Data source with computed value does not have attribute outputs

[hbuckle]

I suspect this is related to the already reported data source lifecycle issues but I couldn't see this use case exactly

Terraform Version

terraform -v
Terraform v0.11.8
+ provider.null v1.0.0
+ provider.random v2.0.0

Terraform Configuration Files

resource "random_string" "test" {
  length  = 6
  special = false
  upper   = false
}

data "null_data_source" "test" {
  count = 4

  inputs = {
    test = "${random_string.test.result}-${count.index}"
  }
}

resource "null_resource" "test" {
  count = 4

  triggers = {
    test = "${data.null_data_source.test.*.outputs.test[count.index]}"
  }
}

Output

terraform plan
Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.
------------------------------------------------------------------------
Error: Error running plan: 1 error(s) occurred:

* null_resource.test: 4 error(s) occurred:

* null_resource.test[2]: Resource 'data.null_data_source.test' does not have attribute 'outputs.test' for variable 'data.null_data_source.test.*.outputs.test'
* null_resource.test[3]: Resource 'data.null_data_source.test' does not have attribute 'outputs.test' for variable 'data.null_data_source.test.*.outputs.test'
* null_resource.test[0]: Resource 'data.null_data_source.test' does not have attribute 'outputs.test' for variable 'data.null_data_source.test.*.outputs.test'
* null_resource.test[1]: Resource 'data.null_data_source.test' does not have attribute 'outputs.test' for variable 'data.null_data_source.test.*.outputs.test'

If I replace ${random_string.test.result} in the data source input with a hardcoded string then the plan succeeds:

data "null_data_source" "test" {
  count = 4

  inputs = {
    test = "test-${count.index}"
  }
}

resource "null_resource" "test" {
  count = 4

  triggers = {
    test = "${data.null_data_source.test.*.outputs.test[count.index]}"
  }
}

terraform plan
Refreshing Terraform state in-memory prior to plan...
The refreshed state will be used to calculate this plan, but will not be
persisted to local or remote state storage.

data.null_data_source.test[0]: Refreshing state...
data.null_data_source.test[1]: Refreshing state...
data.null_data_source.test[2]: Refreshing state...
data.null_data_source.test[3]: Refreshing state...

------------------------------------------------------------------------

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  + null_resource.test[0]
      id:            <computed>
      triggers.%:    "1"
      triggers.test: "test-0"

  + null_resource.test[1]
      id:            <computed>
      triggers.%:    "1"
      triggers.test: "test-1"

  + null_resource.test[2]
      id:            <computed>
      triggers.%:    "1"
      triggers.test: "test-2"

  + null_resource.test[3]
      id:            <computed>
      triggers.%:    "1"
      triggers.test: "test-3"

[mildwonkey]

Hi @hbuckle,
Sorry you've come across this unexpected behavior. There are other tickets covering this, such as #17034, so I am going to close this one - please go give a 👍 on #17034!

[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 have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.