Use TF Diff Attributes to set diff response changes when SkipDetailedDiffForChanges feature flag is set

internal/testprovider/schema.go

@@ -880,3 +880,21 @@ func AssertProvider(f func(data *schemav2.ResourceData)) *schemav2.Provider {
 		},
 	}
 }
+
+func CustomizedDiffProvider(f func(data *schemav2.ResourceData)) *schemav2.Provider {
+	return &schemav2.Provider{
+		Schema: map[string]*schemav2.Schema{},
+		ResourcesMap: map[string]*schemav2.Resource{
+			"test_resource": {
+				Schema: map[string]*schemav2.Schema{
+					"labels": {Type: schemav2.TypeString, Optional: true, Computed: true},
+				},
+				SchemaVersion: 1,
+				CustomizeDiff: func(ctx context.Context, diff *schemav2.ResourceDiff, i interface{}) error {
+					err := diff.SetNew("labels", "1")
+					return err
+				},
+			},
+		},
+	}
+}

pkg/tfbridge/info.go

@@ -128,6 +128,11 @@ type ProviderInfo struct {
 	//
 	// See also: pulumi/pulumi-terraform-bridge#1448
 	SkipValidateProviderConfigForPluginFramework bool
+
+	// Disables using detailed diff to determine diff changes and falls back on the length of TF Diff Attributes.
+	//
+	// See https://github.com/pulumi/pulumi-terraform-bridge/issues/1501
+	XSkipDetailedDiffForChanges bool
 }
 
 // Send logs or status logs to the user.

pkg/tfbridge/provider.go

@@ -661,6 +661,17 @@ func (p *Provider) Diff(ctx context.Context, req *pulumirpc.DiffRequest) (*pulum
 	doIgnoreChanges(ctx, res.TF.Schema(), res.Schema.Fields, olds, news, req.GetIgnoreChanges(), diff)
 	detailedDiff, changes := makeDetailedDiff(ctx, res.TF.Schema(), res.Schema.Fields, olds, news, diff)
 
+	// There are some providers/situations which `makeDetailedDiff` distorts the expected changes, leading
+	// to changes being dropped by Pulumi.
+	// Until we fix `makeDetailedDiff`, it is safer to refer to the Terraform Diff attribute length for setting
+	// the DiffResponse.
+	// We will still use `detailedDiff` for diff display purposes.
+
+	// See also https://github.com/pulumi/pulumi-terraform-bridge/issues/1501.
+	if p.info.XSkipDetailedDiffForChanges && len(diff.Attributes()) > 0 {
+		changes = pulumirpc.DiffResponse_DIFF_SOME
+	}
+
 	// If there were changes in this diff, check to see if we have a replacement.
 	var replaces []string
 	var replaced map[string]bool

pkg/tfbridge/provider_test.go

@@ -1793,6 +1793,44 @@ func TestTransformOutputs(t *testing.T) {
 	})
 }
 
+func TestSkipDetailedDiff(t *testing.T) {
+	provider := func(t *testing.T) *Provider {
+		p := testprovider.CustomizedDiffProvider(func(data *schema.ResourceData) {})
+		return &Provider{
+			tf:     shimv2.NewProvider(p),
+			config: shimv2.NewSchemaMap(p.Schema),
+			resources: map[tokens.Type]Resource{
+				"TestResource": {
+					TF:     shimv2.NewResource(p.ResourcesMap["test_resource"]),
+					TFName: "test_resource",
+					Schema: &ResourceInfo{
+						Tok: "TestResource",
+					},
+				},
+			},
+			info: ProviderInfo{
+				XSkipDetailedDiffForChanges: true,
+			},
+		}
+	}
+	t.Run("Diff", func(t *testing.T) {
+		testutils.Replay(t, provider(t), `
+                {
+		  "method": "/pulumirpc.ResourceProvider/Diff",
+		  "request": {
+		    "id": "0",
+		    "urn": "urn:pulumi:dev::teststack::TestResource::exres",
+		    "olds": {},
+		    "news": {}
+		  },
+		  "response": {
+		    "changes": "DIFF_SOME",
+		    "hasDetailedDiff": true
+		  }
+		}`)
+	})
+}
+
 func TestTransformFromState(t *testing.T) {
 	provider := func(t *testing.T) *Provider {
 		p := testprovider.AssertProvider(func(data *schema.ResourceData) {