balancer_type:               "network"
      name:                             <computed>
      name_prefix:                      "my-lb"
      security_groups.#:                <computed>
      subnet_mapping.#:                 <computed>
      subnets.#:                        <computed>
      vpc_id:                           <computed>
      zone_id:                          <computed>

application.tf:

resource "aws_lb" "my-lb" {
  name_prefix        = "my-lb"
  load_balancer_type = "application"
}

terraform plan:

+ aws_lb.my-lb
      id:                         <computed>
      access_logs.#:              <computed>
      arn:                        <computed>
      arn_suffix:                 <computed>
      dns_name:                   <computed>
      enable_deletion_protection: "false"
      enable_http2:               "true"
      idle_timeout:               "60"
      internal:                   <computed>
      ip_address_type:            <computed>
      load_balancer_type:         "application"
      name:                       <computed>
      name_prefix:                "my-lb"
      security_groups.#:          <computed>
      subnet_mapping.#:           <computed>
      subnets.#:                  <computed>
      vpc_id:                     <computed>
      zone_id:                    <computed>

[tpickett66]

Thanks for jumping on this, I didn't realize that the output I was seeing wouldn't actually get applied since it wasn't applicable for the network type.

[appilon]

No worries @tpickett66 thank you for pointing out the erroneous diff, it's very important that the user experience is clear. From your point of view it is very worrisome that the plan appears to be applying attributes that don't make sense for the load balancer type.

[bflad]

LGTM -- thanks for this!! 🚀

[bflad]

This has been released in version 1.14.0 of the AWS provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!