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Azure Storage Blobs client library for .NET

Server Version: 2021-02-12, 2020-12-06, 2020-10-02, 2020-08-04, 2020-06-12, 2020-04-08, 2020-02-10, 2019-12-12, 2019-07-07, and 2019-02-02

Azure Blob storage is Microsoft's object storage solution for the cloud. Blob storage is optimized for storing massive amounts of unstructured data. Unstructured data is data that does not adhere to a particular data model or definition, such as text or binary data.

Source code | Package (NuGet) | API reference documentation | REST API documentation | Product documentation

Getting started

Install the package

Install the Azure Storage Blobs client library for .NET with NuGet:

dotnet add package Azure.Storage.Blobs

Prerequisites

You need an Azure subscription and a Storage Account to use this package.

To create a new Storage Account, you can use the Azure Portal, Azure PowerShell, or the Azure CLI. Here's an example using the Azure CLI:

az storage account create --name MyStorageAccount --resource-group MyResourceGroup --location westus --sku Standard_LRS

Authenticate the client

In order to interact with the Azure Blobs Storage service, you'll need to create an instance of the BlobServiceClient class. The Azure Identity library makes it easy to add Azure Active Directory support for authenticating Azure SDK clients with their corresponding Azure services.

// Create a BlobServiceClient that will authenticate through Active Directory
Uri accountUri = new Uri("https://MYSTORAGEACCOUNT.blob.core.windows.net/");
BlobServiceClient client = new BlobServiceClient(accountUri, new DefaultAzureCredential());

Learn more about enabling Azure Active Directory for authentication with Azure Storage in our documentation and our samples.

Key concepts

Blob storage is designed for:

  • Serving images or documents directly to a browser.
  • Storing files for distributed access.
  • Streaming video and audio.
  • Writing to log files.
  • Storing data for backup and restore, disaster recovery, and archiving.
  • Storing data for analysis by an on-premises or Azure-hosted service.

Blob storage offers three types of resources:

  • The storage account used via BlobServiceClient
  • A container in the storage account used via BlobContainerClient
  • A blob in a container used via BlobClient

Learn more about options for authentication (including Connection Strings, Shared Key, Shared Key Signatures, Active Directory, and anonymous public access) in our samples.

Thread safety

We guarantee that all client instance methods are thread-safe and independent of each other (guideline). This ensures that the recommendation of reusing client instances is always safe, even across threads.

Additional concepts

Client options | Accessing the response | Long-running operations | Handling failures | Diagnostics | Mocking | Client lifetime

Examples

Uploading a blob

// Get a connection string to our Azure Storage account.  You can
// obtain your connection string from the Azure Portal (click
// Access Keys under Settings in the Portal Storage account blade)
// or using the Azure CLI with:
//
//     az storage account show-connection-string --name <account_name> --resource-group <resource_group>
//
// And you can provide the connection string to your application
// using an environment variable.

string connectionString = "<connection_string>";
string containerName = "sample-container";
string blobName = "sample-blob";
string filePath = "sample-file";

// Get a reference to a container named "sample-container" and then create it
BlobContainerClient container = new BlobContainerClient(connectionString, containerName);
container.Create();

// Get a reference to a blob named "sample-file" in a container named "sample-container"
BlobClient blob = container.GetBlobClient(blobName);

// Upload local file
blob.Upload(filePath);

Downloading a blob

// Get a temporary path on disk where we can download the file
string downloadPath = "hello.jpg";

// Download the public MacBeth copy at https://www.gutenberg.org/cache/epub/1533/pg1533.txt
new BlobClient(new Uri("https://www.gutenberg.org/cache/epub/1533/pg1533.txt")).DownloadTo(downloadPath);

Enumerating blobs

// Get a connection string to our Azure Storage account.
string connectionString = "<connection_string>";
string containerName = "sample-container";
string filePath = "hello.jpg";

// Get a reference to a container named "sample-container" and then create it
BlobContainerClient container = new BlobContainerClient(connectionString, containerName);
container.Create();

// Upload a few blobs so we have something to list
container.UploadBlob("first", File.OpenRead(filePath));
container.UploadBlob("second", File.OpenRead(filePath));
container.UploadBlob("third", File.OpenRead(filePath));

// Print out all the blob names
foreach (BlobItem blob in container.GetBlobs())
{
    Console.WriteLine(blob.Name);
}

Async APIs

We fully support both synchronous and asynchronous APIs.

// Get a temporary path on disk where we can download the file
string downloadPath = "hello.jpg";

// Download the public MacBeth copy at https://www.gutenberg.org/cache/epub/1533/pg1533.txt
await new BlobClient(new Uri("https://www.gutenberg.org/cache/epub/1533/pg1533.txt")).DownloadToAsync(downloadPath);

Troubleshooting

All Blob service operations will throw a RequestFailedException on failure with helpful ErrorCodes. Many of these errors are recoverable.

// Get a connection string to our Azure Storage account.
string connectionString = "<connection_string>";
string containerName = "sample-container";

// Try to delete a container named "sample-container" and avoid any potential race conditions
// that might arise by checking if the container is already deleted or is in the process
// of being deleted.
BlobContainerClient container = new BlobContainerClient(connectionString, containerName);

try
{
    container.Delete();
}
catch (RequestFailedException ex)
    when (ex.ErrorCode == BlobErrorCode.ContainerBeingDeleted ||
          ex.ErrorCode == BlobErrorCode.ContainerNotFound)
{
    // Ignore any errors if the container being deleted or if it has already been deleted
}

Next steps

Get started with our Blob samples:

  1. Hello World: Upload, download, and list blobs (or asynchronously)
  2. Auth: Authenticate with connection strings, public access, shared keys, shared access signatures, and Azure Active Directory.

Contributing

See the Storage CONTRIBUTING.md for details on building, testing, and contributing to this library.

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit cla.microsoft.com.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.

Impressions