Support moving from null_resource to terraform_data (#35163)

This change enables the built-in provider's `terraform_data` managed resource to work with the `moved` configuration block where the `from` address is a `null_resource` managed resource type from the official `hashicorp/null` provider. It produces no plan differences for typical configurations and specifically helps practitioners from re-running provisioners while moving resource types.

In addition to the unit testing, this was manually tested with the following configurations and outputs:

Initial configuration (no `triggers`):

```terraform
terraform {
  required_providers {
    null = {
      source  = "hashicorp/null"
      version = "3.2.2"
    }
  }
}

resource "null_resource" "example" {
  provisioner "local-exec" {
    command = "echo 'Hello, World!'"
  }
}
```

Moved configuration (no `triggers`):

```terraform
resource "terraform_data" "example" {
  provisioner "local-exec" {
    command = "echo 'Hello, World!'"
  }
}

moved {
  from = null_resource.example
  to   = terraform_data.example
}
```

Moved output (no `triggers`):

```console
$ terraform apply
terraform_data.example: Refreshing state... [id=892002337455008838]

Terraform will perform the following actions:

  # null_resource.example has moved to terraform_data.example
    resource "terraform_data" "example" {
        id = "892002337455008838"
    }

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

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

Apply complete! Resources: 0 added, 0 changed, 0 destroyed.
```

Initial configuration (with `triggers`):

```terraform
terraform {
  required_providers {
    null = {
      source  = "hashicorp/null"
      version = "3.2.2"
    }
  }
}

resource "null_resource" "example" {
  triggers = {
    examplekey = "examplevalue"
  }

  provisioner "local-exec" {
    command = "echo 'Hello, World!'"
  }
}
```

Moved configuration (with `triggers`):

```terraform
resource "terraform_data" "example" {
  triggers_replace = {
    examplekey = "examplevalue"
  }

  provisioner "local-exec" {
    command = "echo 'Hello, World!'"
  }
}

moved {
  from = null_resource.example
  to   = terraform_data.example
}
```

Moved output (with `triggers`):

```console
$ terraform apply
terraform_data.example: Refreshing state... [id=1651348367769440250]

Terraform will perform the following actions:

  # null_resource.example has moved to terraform_data.example
    resource "terraform_data" "example" {
        id               = "1651348367769440250"
        # (1 unchanged attribute hidden)
    }

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

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

Apply complete! Resources: 0 added, 0 changed, 0 destroyed.
```

internal/builtin/providers/terraform/provider.go

@@ -23,6 +23,9 @@ func NewProvider() providers.Interface {
 // GetSchema returns the complete schema for the provider.
 func (p *Provider) GetProviderSchema() providers.GetProviderSchemaResponse {
 	return providers.GetProviderSchemaResponse{
+		ServerCapabilities: providers.ServerCapabilities{
+			MoveResourceState: true,
+		},
 		DataSources: map[string]providers.Schema{
 			"terraform_remote_state": dataSourceRemoteStateGetSchema(),
 		},
@@ -169,10 +172,18 @@ func (p *Provider) ImportResourceState(req providers.ImportResourceStateRequest)
 	panic("unimplemented - terraform_remote_state has no resources")
 }
 
-func (p *Provider) MoveResourceState(providers.MoveResourceStateRequest) providers.MoveResourceStateResponse {
-	// We don't expose the move_resource_state capability, so this should never
-	// be called.
-	panic("unimplemented - terraform.io/builtin/terraform does not support cross-resource moves")
+// MoveResourceState requests that the given resource be moved.
+func (p *Provider) MoveResourceState(req providers.MoveResourceStateRequest) providers.MoveResourceStateResponse {
+	switch req.TargetTypeName {
+	case "terraform_data":
+		return moveDataStoreResourceState(req)
+	default:
+		var resp providers.MoveResourceStateResponse
+
+		resp.Diagnostics = resp.Diagnostics.Append(fmt.Errorf("Error: unsupported resource %s", req.TargetTypeName))
+
+		return resp
+	}
 }
 
 // ValidateResourceConfig is used to to validate the resource configuration values.

internal/builtin/providers/terraform/provider_test.go

@@ -4,10 +4,66 @@
 package terraform
 
 import (
+	"testing"
+
 	backendInit "github.com/hashicorp/terraform/internal/backend/init"
+	"github.com/hashicorp/terraform/internal/providers"
+	"github.com/zclconf/go-cty/cty"
+	ctyjson "github.com/zclconf/go-cty/cty/json"
 )
 
