azurerm_postgresql_flexible_server: fix storage_tier calculation

internal/services/postgres/postgresql_flexible_server_resource.go

@@ -414,6 +414,20 @@ func resourcePostgresqlFlexibleServer() *pluginsdk.Resource {
 			}
 
 			if !isValid {
+				if strings.EqualFold(oldTierRaw.(string), newTier) {
+					// The tier value did not change, so we need to determin if they are
+					// using the default value for the tier, or they actually defined the
+					// tier in the config or not... If they did not define
+					// the tier in the config we need to assign a new valid default
+					// tier for the newMb value. However, if the tier is in the config
+					// this is a valid error and should be returned...
+					if v := diff.GetRawConfig().AsValueMap()["storage_tier"]; v.IsNull() {
+						diff.SetNew("storage_tier", string(storageTiers.DefaultTier))
+						log.Printf("[DEBUG]: 'storage_tier' was not valid and was not in the config assigning new default 'storage_tier' %q -> %q\n", newTier, storageTiers.DefaultTier)
+						return nil
+					}
+				}
+
 				return fmt.Errorf("invalid 'storage_tier' %q for defined 'storage_mb' size '%d', expected one of [%s]", newTier, newMb, azure.QuotedStringSlice(*storageTiers.ValidTiers))
 			}
 

internal/services/postgres/postgresql_flexible_server_resource_test.go

@@ -524,6 +524,65 @@ func TestAccPostgresqlFlexibleServer_invalidStorageTierScalingStorageMbStorageTi
 	})
 }
 
+func TestAccPostgresqlFlexibleServer_updateOnlyWithStorageMb(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_postgresql_flexible_server", "test")
+	r := PostgresqlFlexibleServerResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.invalidStorageTierScaling(data, "P4", "32768"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("administrator_password", "create_mode"),
+		{
+			Config: r.updateOnlyWithStorageMb(data, "65536"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+	})
+}
+
+func TestAccPostgresqlFlexibleServer_updateOnlyWithStorageTier(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_postgresql_flexible_server", "test")
+	r := PostgresqlFlexibleServerResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.invalidStorageTierScaling(data, "P4", "32768"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("administrator_password", "create_mode"),
+		{
+			Config: r.updateOnlyWithStorageTier(data, "P10"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("administrator_password", "create_mode"),
+		{
+			Config: r.updateStorageTierWithoutProperty(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				// the storage tier is not changed to the default value, because p10 is still valid.
+				check.That(data.ResourceName).Key("storage_tier").HasValue("P10"),
+			),
+		},
+		data.ImportStep("administrator_password", "create_mode"),
+		{
+			Config: r.updateOnlyWithStorageMb(data, "262144"),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+				check.That(data.ResourceName).Key("storage_tier").HasValue("P15"),
+			),
+		},
+	})
+}
+
 func (PostgresqlFlexibleServerResource) Exists(ctx context.Context, clients *clients.Client, state *pluginsdk.InstanceState) (*bool, error) {
 	id, err := servers.ParseFlexibleServerID(state.ID)
 	if err != nil {
@@ -551,6 +610,58 @@ resource "azurerm_resource_group" "test" {
 `, data.RandomInteger, data.Locations.Primary)
 }
 
+func (r PostgresqlFlexibleServerResource) updateOnlyWithStorageTier(data acceptance.TestData, storageTier string) string {
+	return fmt.Sprintf(`
+%s
+resource "azurerm_postgresql_flexible_server" "test" {
+  name                   = "acctest-fs-%d"
+  resource_group_name    = azurerm_resource_group.test.name
+  location               = azurerm_resource_group.test.location
+  administrator_login    = "adminTerraform"
+  administrator_password = "QAZwsx123"
+  storage_mb             = 65536
+  storage_tier           = "%s"
+  version                = "12"
+  sku_name               = "GP_Standard_D2s_v3"
+  zone                   = "2"
+}
+`, r.template(data), data.RandomInteger, storageTier)
+}
+
+func (r PostgresqlFlexibleServerResource) updateStorageTierWithoutProperty(data acceptance.TestData) string {
+	return fmt.Sprintf(`
+%s
+resource "azurerm_postgresql_flexible_server" "test" {
+  name                   = "acctest-fs-%d"
+  resource_group_name    = azurerm_resource_group.test.name
+  location               = azurerm_resource_group.test.location
+  administrator_login    = "adminTerraform"
+  administrator_password = "QAZwsx123"
+  storage_mb             = 65536
+  version                = "12"
+  sku_name               = "GP_Standard_D2s_v3"
+  zone                   = "2"
+}
+`, r.template(data), data.RandomInteger)
+}
+
+func (r PostgresqlFlexibleServerResource) updateOnlyWithStorageMb(data acceptance.TestData, storageMb string) string {
+	return fmt.Sprintf(`
+%s
+resource "azurerm_postgresql_flexible_server" "test" {
+  name                   = "acctest-fs-%d"
+  resource_group_name    = azurerm_resource_group.test.name
+  location               = azurerm_resource_group.test.location
+  administrator_login    = "adminTerraform"
+  administrator_password = "QAZwsx123"
+  storage_mb             = %s
+  version                = "12"
+  sku_name               = "GP_Standard_D2s_v3"
+  zone                   = "2"
+}
+`, r.template(data), data.RandomInteger, storageMb)
+}
+
 func (r PostgresqlFlexibleServerResource) basic(data acceptance.TestData) string {
 	return fmt.Sprintf(`
 %s