Undelete Blob

Article
04/11/2023

The Undelete Blob operation restores the contents and metadata of a soft-deleted blob, and any associated soft-deleted snapshots.

Undelete Blob is supported only on version 2017-07-29 or later.

Request

You can construct the Undelete Blob request as follows. HTTPS is recommended. Replace myaccount with the name of your storage account.

PUT method request URI	HTTP version
`https://myaccount.blob.core.windows.net/mycontainer/myblob?comp=undelete`	HTTP/1.1

Emulated storage service URI

When you make a request against the emulated storage service, specify the emulator hostname and Azure Blob Storage port as 127.0.0.1:10000, followed by the emulated storage account name.

PUT method request URI	HTTP version
`http://127.0.0.1:10000/ devstoreaccount1/mycontainer/myblob?comp=undelete`	HTTP/1.1

For more information, see Use Azurite emulator for local Azure Storage development.

URI parameters

You can specify the following additional parameter on the request URI.

Parameter	Description
`timeout`	Optional. The `timeout` parameter is expressed in seconds. For more information, see Setting timeouts for Blob Storage operations.

Request headers (all blob types)

The following table describes required and optional request headers for all blob types.

Request header	Description
`Authorization`	Required. Specifies the authorization scheme, account name, and signature. For more information, see Authorize requests to Azure Storage.
`Date` or `x-ms-date`	Required. Specifies the Coordinated Universal Time (UTC) for the request. For more information, see Authorize requests to Azure Storage.
`x-ms-version`	Required for all authorized requests. Specifies the version of the operation to use for this request. For more information, see Versioning for the Azure Storage services.
`x-ms-undelete-source`	Optional. Version 2020-08-04 and later. Only for accounts enabled with hierarchical namespace. The path of the soft-deleted blob to undelete. The format is `blobPath?deletionid=<id>`. The account and container name aren't included in the path. `DeletionId` is the unique identifier of the soft-deleted blob. You can retrieve it by listing soft-deleted blobs with the `List Blobs` REST API for accounts enable with hierarchical namespace. The path should be percent encoded.
`x-ms-client-request-id`	Optional. Provides a client-generated, opaque value with a 1-kibibyte (KiB) character limit that's recorded in the logs when logging is configured. We highly recommend that you use this header to correlate client-side activities with requests that the server receives. For more information, see Monitor Azure Blob Storage.

Request body

None.

Response

The response includes an HTTP status code and a set of response headers.

Status code

A successful operation returns status code 200 (OK). For information about status codes, see Status and error codes.

Response headers

The response for this operation includes the following headers. The response can also include additional, standard HTTP headers. All standard headers conform to the HTTP/1.1 protocol specification.

Syntax	Description
`x-ms-request-id`	This header uniquely identifies the request that was made, and can be used for troubleshooting the request. For more information, see Troubleshooting API operations.
`x-ms-version`	Indicates the version of Blob Storage used to run the request.
`Date`	A UTC date/time value that indicates the time at which the response was initiated. The service generates this value.
`x-ms-client-request-id`	You can use this header to troubleshoot requests and corresponding responses. The value of this header is equal to the value of the `x-ms-client-request-id` header, if it's present in the request. The value is at most 1,024 visible ASCII characters. If the `x-ms-client-request-id` header isn't present in the request, this header won't be present in the response.

Response body

None.

Authorization

Authorization is required when calling any data access operation in Azure Storage. You can authorize the Undelete Blob operation as described below.

Azure Storage supports using Azure Active Directory (Azure AD) to authorize requests to blob data. With Azure AD, you can use Azure role-based access control (Azure RBAC) to grant permissions to a security principal. The security principal may be a user, group, application service principal, or Azure managed identity. The security principal is authenticated by Azure AD to return an OAuth 2.0 token. The token can then be used to authorize a request against the Blob service.

To learn more about authorization using Azure AD, see Authorize access to blobs using Azure Active Directory.

Permissions

Listed below are the RBAC action necessary for an Azure AD user, group, or service principal to call the Undelete Blob operation, and the least privileged built-in Azure RBAC role that includes this action:

Azure RBAC action: Microsoft.Storage/storageAccounts/blobServices/containers/write
Least privileged built-in role: Storage Blob Data Contributor

To learn more about assigning roles using Azure RBAC, see Assign an Azure role for access to blob data.

A shared access signature (SAS) provides secure delegated access to resources in a storage account. With a SAS, you have granular control over how a client can access data. You can specify what resource the client may access, what permissions they have to those resources, and how long the SAS is valid.

The Undelete Blob operation supports three types of shared access signatures: user delegation SAS, service SAS, and account SAS.

As a security best practice, we recommend that you use Azure AD credentials rather than the storage account key, which can be more easily compromised. If your application design requires shared access signatures, use Azure AD credentials to create a user delegation SAS, when possible.

When Shared Key access is disallowed for the storage account, a service SAS token or an account SAS token will not be permitted on a request to Blob Storage. To learn more, see Understand how disallowing Shared Key affects SAS tokens.

User delegation SAS

A user delegation SAS is secured with Azure Active Directory (Azure AD) credentials and also by the permissions specified for the SAS.

Calling the Undelete Blob operation using a SAS token delegated to a container resource requires the Write (w) permission as part of the user delegation SAS token.

To learn more about the user delegation SAS, see Create a user delegation SAS.

Service SAS

A service SAS is secured with the storage account key. A service SAS delegates access to a resource in a single Azure Storage service, such as blob storage.

Calling the Undelete Blob operation using a SAS token delegated to a container resource requires the Write (w) permission as part of the service SAS token.

To learn more about the service SAS, see Create a service SAS.

Account SAS

An account SAS is secured with the storage account key. An account SAS delegates access to resources in one or more of the storage services. All of the operations available via a service or user delegation SAS are also available via an account SAS.

The following table indicates the signed resource type and signed permissions to specify when delegating access:

Operation	Signed service	Signed resource type	Signed permission
Undelete Blob	Blob (b)	Container (c)	Write (w)

To learn more about the account SAS, see Create an account SAS.

Remarks

When you undelete a soft-deleted blob, the blob and any associated snapshots are available for operations by using other APIs. When you undelete a blob that isn't soft-deleted or has no soft-deleted snapshots, the operation succeeds without any changes.