Bulk download from Azure Blob Storage with C#

To bulk download files from Azure Blob Storage using C#, you can use the Azure.Storage.Blobs SDK. Below is a step-by-step guide:

1. Install the required NuGet package

Install Azure.Storage.Blobs using NuGet Package Manager:

Install-Package Azure.Storage.Blobs

2. Set up connection details

Azure Storage Account connection string
Blob container name
Local folder path for saving the downloaded files

3. List and Download Blobs in Bulk

Use BlobContainerClient to get the list of blobs.

Download each blob asynchronously using DownloadToAsync

using System;
using System.IO;
using System.Threading.Tasks;
using Azure.Storage.Blobs;
using Azure.Storage.Blobs.Models;

class Program
{
    private const string connectionString = "Your_Azure_Storage_Connection_String";
    private const string containerName = "your-container-name";
    private const string downloadFolderPath = @"C:\DownloadedBlobs"; // Local save path

    static async Task Main()
    {
        await BulkDownloadBlobsAsync();
    }

    private static async Task BulkDownloadBlobsAsync()
    {
        try
        {
            BlobContainerClient containerClient = new BlobContainerClient(connectionString, containerName);

            await foreach (BlobItem blobItem in containerClient.GetBlobsAsync())
            {
                string blobName = blobItem.Name;
                string localFilePath = Path.Combine(downloadFolderPath, blobName);

                // Create directories if they don't exist
                Directory.CreateDirectory(Path.GetDirectoryName(localFilePath));

                Console.WriteLine($"Downloading: {blobName}");

                BlobClient blobClient = containerClient.GetBlobClient(blobName);
                await blobClient.DownloadToAsync(localFilePath);
            }

            Console.WriteLine("Bulk download completed.");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }
}

Explanation

Initialize BlobContainerClient using the storage account connection string.
List all blobs in the container using GetBlobsAsync().
Iterate over the blobs and download each file asynchronously.
Ensure directory structure exists before saving files locally.
Handle exceptions gracefully.

Optimizing for Large Blob Containers

If your container has thousands of blobs, consider:

Parallel downloads using Task.WhenAll().
Filtering blobs by prefix (e.g., download only specific folders).
Resuming downloads by checking if the file already exists.