[Yandex Cloud documentation](../../../index.md) > [Yandex Cloud Functions](../../index.md) > [Step-by-step guides](../index.md) > Managing a function > Mounting external resources to a function file system > Mounting buckets

# Mounting buckets to a function

You can mount Yandex Object Storage [buckets](../../../storage/concepts/bucket.md) to a function. Mounting a bucket automatically creates a new function [version](../../concepts/function.md#version).

To mount buckets to a function:

{% list tabs group=instructions %}

- Management console {#console}

  1. In the [management console](https://console.yandex.cloud), navigate to the folder containing the function.
  1. Navigate to **Cloud Functions**.
  1. Select the function.
  1. Navigate to the **Editor** tab.
  1. In the **Parameters** section, select or create a [service account](../../../iam/concepts/users/service-accounts.md) with one of these roles:
     * [`storage.viewer`](../../../storage/security/index.md#storage-viewer) to only read data from the mounted [bucket](../../../storage/concepts/bucket.md).
     * [`storage.uploader`](../../../storage/security/index.md#storage-uploader) to read and write data from/to the mounted bucket.
  1. Expand **Additional settings**.
  1. Under **Mounted buckets**:
  
      1. Click **Add bucket**.
      1. Specify the following:

          * **Mount point**: Name of the mount point. The directory with the mounted bucket will be accessible at `/function/storage/<mount_point>`.
          * **Bucket**: Bucket you want to mount. If necessary, [create](../../../storage/operations/buckets/create.md) a new bucket.
          * **Directory**: Bucket [folder](../../../storage/concepts/object.md#folder) that will be mounted to the container. Leave this field empty to mount the entire bucket.
      1. Enable **Read-only** to prevent writing to the bucket. With this option enabled, data from the mounted bucket will be read-only.

      To mount an additional bucket to the function, click **Add bucket** again and configure the settings as needed.
  1. Click **Save changes**.

- CLI {#cli}

  If you do not have the Yandex Cloud CLI yet, [install and initialize it](../../../cli/quickstart.md#install).

  The folder used by default is the one specified when [creating](../../../cli/operations/profile/profile-create.md) the CLI profile. To change the default folder, use the `yc config set folder-id <folder_ID>` command. You can also specify a different folder for any command using `--folder-name` or `--folder-id`. If you access a resource by its name, the search will be limited to the default folder. If you access a resource by its ID, the search will be global, i.e., through all folders based on access permissions.

  Run this command:

  ```bash
  yc serverless function version create \
    --function-name=<function_name> \
    --runtime <runtime_environment> \
    --entrypoint <entry_point> \
    --memory <RAM_size> \
    --execution-timeout <execution_timeout> \
    --source-path <path_to_ZIP_archive> \
    --service-account-id <service_account_ID> \
    --mount type=object-storage,mount-point=<mount_point>,bucket=<bucket_name>,prefix=<folder_name>,mode=<mount_mode>
  ```

  Where:

  * `--function-name`: Function name.
  * `--runtime`: Function [runtime](../../concepts/runtime/index.md#runtimes).
  * `entrypoint`: Entry point in `<file_name_without_extension>.<handler_name>` format, e.g., `index.handler`.
  * `--memory`: Amount of RAM.
  * `--execution-timeout`: Maximum function execution time before timeout.
  * `--source-path`: Path to the ZIP archive with the function code and required dependencies.
  * `--service-account-id`: Service account [ID](../../../iam/operations/sa/get-id.md). The service account needs the `storage.viewer` [role](../../../storage/security/index.md#storage-viewer) for bucket read access or the `storage.uploader` [role](../../../storage/security/index.md#storage-uploader) for both read and write access.
  * `--mount`: Object Storage [bucket](../../../storage/concepts/bucket.md) mount settings:
      * `type`: Mounted storage type. For a bucket, the value is always `object-storage`.
      * `mount-point`: Mount point. The directory with the mounted bucket will be accessible at `/function/storage/<mount_point>`.
      * `bucket`: [Bucket](../../../storage/concepts/bucket.md#naming) name.
      * `prefix`: Bucket [folder](../../../storage/concepts/object.md#folder) that will be mounted to the function. Skip this field or leave it empty to mount the entire bucket.
      * `mode`: Bucket mount mode, `ro` (read-only) or `rw` (read and write).

