How to Create Azure Blob Storage Resources by using .NET Client Library?

• Data folder - create data1 folder to upload and download data into it.

mkdir data1

3.2. Starter code

Add following starter code into the application.

• Application editing - open Program.cs file to edit it in the Cloud Shell.

code Program.cs

• Replace code - replace existing code with the following code.

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

Console.WriteLine("Azure Blob Storage\n");

// configure the DefaultAzureCredential using DefaultAzureCredentialOptions object
DefaultAzureCredentialOptions options = new()
{
    ExcludeEnvironmentCredential = true,
    ExcludeManagedIdentityCredential = true
};

// Run asynchronously and wait for results before proceeding
await ProcessAsync();

Console.WriteLine("\nPress any key to exit the application!");
Console.ReadLine();

async Task ProcessAsync()
{
    // CREATE - BLOB STORAGE CLIENT

    // CREATE - CONTAINER

    // CREATE - LOCAL FILE FOR UPLOAD TO BLOB STORAGE

    // UPLOAD - FILE TO BLOB STORAGE

    // LIST - BLOBS IN THE CONTAINER

    // DOWNLOAD - BLOB TO LOCAL FILE
}

• Save & close - Press Ctrl + S to save changes and continue.

3.3. Complete code

Add following code to complete the application. Now let’s update the code fore commented lines for specific operations one by one with description.

3.3.1. Create a blob storage client

BlobServiceClient is a primary entry point to manage containers and blobs in a storage account. Client uses DefaultAzureCredential for authentication.

Locate // CREATE - BLOB STORAGE CLIENT comment, then add following code directly beneath comment.

// CREATE - BLOB STORAGE CLIENT

// Create credential using DefaultAzureCredential
string accountName = "YOUR_ACCOUNT_NAME"; // Replace with your storage account name

// Use DefaultAzureCredential with options configured at top of program
DefaultAzureCredential credential = new DefaultAzureCredential(options);

// Create BlobServiceClient using endpoint and DefaultAzureCredential
string blobServiceEndpoint = $"https://{accountName}.blob.core.windows.net";

BlobServiceClient blobServiceClient = new BlobServiceClient(new Uri(blobServiceEndpoint), credential);

3.3.2. Create a container

Create a container if it’s not exists.

Locate // CREATE - CONTAINER comment, then add following code directly beneath comment.

// CREATE - CONTAINER

// Container's unique name
string containerName = "textFiles";

// Create container and return container client object
Console.WriteLine("Create container : " + containerName);
//BlobContainerClient containerClient = await blobServiceClient.CreateBlobContainerAsync(containerName);

// Get BlobContainerClient for container name
BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(containerName);

// Create container if it does not exist
// Method returns null if container already exists
var response = await containerClient.CreateIfNotExistsAsync(PublicAccessType.None);

// null if container already exists
if (response != null)
{
    Console.WriteLine("Container created successfully, press any key to continue!");
    Console.ReadLine();
}
else
{
    Console.WriteLine("Container already exists, No action taken, press any key to exiting program!");
    Console.ReadLine();
    return;
}

3.3.3. Create a local file for upload to blob storage

Let’s create a file in to data1 directory and later on it will be uploaded to the container.

Locate // CREATE - LOCAL FILE FOR UPLOAD TO BLOB STORAGE comment, then add following code directly beneath comment.

// CREATE - LOCAL FILE FOR UPLOAD TO BLOB STORAGE

// Create local file in ./data1/ directory for uploading and downloading
Console.WriteLine("Create local file for upload to Blob storage!");
string localPath = "./data1/";
string fileName = "FN" + Guid.NewGuid().ToString() + ".txt";
string localFilePath = Path.Combine(localPath, fileName);

// Write text in to file
await File.WriteAllTextAsync(localFilePath, "Hi, this is sample text!");
Console.WriteLine("Local file created successfully, press any key to continue!");
Console.ReadLine();

3.3.4. Upload a file to blob storage

GetBlobClient method gets a reference to a BlobClient object by container created previously. UploadAsync method. uploads a generated local file. It creates blob if it doesn't already exist else overwrites it.