 func init() {
 	// Initialize the backends
 	backendInit.Init(nil)
 }
+
+func TestMoveResourceState_DataStore(t *testing.T) {
+	t.Parallel()
+
+	nullResourceStateValue := cty.ObjectVal(map[string]cty.Value{
+		"id": cty.StringVal("test"),
+	})
+	nullResourceStateJSON, err := ctyjson.Marshal(nullResourceStateValue, nullResourceStateValue.Type())
+
+	if err != nil {
+		t.Fatalf("failed to marshal null resource state: %s", err)
+	}
+
+	provider := &Provider{}
+	req := providers.MoveResourceStateRequest{
+		SourceProviderAddress: "registry.terraform.io/hashicorp/null",
+		SourceStateJSON:       nullResourceStateJSON,
+		SourceTypeName:        "null_resource",
+		TargetTypeName:        "terraform_data",
+	}
+	resp := provider.MoveResourceState(req)
+
+	if resp.Diagnostics.HasErrors() {
+		t.Errorf("unexpected diagnostics: %s", resp.Diagnostics.Err())
+	}
+
+	expectedTargetState := cty.ObjectVal(map[string]cty.Value{
+		"id":               cty.StringVal("test"),
+		"input":            cty.NullVal(cty.DynamicPseudoType),
+		"output":           cty.NullVal(cty.DynamicPseudoType),
+		"triggers_replace": cty.NullVal(cty.DynamicPseudoType),
+	})
+
+	if !resp.TargetState.RawEquals(expectedTargetState) {
+		t.Errorf("expected state was:\n%#v\ngot state is:\n%#v\n", expectedTargetState, resp.TargetState)
+	}
+}
+
+func TestMoveResourceState_NonExistentResource(t *testing.T) {
+	t.Parallel()
+
+	provider := &Provider{}
+	req := providers.MoveResourceStateRequest{
+		TargetTypeName: "nonexistent_resource",
+	}
+	resp := provider.MoveResourceState(req)
+
+	if !resp.Diagnostics.HasErrors() {
+		t.Fatal("expected diagnostics")
+	}
+}

internal/builtin/providers/terraform/resource_data.go

@@ -5,6 +5,7 @@ package terraform
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/hashicorp/go-uuid"
 	"github.com/hashicorp/terraform/internal/configs/configschema"
@@ -170,3 +171,84 @@ func importDataStore(req providers.ImportResourceStateRequest) (resp providers.I
 	}
 	return resp
 }
+
+// moveDataStoreResourceState enables moving from the official null_resource
+// managed resource to the terraform_data managed resource.
+func moveDataStoreResourceState(req providers.MoveResourceStateRequest) (resp providers.MoveResourceStateResponse) {
+	// Verify that the source provider is an official hashicorp/null provider,
+	// but ignore the hostname for mirrors.
+	if !strings.HasSuffix(req.SourceProviderAddress, "hashicorp/null") {
+		diag := tfdiags.Sourceless(
+			tfdiags.Error,
+			"Unsupported source provider for move operation",
+			"Only moving from the official hashicorp/null provider to terraform_data is supported.",
+		)
+		resp.Diagnostics = resp.Diagnostics.Append(diag)
+
+		return resp
+	}
+
+	// Verify that the source resource type name is null_resource.
+	if req.SourceTypeName != "null_resource" {
+		diag := tfdiags.Sourceless(
+			tfdiags.Error,
+			"Unsupported source resource type for move operation",
+			"Only moving from the null_resource managed resource to terraform_data is supported.",
+		)
+		resp.Diagnostics = resp.Diagnostics.Append(diag)
+
+		return resp
+	}
+
+	nullResourceSchemaType := nullResourceSchema().Block.ImpliedType()
+	nullResourceValue, err := ctyjson.Unmarshal(req.SourceStateJSON, nullResourceSchemaType)
+
+	if err != nil {
+		resp.Diagnostics = resp.Diagnostics.Append(err)
+
+		return resp
+	}
+
+	triggersReplace := nullResourceValue.GetAttr("triggers")
+
+	// PlanResourceChange uses RawEquals comparison, which will show a
+	// difference between cty.NullVal(cty.Map(cty.String)) and
+	// cty.NullVal(cty.DynamicPseudoType).
+	if triggersReplace.IsNull() {
+		triggersReplace = cty.NullVal(cty.DynamicPseudoType)
+	} else {
+		// PlanResourceChange uses RawEquals comparison, which will show a
+		// difference between cty.MapVal(...) and cty.ObjectVal(...). Given that
+		// triggers is typically configured using direct configuration syntax of
+		// {...}, which is a cty.ObjectVal, over a map typed variable or
+		// explicitly type converted map, this pragmatically chooses to convert
+		// the triggers value to cty.ObjectVal to prevent an immediate plan
+		// difference for the more typical case.
+		triggersReplace = cty.ObjectVal(triggersReplace.AsValueMap())
+	}
+
+	schema := dataStoreResourceSchema()
+	v := cty.ObjectVal(map[string]cty.Value{
+		"id":               nullResourceValue.GetAttr("id"),
+		"triggers_replace": triggersReplace,
+	})
+
+	state, err := schema.Block.CoerceValue(v)
+
+	// null_resource did not use private state, so it is unnecessary to move.
+	resp.Diagnostics = resp.Diagnostics.Append(err)
+	resp.TargetState = state
+
+	return resp
+}
+
+func nullResourceSchema() providers.Schema {
+	return providers.Schema{
+		Block: &configschema.Block{
+			Attributes: map[string]*configschema.Attribute{
+				"id":       {Type: cty.String, Computed: true},
+				"triggers": {Type: cty.Map(cty.String), Optional: true},
+			},
+		},
+	}
+}

