Mounting a bucket to a function

Written by

Updated at May 5, 2025

You can mount Yandex Object Storage buckets to a function. Mounting a bucket automatically creates a new function version.

To mount buckets to a function:

Management console

CLI

Terraform

API

In the management console, select the folder containing the function.
From the list of services, select Cloud Functions.
Select a function.
Navigate to the Editor tab.
In the Parameters section, select or create a new service account with one of these roles:
- storage.viewer to only read data from the mounted bucket.
- storage.uploader to read and write data from/to the mounted bucket.
Expand Additional settings.
Under Mounted buckets:
1. Click Add bucket.
2. Specify the following in the field:
  - Mount point: Name of the mount point. Use this path to access the directory the bucket will be mounted to: /function/storage/<mount_point>.
  - Bucket: Bucket you want to mount. If necessary, create a new bucket.
  - Directory: Bucket directory that will be mounted to the container. Leave this field empty to mount the entire bucket.
3. Enable Read-only to disable writing to the bucket. With this option on, data from the mounted bucket will be read-only.
To mount an additional bucket to the function, click Add bucket again and configure the parameters as needed.
Click Save changes.

If you do not have the Yandex Cloud CLI yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

Run this command:

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=<directory_name>,mode=<mount_mode>

Where:

--function-name: Function name.
--runtime: Function runtime environment.
--entrypoint: Entry point in the following format: <file_name_without_extension>.<listener_name>, e.g., index.handler.
--memory: Amount of RAM.
--execution-timeout: Maximum running time of the function until timeout.
--source-path: Path to the ZIP archive containing the function code and relevant dependencies.
--service-account-id: Service account ID. The service account needs the storage.viewer role to read from the bucket or the storage.uploader role to both read and write.
--mount: Object Storage bucket mounting parameters:
- type: Mounted storage type. For a bucket, the value is always object-storage.
- mount-point: Mount point. Use this path to access the directory the bucket will be mounted to: /function/storage/<mount_point>.
- bucket: Bucket name.
- prefix: Bucket directory 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, set the --mount parameter as many times as you need.

With Terraform, 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. The Yandex Cloud provider for Terraform is distributed under the MPL-2.0 license.

For more information about the provider resources, see the documentation on the Terraform website or mirror website.

If you do not have Terraform yet, install it and configure its Yandex Cloud provider.

Open the Terraform configuration file and add the mounts section to the function description:
```
resource "yandex_function" "bucketfunction" {
  ...

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

}
```
Where:
- mounts: Object Storage bucket mounting parameters:
  - name: Mount point. Use this path to access the directory the bucket will be mounted to: /function/storage/<mount_point>.
  - mode: Bucket mount mode, ro (read-only) or rw (read and write).
  - object_storage: Bucket parameters:
    - bucket: Bucket name.
    - prefix: Bucket 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, set the mounts section as many times as you need.
For more information about the yandex_function resource parameters, see this Terraform article.
Apply the changes:
1. In the terminal, change to the folder where you edited the configuration file.
2. Make sure the configuration file is correct using the command:
```
terraform validate
```
  If the configuration is correct, the following message is returned:
```
Success! The configuration is valid.
```
3. Run the command:
```
terraform plan
```
  The terminal will display a list of resources with parameters. No changes are made at this step. If the configuration contains errors, Terraform will point them out.
4. Apply the configuration changes:
```
terraform apply
```
5. Confirm the changes: type yes in the terminal and press Enter.

You can check the function version update and its settings using the management console or this CLI command:

yc serverless function version get <function_version_ID>

Use the createVersion REST API method for the Function resource or the FunctionService/CreateVersion gRPC API call.

Mounting a bucket to a function

See also

Was the article helpful?

Mounting a bucket to a function

See alsoSee also

Was the article helpful?

See also