Locate // UPLOAD - FILE TO BLOB STORAGE comment, then add following code directly beneath comment.

// UPLOAD - FILE TO BLOB STORAGE

// Get reference to blob and upload file
BlobClient blobClient = containerClient.GetBlobClient(fileName);

Console.WriteLine("Upload to Blob storage as blob :\n\t {0}", blobClient.Uri);

// Open file and upload it's data
using (FileStream uploadFileStream = File.OpenRead(localFilePath))
{
    await blobClient.UploadAsync(uploadFileStream);
    uploadFileStream.Close();
}

// Verify file uploaded successfully
bool blobExists = await blobClient.ExistsAsync();
if (blobExists)
{
    Console.WriteLine("File uploaded successfully, press any key to continue!");
    Console.ReadLine();
}
else
{
    Console.WriteLine("File upload failed, press any key to exiting program!");
    Console.ReadLine();
    return;
}

3.3.5. List all blobs in the container

GetBlobsAsync method list out all blobs in to the container.

Locate // LIST - BLOBS IN THE CONTAINER comment, then add following code directly beneath comment.

// LIST - BLOBS IN THE CONTAINER

Console.WriteLine("List of blobs in container");
await foreach (BlobItem blobItem in containerClient.GetBlobsAsync())
{
    Console.WriteLine("\t" + blobItem.Name);
}

Console.WriteLine("Press any key to continue!");
Console.ReadLine();

3.3.6. Download a blob to local file

DownloadStreamingAsync or DownloadAsync method downloads a blob created previously in to local file system. A suffix "downloadedFile" is added to differentiate the downloaded file in local file system.

Locate // DOWNLOAD - BLOB TO LOCAL FILE comment, then add following code directly beneath comment.

// DOWNLOAD - BLOB TO LOCAL FILE

// Adds the string "DOWNLOADED" before the .txt extension so it doesn't 
// overwrite the original file

string downloadFilePath = localFilePath.Replace(".txt", "downloadedFile.txt");

Console.WriteLine("Downloading blob at : {0}", downloadFilePath);

// Download the blob's contents and save it to a file
BlobDownloadInfo download = await blobClient.DownloadStreamingAsync();// DownloadAsync();

using (FileStream downloadFileStream = File.OpenWrite(downloadFilePath))
{
    await download.Content.CopyToAsync(downloadFileStream);
}

Console.WriteLine("Blob downloaded successfully at : {0}", downloadFilePath);

Now it’s time to save and close the file by pressing Ctrl + s to save file and then Ctrl + q to exit the editor. Here, by with this article a complete code is attached in Program.cs file.

4. Sign in to Azure and Run application

Now one by one execute the following commands in Cloud Shell to run an application and perform the mentioned steps to verify the result outcomes.

• Sign in using “az login” command. Sign into Azure is mandatory even though cloud shell session already authenticated.

az login

• Run application using “dotnet run” command will start console application. Different output messages will be displayed in console as written in the code.

dotnet run

• View files - go to data1 directory to view the uploaded and downloaded file

cd data1
ls

• Check Azure portal - one can view the created container, uploaded blob storage file, etc. from Azure portal using below steps:

  • Open Azure portal and navigate to Azure Storage account which is created.

  • Expand to “Data storage” in left navigation panel and select the Containers.

  • Select a container created through application and view a uploaded blob.

5. Clean up resources

Once finished the exercise it’s recommended to delete cloud resources are being created to avoid the unnecessary resource usage and any future costs. Deleting a resource group will delete all resources contained within it.

• In Visual Studio Code, select the Azure icon to open the Azure explorer.

• In the Resource Groups section, select resource group which are created in this exercise to deleted them.

• Right-click to selected resource group and select Delete.

6. Summary

Here, first a complete process is described in detailed to create Azure Storage account and build .NET console application by using Azure Storage Blob client library. After that create a container, upload a file to created blob storage, list out the blobs, and download a file. At the end resources are being cleaned up. With this article a complete code is attached in Program.cs file.