Delete Blobs in Azure Storage

This document explains how to delete blobs, blob snapshots, and blob versions from Azure Blob Storage.

Understanding Deletion Options

Azure Blob Storage offers several ways to manage blob deletion:

• Deleting a blob: This removes the current version of a blob.
• Deleting a blob snapshot: Snapshots are read-only versions of a blob. You can delete them independently.
• Deleting a blob version: If blob versioning is enabled, previous versions of a blob are retained. These can be deleted.
• Deleting a container: This deletes the container and all blobs within it. This is a more drastic operation.

Prerequisites

• An Azure Storage account.
• Permissions to access the storage account and its blobs.

Methods for Deleting Blobs

You can delete blobs using the Azure portal, Azure CLI, Azure PowerShell, or Azure Storage client libraries (SDKs).

1. Using the Azure Portal

The Azure portal provides a user-friendly interface for managing your storage resources.

1. Navigate to your storage account in the Azure portal.
2. Select Containers under Data storage.
3. Select the container that holds the blob you want to delete.
4. Locate the blob in the list.
5. Select the checkbox next to the blob name.
6. Click the Delete button that appears at the top of the container blade.
7. Confirm the deletion in the dialog box.

2. Using Azure CLI

The Azure Command-Line Interface (CLI) is a powerful tool for scripting storage operations.

To delete a blob:

az storage blob delete \
    --account-name <storage-account-name> \
    --container-name <container-name> \
    --name <blob-name> \
    --account-key <storage-account-key>

Replace the placeholders with your actual storage account name, container name, blob name, and account key. You can also use SAS tokens for authentication.

To delete a blob snapshot:

az storage blob delete \
    --account-name <storage-account-name> \
    --container-name <container-name> \
    --name <blob-name> \
    --snapshot <snapshot-time> \
    --account-key <storage-account-key>

To delete all snapshots of a blob:

az storage blob delete \
    --account-name <storage-account-name> \
    --container-name <container-name> \
    --name <blob-name> \
    --delete-snapshots include \
    --account-key <storage-account-key>

3. Using Azure PowerShell

Azure PowerShell provides cmdlets for managing Azure resources.

To delete a blob:

Remove-AzStorageBlob `
    -AccountName <storage-account-name> `
    -Container <container-name> `
    -Blob <blob-name> `
    -Force

To delete all snapshots of a blob:

Remove-AzStorageBlob `
    -AccountName <storage-account-name> `
    -Container <container-name> `
    -Blob <blob-name> `
    -IncludeSnapshots `
    -Force

4. Using Azure Storage Client Libraries (SDKs)

You can programmatically delete blobs using the Azure Storage SDKs available for various programming languages.

Example using .NET:

using Azure.Storage.Blobs;

// Replace with your actual connection string
string connectionString = "YOUR_AZURE_STORAGE_CONNECTION_STRING";
string containerName = "mycontainer";
string blobName = "myblob.txt";

BlobServiceClient blobServiceClient = new BlobServiceClient(connectionString);
BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(containerName);
BlobClient blobClient = containerClient.GetBlobClient(blobName);

try
{
    Response response = await blobClient.DeleteAsync();
    if (response.Value)
    {
        Console.WriteLine($"Blob '{blobName}' deleted successfully.");
    }
    else
    {
        Console.WriteLine($"Failed to delete blob '{blobName}'.");
    }
}
catch (RequestFailedException e)
{
    Console.WriteLine($"Error deleting blob: {e.Message}");
}

Configuring Deletion Protection and Soft Delete

To protect against accidental deletion, you can configure:

• Immutable Storage: Prevents any modifications or deletions for a specified period.
• Soft Delete for Blobs: Retains deleted blobs for a configured retention period, allowing for recovery.
• Blob Versioning: Automatically creates a new version of a blob when it's modified or deleted, enabling access to previous states.

These features can be configured at the storage account level and provide a critical safety net for your data.

Enabling Soft Delete

Soft delete can be enabled for blobs, blob snapshots, and blob versions. You can configure the retention period from 1 to 365 days.

Enabling Blob Versioning

When versioning is enabled, every overwrite or delete operation on a blob creates a new version. You can then restore previous versions.

Troubleshooting Deletion Issues

• Permissions: Ensure the account or user has the necessary read, write, and delete permissions.
• Lease: Blobs under an active lease cannot be deleted. Break the lease first if necessary.
• Container Deletion: A container cannot be deleted if it contains active leases on any of its blobs.
• Versioning/Soft Delete: If a blob is not truly gone, check if soft delete or versioning is enabled and if you're looking at the correct state of the blob.

Further Reading

• Configure immutable storage for blobs
• Enable soft delete for blobs
• Enable blob versioning