Azure Storage Blobs client library for .NET

Server Version: 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 --version 12.0.0-preview.4

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

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.

Examples

Uploading a blob

using Azure.Storage;
using Azure.Storage.Blobs;
using Azure.Storage.Blobs.Models;

// 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>";

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

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

// Open a file and upload it's data
using (FileStream file = File.OpenRead("local-file.jpg"))
{
    blob.Upload(file);
}

Downloading a blob

// Get a reference to the public blob at https://aka.ms/bloburl
BlobClient blob = new BlobClient(new Uri("https://aka.ms/bloburl"));

// Download the blob
Response<BlobDownloadInfo> download = blob.Download();
using (FileStream file = File.OpenWrite("hello.jpg"))
{
    download.Value.Content.CopyTo(file);
}

Enumerating blobs

string connectionString = "<connection_string>";

// Get a reference to a container named "sample-container"
BlobContainerClient container = new BlobContainerClient(connectionString, "sample-container");

// List all of its blobs
foreach (BlobItem blob in container.GetBlobs())
{
    Console.WriteLine(blob.Name);
}

Async APIs

We fully support both synchronous and asynchronous APIs.

// Get a reference to the public blob at https://aka.ms/bloburl
BlobClient blob = new BlobClient(new Uri("https://aka.ms/bloburl"));

// Download the blob
Response<BlobDownloadInfo> download = await blob.DownloadAsync();
using (FileStream file = File.OpenWrite("hello.jpg"))
{
    await download.Value.Content.CopyToAsync(file);
}

Authenticating with Azure.Identity

The Azure Identity library provides easy Azure Active Directory support for authentication.

using Azure.Identity;

// 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.

Troubleshooting

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

string connectionString = "<connection_string>";

// Try to create a container named "sample-container" and avoid any potential race
// conditions that might arise by checking if the container exists before creating
BlobContainerClient container = new BlobContainerClient(connectionString, "sample-container");
try
{
    container.Create();
}
catch (RequestFailedException ex)
    when (ex.ErrorCode == BlobErrorCode.ContainerAlreadyExists)
{
    // Ignore any errors if the container already exists
}

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 opencode@microsoft.com with any additional questions or comments.

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