internal/builtin/providers/terraform/resource_data_test.go

@@ -383,3 +383,108 @@ func TestManagedDataApply(t *testing.T) {
 		})
 	}
 }
+
+func TestMoveDataStoreResourceState_Id(t *testing.T) {
+	t.Parallel()
+
+	nullResourceStateValue := cty.ObjectVal(map[string]cty.Value{
+		"id":       cty.StringVal("test"),
+		"triggers": cty.NullVal(cty.Map(cty.String)),
+	})
+	nullResourceStateJSON, err := ctyjson.Marshal(nullResourceStateValue, nullResourceStateValue.Type())
+
+	if err != nil {
+		t.Fatalf("failed to marshal null resource state: %s", err)
+	}
+
+	req := providers.MoveResourceStateRequest{
+		SourceProviderAddress: "registry.terraform.io/hashicorp/null",
+		SourceStateJSON:       nullResourceStateJSON,
+		SourceTypeName:        "null_resource",
+		TargetTypeName:        "terraform_data",
+	}
+	resp := moveDataStoreResourceState(req)
+
+	if resp.Diagnostics.HasErrors() {
+		t.Errorf("unexpected diagnostics: %s", resp.Diagnostics.Err())
+	}
+
+	expectedTargetState := cty.ObjectVal(map[string]cty.Value{
+		"id":               cty.StringVal("test"),
+		"input":            cty.NullVal(cty.DynamicPseudoType),
+		"output":           cty.NullVal(cty.DynamicPseudoType),
+		"triggers_replace": cty.NullVal(cty.DynamicPseudoType),
+	})
+
+	if !resp.TargetState.RawEquals(expectedTargetState) {
+		t.Errorf("expected state was:\n%#v\ngot state is:\n%#v\n", expectedTargetState, resp.TargetState)
+	}
+}
+
+func TestMoveResourceState_SourceProviderAddress(t *testing.T) {
+	t.Parallel()
+
+	req := providers.MoveResourceStateRequest{
+		SourceProviderAddress: "registry.terraform.io/examplecorp/null",
+	}
+	resp := moveDataStoreResourceState(req)
+
+	if !resp.Diagnostics.HasErrors() {
+		t.Fatal("expected diagnostics")
+	}
+}
+
+func TestMoveResourceState_SourceTypeName(t *testing.T) {
+	t.Parallel()
+
+	req := providers.MoveResourceStateRequest{
+		SourceProviderAddress: "registry.terraform.io/hashicorp/null",
+		SourceTypeName:        "null_data_source",
+	}
+	resp := moveDataStoreResourceState(req)
+
+	if !resp.Diagnostics.HasErrors() {
+		t.Fatal("expected diagnostics")
+	}
+}
+
+func TestMoveDataStoreResourceState_Triggers(t *testing.T) {
+	t.Parallel()
+
+	nullResourceStateValue := cty.ObjectVal(map[string]cty.Value{
+		"id": cty.StringVal("test"),
+		"triggers": cty.MapVal(map[string]cty.Value{
+			"testkey": cty.StringVal("testvalue"),
+		}),
+	})
+	nullResourceStateJSON, err := ctyjson.Marshal(nullResourceStateValue, nullResourceStateValue.Type())
+
+	if err != nil {
+		t.Fatalf("failed to marshal null resource state: %s", err)
+	}
+
+	req := providers.MoveResourceStateRequest{
+		SourceProviderAddress: "registry.terraform.io/hashicorp/null",
+		SourceStateJSON:       nullResourceStateJSON,
+		SourceTypeName:        "null_resource",
+		TargetTypeName:        "terraform_data",
+	}
+	resp := moveDataStoreResourceState(req)
+
+	if resp.Diagnostics.HasErrors() {
+		t.Errorf("unexpected diagnostics: %s", resp.Diagnostics.Err())
+	}
+
+	expectedTargetState := cty.ObjectVal(map[string]cty.Value{
+		"id":     cty.StringVal("test"),
+		"input":  cty.NullVal(cty.DynamicPseudoType),
+		"output": cty.NullVal(cty.DynamicPseudoType),
+		"triggers_replace": cty.ObjectVal(map[string]cty.Value{
+			"testkey": cty.StringVal("testvalue"),
+		}),
+	})
+
+	if !resp.TargetState.RawEquals(expectedTargetState) {
+		t.Errorf("expected state was:\n%#v\ngot state is:\n%#v\n", expectedTargetState, resp.TargetState)
+	}
+}