Store and retrieve files from Azure blob storage
ASP.NET Core web applications often need to store files on the server. One of
the approaches to storing files on the server side is to store them into Azure
blob storage. For example, you can store documents, audio files, video files,
and images into Azure blob storage. This article shows you how to add, download,
and remove files from Azure blob storage.
In order to work with this example you need to create an Azure storage
account. You can do that by signing in to the Azure portal and clicking the
Storage account option at the top.
Then complete the form that follows and create the account.
The storage account creation might take some time. Once you get the success
notification, go to the storage account you just created and click on the Access
Then copy the values under key1 section (key and connection string) and keep
them at a handy location. You will need them in your .NET Core application.
For the sake of simplicity I am going to use a console application (.NET
Core) to demonstrate the use of Azure blob storage but you can use any other
kind of projects also.
Once the project is created add NuGet package for
Then write the following code to upload an image file from your local folder
to Azure blob storage.
static void Main(string args)
string connStr = "your_connection_string_here";
CloudStorageAccount account = CloudStorageAccount.Parse(connStr);
CloudBlobClient client = account.CreateCloudBlobClient();
CloudBlobContainer container = client.
CloudBlockBlob blob = container.
As you can see the code stores the Azure storage account's connection string
in a string variable. You should replace it with your own connection string.
The code then creates an object of CloudStorageAccount class. The
CloudStorageAccount class represents an Azure storage account and you supply the
connection string to it while creating the object.
Then an object of CloudBlobClient class is created. The CloudBlobClient class
allows you to store and retrieve blob data to your account.
The code then uses the GetContainerReference() method to get a
reference of a blob container (CloudBlobContainer object). At this stage no such
container exists and hence the code also calls the CreateIfNotExists() method of
the CloudBlobContainer class.
It then creates a CloudBlockBlob object by specifying the name of the blob.
If this name doesn't exist it will be created and its reference is returned
otherwise an existing reference is returned.
Finally, the code calls the UploadFromFile() method of CloudBlockBlob class
to upload a file from local path to the blob.
The following figure shows the myblob entry getting created in the Azure
Clicking on the myblobcontainer will take you to its content and myblob entry
will be visible.
How would you download the content of myblob into a file? That's easy. Most
of the code remains the same except the last line. Instead of UploadFromFile()
you would use:
The DownloadToFile() accepts a file name where the blob content is to be
If you wish to delete a blob entry, you can do so using Delete() or
DeleteIfExist() methods of CloudBlockBlob class.
That's it for now! Keep coding!!