      To mount several buckets to a function at the same time, specify `--mount` as many times as you need.

- Terraform {#tf}

  With [Terraform](https://www.terraform.io/), you can quickly create a cloud infrastructure in Yandex Cloud and manage it using configuration files. These files store the infrastructure description written in HashiCorp Configuration Language (HCL). If you change the configuration files, Terraform automatically detects which part of your configuration is already deployed, and what should be added or removed.
  
  Terraform is distributed under the [Business Source License](https://github.com/hashicorp/terraform/blob/main/LICENSE). The [Yandex Cloud provider for Terraform](https://github.com/yandex-cloud/terraform-provider-yandex) is distributed under the [MPL-2.0](https://www.mozilla.org/en-US/MPL/2.0/) license.
  
  For more information about the provider resources, see the guides on the [Terraform](https://www.terraform.io/docs/providers/yandex/index.html) website or [its mirror](../../../terraform/index.md).

  If you do not have Terraform yet, [install it and configure the Yandex Cloud provider](../../../tutorials/infrastructure-management/terraform-quickstart.md#install-terraform).
  
  
  To manage infrastructure using Terraform under a service account or user accounts (a Yandex account, a federated account, or a local user), [authenticate](../../../terraform/authentication.md) using the appropriate method.

  1. Open the Terraform configuration file and add the `mounts` section to the function description:

      ```hcl
      resource "yandex_function" "bucketfunction" {
        ...

        mounts {
          name = "<mount_point>"
          mode = "<mount_mode>"
          object_storage {
            bucket = "<bucket_name>"
            prefix = "<folder_name>"
          }
        }

      }
      ```

      Where:

      * `mounts`: Object Storage [bucket](../../../storage/concepts/bucket.md) mount settings:
          * `name`: Mount point. The directory with the mounted [bucket](../../../storage/concepts/bucket.md) will be accessible at `/function/storage/<mount_point>`.
          * `mode`: Bucket mount mode, `ro` (read-only) or `rw` (read and write).
          * `object_storage`: Bucket settings:
              * `bucket`: [Bucket](../../../storage/concepts/bucket.md#naming) name.
              * `prefix`: Bucket [folder](../../../storage/concepts/object.md#folder) that will be mounted to the container. Leave this field empty to mount the entire bucket.

          To mount several buckets to a function at the same time, specify `mounts` as many times as you need.

      For more on the properties of the `yandex_function` resource, see [this provider guide](../../../terraform/resources/function.md).

  1. Apply the changes:

     1. In the terminal, navigate to the configuration file directory.
     1. Make sure the configuration is correct using this command:
     
        ```bash
        terraform validate
        ```
     
        If the configuration is valid, you will get this message:
     
        ```bash
        Success! The configuration is valid.
        ```
     
     1. Run this command:
     
        ```bash
        terraform plan
        ```
     
        You will see a list of resources and their properties. No changes will be made at this step. Terraform will show any errors in the configuration.
     1. Apply the configuration changes:
     
        ```bash
        terraform apply
        ```
     
     1. Type `yes` and press **Enter** to confirm the changes.

  You can check the function version update and its settings using the [management console](https://console.yandex.cloud) or this [CLI](../../../cli/quickstart.md) command:

  ```bash
  yc serverless function version get <function_version_ID>
  ```

- API {#api}

  Use the [createVersion](../../functions/api-ref/Function/createVersion.md) REST API method for the [Function](../../functions/api-ref/Function/index.md) resource or the [FunctionService/CreateVersion](../../functions/api-ref/grpc/Function/createVersion.md) gRPC API call.

{% endlist %}

## Useful links {#see-also}

* [Mounting external resources to a function file system](../../concepts/mounting.md)
* [Mounting external resources to a container file system](../../../serverless-containers/concepts/mounting.md)