Upload And Download File To Azure Blob Storage Using C#

public static class AzureOperations
{
    #region ConfigParams
    public static string tenantId;
    public static string applicationId;
    public static string clientSecret;
    #endregion

    public static void UploadFile(AzureOperationHelper azureOperationHelper)
    {
        CloudBlobContainer blobContainer = CreateCloudBlobContainer(
            tenantId,
            applicationId,
            clientSecret,
            azureOperationHelper.storageAccountName,
            azureOperationHelper.containerName,
            azureOperationHelper.storageEndPoint
        );

        blobContainer.CreateIfNotExists();
        CloudBlockBlob blob = blobContainer.GetBlockBlobReference(azureOperationHelper.blobName);
        blob.UploadFromFile(azureOperationHelper.srcPath);
    }

    public static void DownloadFile(AzureOperationHelper azureOperationHelper)
    {
        CloudBlobContainer blobContainer = CreateCloudBlobContainer(
            tenantId,
            applicationId,
            clientSecret,
            azureOperationHelper.storageAccountName,
            azureOperationHelper.containerName,
            azureOperationHelper.storageEndPoint
        );

        CloudBlockBlob blob = blobContainer.GetBlockBlobReference(azureOperationHelper.blobName);
        blob.DownloadToFile(azureOperationHelper.destinationPath, FileMode.OpenOrCreate);
    }

    private static CloudBlobContainer CreateCloudBlobContainer(
        string tenantId,
        string applicationId,
        string clientSecret,
        string storageAccountName,
        string containerName,
        string storageEndPoint
    )
    {
        string accessToken = GetUserOAuthToken(tenantId, applicationId, clientSecret);
        TokenCredential tokenCredential = new TokenCredential(accessToken);
        StorageCredentials storageCredentials = new StorageCredentials(tokenCredential);
        CloudStorageAccount cloudStorageAccount = new CloudStorageAccount(
            storageCredentials,
            storageAccountName,
            storageEndPoint,
            useHttps: true
        );

        CloudBlobClient blobClient = cloudStorageAccount.CreateCloudBlobClient();
        CloudBlobContainer blobContainer = blobClient.GetContainerReference(containerName);
        return blobContainer;
    }

    static string GetUserOAuthToken(string tenantId, string applicationId, string clientSecret)
    {
        const string ResourceId = "https://storage.azure.com/";
        const string AuthInstance = "https://login.microsoftonline.com/{0}/";
        string authority = string.Format(CultureInfo.InvariantCulture, AuthInstance, tenantId);
        AuthenticationContext authContext = new AuthenticationContext(authority);
        var clientCred = new ClientCredential(applicationId, clientSecret);
        AuthenticationResult result = authContext.AcquireTokenAsync(ResourceId, clientCred).Result;
        return result.AccessToken;
    }
}

Test it in a Console application.

class Program
{
    static void Main(string[] args)
    {
        // Set Ids of your Azure account
        AzureOperations.applicationId = "";
        AzureOperations.clientSecret = "";
        AzureOperations.tenantId = "";

        // Demo Upload File
        string srcPathToUpload = @"C:\Users\abdul.rehman\Desktop\AzureFileUpload\myfile.txt";
        UploadFile(srcPathToUpload);

        // Demo Download File
        string azurePathInBlob = "dev/files/myfile.txt";
        string destinationPath = @"C:\Users\abdul.rehman\Desktop\AzureFileDownload\myfile.txt";
        DownloadFile(destinationPath, azurePathInBlob);
    }

    public static void UploadFile(string srcPath)
    {
        AzureOperationHelper azureOperationHelper = new AzureOperationHelper();
        // your Storage Account Name
        azureOperationHelper.storageAccountName = "dbpoc";
        azureOperationHelper.storageEndPoint = "core.windows.net";
        // File path to upload
        azureOperationHelper.srcPath = srcPath;
        // Your Container Name
        azureOperationHelper.containerName = "filecontainer";
        // Destination Path you can set it file name or if you want to put it in folders do it like below
        azureOperationHelper.blobName = $"dev/files/{Path.GetFileName(srcPath)}";
        AzureOperations.UploadFile(azureOperationHelper);
    }

    public static void DownloadFile(string destinationPath, string srcPath)
    {
        AzureOperationHelper azureOperationHelper = new AzureOperationHelper();
        // your Storage Account Name
        azureOperationHelper.storageAccountName = "dbpoc";
        azureOperationHelper.storageEndPoint = "core.windows.net";
        // Destination Path where you want to download file
        azureOperationHelper.destinationPath = destinationPath;
        // Your Container Name
        azureOperationHelper.containerName = "filecontainer";
        // Blob Path in container where to download File
        azureOperationHelper.blobName = srcPath;

        AzureOperations.DownloadFile(azureOperationHelper);
    }
}

NuGet Dependencies

1. WindowsAzure.Storage (I have installed v9.3.3).
2. Microsoft.IdentityModel.Clients.ActiveDirectory (I have installed v4.4.2).

There are a few things you need to check.

1. The container name should be in lowercase. I don't know why it is not handled but in this version, it is not working with uppercase.
2. Permissions are very critical. Your application role must have read/write/delete permissions on Blob Management and Data as well.

Summary

In this above sample, we learned how to manage our files on Azure Blob Storage with Active Directory Authentication using the application Secret Key. And like the Native app, no popup will be shown to enter the credentials in order to get the access token.

I have also uploaded the sample console application that you can download and test with your Azure credentials. Feel free to contact me in case of an issue.

Download Complete Sample

References

• https://docs.microsoft.com/en-us/azure/storage/blobs/storage-upload-process-images?tabs=dotnet
• https://docs.microsoft.com/en-us/azure/storage/blobs/storage-quickstart-blobs-dotnet?tabs=windows