Optional/Computed attributes

[ewbankkit]

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• The resources and data sources in this provider are generated from the CloudFormation schema, so they can only support the actions that the underlying schema supports. For this reason submitted bugs should be limited to defects in the generation and runtime code of the provider. Customizing behavior of the resource, or noting a gap in behavior are not valid bugs and should be submitted as enhancements to AWS via the Cloudformation Open Coverage Roadmap.

There are attributes that are currently marked as Optional: true, Computed: false which are in reality Optional: true, Computed: true.
An example is the awscc_athena_workgroup's work_group_configuration attributes.
When not specified on creation, AWS defines values and returns them on resource read:

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

  # awscc_athena_work_group.test will be updated in-place
  ~ resource "awscc_athena_work_group" "test" {
        id                       = "awscc-testing"
        name                     = "awscc-testing"
      - state                    = "ENABLED" -> null
        tags                     = [
            {          },
        ]
      - work_group_configuration = {
        - enforce_work_group_configuration   = true -> null
        - engine_version                     = {
          - effective_engine_version = "Athena engine version 2" -> null
          - selected_engine_version  = "AUTO" -> null
        }
        - publish_cloudwatch_metrics_enabled = true -> null
        - requester_pays_enabled             = false -> null
      }
        # (1 unchanged attribute hidden)
    }

Plan: 0 to add, 1 to change, 0 to destroy.

In the CloudFormation resource schema, WorkGroupConfiguration is correctly not listed as either required or readOnly so the Terraform resource schema code generator only emits Computed: true.
This could be solved by specifying default values in the CFN schema or by having some other way of signaling that a property is optional but a value will then be determined for you.

[ewbankkit]

The JSON Schema default keyword is not required so AWS will not always specify the attributes' default values.

[ewbankkit]

Related:

• resource/awscc_lambda_function: Immediate Plan After Creation #220
• awscc_lambda_function keeps wanting to update properties (which then also fails) #185
• vpc default values do not persist after create() #301

[breathingdust]

After reviewing this issue with the AWS Cloud Control team we will change the provider generation code to mark all optional attributes with no defaults specified as Optional/Computed. This will prevent diffs from showing where an unspecified default value is applied and no value is set by the practioner.