make change based on test result & review

Author: LingyuTang

internal/services/batch/batch_pool_resource.go

@@ -1551,7 +1551,7 @@ func startTaskSchema() map[string]*pluginsdk.Schema {
 							Schema: map[string]*pluginsdk.Schema{
 								"source": {
 									Type:         pluginsdk.TypeString,
-									Optional:     true,
+									Required:     true,
 									ValidateFunc: validation.StringInSlice(pool.PossibleValuesForContainerHostDataPath(), false),
 								},
 								"read_only_enabled": {

internal/services/batch/batch_pool_resource_test.go

@@ -298,6 +298,8 @@ func TestAccBatchPool_startTask_complete(t *testing.T) {
 				check.That(data.ResourceName).Key("start_task.0.container.0.working_directory").HasValue("ContainerImageDefault"),
 				check.That(data.ResourceName).Key("start_task.0.container.0.host_directory_mount.0.source").HasValue("Startup"),
 				check.That(data.ResourceName).Key("start_task.0.container.0.host_directory_mount.0.read_only_enabled").HasValue("false"),
+				check.That(data.ResourceName).Key("start_task.0.container.0.host_directory_mount.1.source").HasValue("Applications"),
+				check.That(data.ResourceName).Key("start_task.0.container.0.host_directory_mount.1.read_only_enabled").HasValue("true"),
 			),
 		},
 		data.ImportStep("stop_pending_resize_operation",
@@ -1259,7 +1261,10 @@ resource "azurerm_batch_pool" "test" {
       working_directory = "ContainerImageDefault"
       host_directory_mount {
         source            = "Startup"
-        read_only_enabled = false
+      }
+      host_directory_mount {
+        source            = "Applications"
+        read_only_enabled = true
       }
     }
 

website/docs/r/batch_pool.html.markdown

@@ -359,7 +359,7 @@ A `container_registries` block supports the following:
 
 A `host_directory_mount` block supports the following:
 
-* `source` - (Optional) The paths which will be mounted to container task's container. Possible values include `Applications`, `JobPrep`, `Shared`, `Startup`, `Task`, and `VfsMounts`.
+* `source` - (Required) The paths which will be mounted to container task's container. Possible values include `Applications`, `JobPrep`, `Shared`, `Startup`, `Task`, and `VfsMounts`.
 
 * `read_only_enabled` - (Optional) Mount this source path as read-only mode or not. Default to `false` (read/write mode).