Duplicate Entries in TypeSet GetChange[during update]

Terraform Providers Plugin Development
1

I have a Terraform resource called test_resource with a nested TypeSet attribute called input_interface. Here’s an example configuration:

resource "test_resource" "example" {
  name = "example-resource"

  input_interface {
    name          = "interface-1"
    corr_id       = "corr-12345"
    legacy_ports  = [80, 443]
    enable_feature = true
    domains {
      name        = "test"
      auto_delete = true
    }
  }

  input_interface {
    name          = "interface-2"
    corr_id       = "corr-67890"
    legacy_ports  = [22]
    enable_feature = false
  }
}
  • input_interface is a TypeSet attribute.
  • Each input_interface has optional fields like legacy_ports and enable_feature.
  • The domains block is a nested structure with fields like name and auto_delete.

When Terraform processes this resource, it uses a hash function to uniquely identify each input_interface in the set. However, if the hash function doesn’t handle optional or computed fields correctly, it leads to inconsistent behavior in the GetChange function. call, often returning dummy and incomplete values.

When you update this resource, Terraform uses the GetChange function to compare the old and new states of the input_interface set. However, you might notice that the GetChange output contains incomplete or dummy values, such as:

  • Empty corr_id or name fields.
  • Missing or incomplete domains blocks.
  • Incorrect or partial legacy_ports values.

For example, the newList in GetChange might look like this

*Set(map[string]interface{}{
  "entry-1": map[string]interface{}{
    "name":          "interface-1",
    "corr_id":       "", // Empty or dummy value
    "legacy_ports":  []interface{}{}, // Empty or dummy value
    "enable_feature": false, // Incorrect value
    "domains":       []interface{}{}, // Missing or incomplete
  },
  "entry-2": map[string]interface{}{
    "name":          "interface-2",
    "corr_id":       "corr-67890",
    "legacy_ports":  []interface{}{22},
    "enable_feature": false,
    "domains":       []interface{}{}, // Missing or incomplete
  },
})