This value does not have any attributes error while trying to use COS HMAC credentials in Terraform?

I am trying to use HMAC credentials for Cloud Object Storage/S3 in Terraform but seeing this error.

Error: Unsupported attribute

  on main.tf line 56, in resource "ibm_cos_bucket" "sink_bucket":
  56:       ACCESS_KEY               = ibm_resource_key.cos_key.credentials.cos_hmac_keys.access_key_id

This value does not have any attributes.


Error: Unsupported attribute

  on main.tf line 57, in resource "ibm_cos_bucket" "sink_bucket":
  57:       SECRET_ACCESS_KEY        = ibm_resource_key.cos_key.credentials.cos_hmac_keys.secret_access_key

This value does not have any attributes.

I have generated COS HMAC credentials by setting HMAC=true while creating the cos_key

resource ibm_resource_key cos_key {
  name                 = "${var.basename}-cos-key"
  resource_instance_id = ibm_resource_instance.cos.id
  role                 = "Writer"

  parameters = {
    service-endpoints = "private"
    HMAC = true
  }
}

When I check the terraform.tstate file, I see the credentials as below

"cos_key": {
      "value": {
        "credentials": {
          "apikey": "muydB9TyqWr9_aCmFlSRSu-JG3J3PPzXcxxxxxxx",
          "cos_hmac_keys.access_key_id": "e0892b46cfe1411cxxxxxx0",
          "cos_hmac_keys.secret_access_key": "8520aca8680e3e930f74a8869xxxxxx8a27a6",
          ...
          }
        }
      }

This is what worked for me

provisioner "local-exec" {
    command = "echo 'Credentials for MINIO client...'"
    environment = {
      ACCESS_KEY               = ibm_resource_key.cos_key.credentials["cos_hmac_keys.access_key_id"]
      SECRET_ACCESS_KEY        = ibm_resource_key.cos_key.credentials["cos_hmac_keys.secret_access_key"]
      COS_REGION               = var.region
      COS_BUCKET_NAME          = ibm_cos_bucket.sink_bucket.bucket_name
    }
  }

The problem here is custom json properties that inclue dots(.)like cos_hmac_keys.access_key_id. Terraform throws error until you use the below notation

credentials["cos_hmac_keys.access_key_id"]