Improve Troubleshooting Recommendations for Argument Not Found Errors

[bflad]

Current Terraform Version

v0.14.8

Use-cases

• When developing against an existing Terraform configuration which is pinned to older Terraform Provider versions, there can be arguments which are only available in newer Terraform Provider versions, e.g.

resource "example_thing" "example" {
  newer_attribute = "example"
}

• When developing a Terraform configuration using a Terraform Provider that has a Resource with multiple blocks, it is possible to incorrectly add an argument to the wrong nesting level, e.g.

resource "example_thing" "example" {
  block {
    # nested_attribute belongs here
  }

  nested_attribute = "example"
}

Both of these will currently generate a generic HCL error such as:

$ terraform plan
...
Error: Unsupported argument

on main.tf line ##, in resource "example_thing" "example":
34: newer_attribute = "example"

An argument named "newer_attribute" is not expected here.

Terraform CLI and Terraform Provider repositories will occasionally receive new GitHub issues relating to this when typically there are two helpful recommendations:

• Checking the provider version to ensure it is up to date
• Checking the resource documentation

For newer practitioners or those unfamiliar with why they might be receiving this error, it might be helpful to include some of this additional troubleshooting information with the error message.

Proposal

For resource arguments, catch and wrap the HCL error message with some additional Terraform context:

Error: Unsupported argument

on main.tf line ##, in resource "example_thing" "example":
34: newer_attribute = "example"

An argument named "newer_attribute" is not expected here. Use the resource documentation to verify that this resource supports this argument and that the provider version being used with this configuration is up to date with the expected resource functionality.

The same could theoretically be tailored and applied for provider arguments as well.

References

• instance_template/Instance_Group-GCP---on main.tf line 34, in resource "google_compute_region_instance_group_manager" "mig": 34: instance_template = google_compute_instance_template.template.self_link An argument named "instance_template" is not expected here. #28107
• project argument unexpected in google_storage_bucket_iam_member #27782
• Incorrect parameter name in policy_set_definition.policy_definition_reference #27478
• azurerm_hdinsight_kafka_cluster error - An argument named "min_tls_version" is not expected here. #27470
• Azure Windows Virtual Desktop: Unsupported argument "validation_environment" #26552
• Azure - azurerm_app_service - Unable to apply health_check_path in site_config #26256
  etc.

[bflad]

Given no 👍 interest or commentary, closing to reduce issue noise.