Suppress diffs in the Fleet block between null vs {} vs {project = ""} (#13512) (#9726)

[upstream:a00e8fa9ad0c2b62821e8c512ee341e19cbf15a3]

Signed-off-by: Modular Magician <magic-modules@google.com>

Author: modular-magician

google-beta/services/container/resource_container_cluster.go

@@ -123,10 +123,20 @@ var (
 	})
 
 	suppressDiffForPreRegisteredFleet = schema.SchemaDiffSuppressFunc(func(k, oldValue, newValue string, d *schema.ResourceData) bool {
+		// Suppress if the cluster has been pre registered to fleet.
 		if v, _ := d.Get("fleet.0.pre_registered").(bool); v {
 			log.Printf("[DEBUG] fleet suppress pre_registered: %v\n", v)
 			return true
 		}
+		// Suppress the addition of a fleet block (count changes 0 -> 1) if the "project" field being added is null or empty.
+		if k == "fleet.#" && oldValue == "0" && newValue == "1" {
+			// When transitioning from 0->1 blocks, d.Get/d.GetOk effectively reads the 'new' config value.
+			projectVal, projectIsSet := d.GetOk("fleet.0.project")
+			if !projectIsSet || projectVal.(string) == "" {
+				log.Printf("[DEBUG] Suppressing diff for 'fleet.#' (0 -> 1) because fleet.0.project is null or empty in config.\n")
+				return true
+			}
+		}
 		return false
 	})
 )

google-beta/services/container/resource_container_cluster_test.go

@@ -5480,6 +5480,15 @@ func TestAccContainerCluster_withFleetConfig(t *testing.T) {
 				ImportStateVerify:       true,
 				ImportStateVerifyIgnore: []string{"deletion_protection"},
 			},
+			{
+				Config: testAccContainerCluster_WithEmptyFleetProject(clusterName, networkName, subnetworkName),
+			},
+			{
+				ResourceName:            "google_container_cluster.primary",
+				ImportState:             true,
+				ImportStateVerify:       true,
+				ImportStateVerifyIgnore: []string{"deletion_protection"},
+			},
 		},
 	})
 }
@@ -5584,6 +5593,24 @@ resource "google_container_cluster" "primary" {
 `, resource_name, networkName, subnetworkName)
 }
 
+func testAccContainerCluster_WithEmptyFleetProject(resource_name, networkName, subnetworkName string) string {
+	return fmt.Sprintf(`
+resource "google_container_cluster" "primary" {
+  name               = "%s"
+  location           = "us-central1-a"
+  initial_node_count = 1
+
+  fleet {
+    project = ""
+  }
+  network    = "%s"
+  subnetwork = "%s"
+
+  deletion_protection = false
+}
+`, resource_name, networkName, subnetworkName)
+}
+
 func testAccContainerCluster_withIncompatibleMasterVersionNodeVersion(name string) string {
 	return fmt.Sprintf(`
 resource "google_container_cluster" "gke_cluster" {