Tutorial: Upload image data in the cloud with Azure Storage

This tutorial is part one of a series. In this tutorial, you will learn how to deploy a web app that uses the Azure Storage Client Library to upload images to a storage account. When you're finished, you'll have a web app that stores and displays images from Azure storage.

In part one of the series, you learn how to:

  • Create a storage account
  • Create a container and set permissions
  • Retrieve an access key
  • Deploy a web app to Azure
  • Configure app settings
  • Interact with the web app


To complete this tutorial, you need an Azure subscription. Create a free account before you begin.

Use Azure Cloud Shell

Azure hosts Azure Cloud Shell, an interactive shell environment that you can use through your browser. You can use either Bash or PowerShell with Cloud Shell to work with Azure services. You can use the Cloud Shell preinstalled commands to run the code in this article without having to install anything on your local environment.

To start Azure Cloud Shell:

Option Example/Link
Select Try It in the upper-right corner of a code block. Selecting Try It doesn't automatically copy the code to Cloud Shell. Example of Try It for Azure Cloud Shell
Go to https://shell.azure.com, or select the Launch Cloud Shell button to open Cloud Shell in your browser. Launch Cloud Shell in a new window
Select the Cloud Shell button on the top-right menu bar in the Azure portal. Cloud Shell button in the Azure portal

To run the code in this article in Azure Cloud Shell:

  1. Start Cloud Shell.

  2. Select the Copy button on a code block to copy the code.

  3. Paste the code into the Cloud Shell session by selecting Ctrl+Shift+V on Windows and Linux or by selecting Cmd+Shift+V on macOS.

  4. Select Enter to run the code.

To install and use the CLI locally, this tutorial requires that you run the Azure CLI version 2.0.4 or later. Run az --version to find the version. If you need to install or upgrade, see Install the Azure CLI.

Create a resource group

Create a resource group with the az group create command. An Azure resource group is a logical container into which Azure resources are deployed and managed.

The following example creates a resource group named myResourceGroup.

az group create --name myResourceGroup --location southeastasia

Create a storage account

The sample uploads images to a blob container in an Azure Storage account. A storage account provides a unique namespace to store and access your Azure storage data objects. Create a storage account in the resource group you created by using the az storage account create command.


In part 2 of the tutorial, you use Azure Event Grid with Blob storage. Make sure to create your storage account in an Azure region that supports Event Grid. For a list of supported regions, see Azure products by region.

In the following command, replace your own globally unique name for the Blob storage account where you see the <blob_storage_account> placeholder.


az storage account create --name $blobStorageAccount --location southeastasia --resource-group myResourceGroup --sku Standard_LRS --kind blobstorage --access-tier hot

Create Blob storage containers

The app uses two containers in the Blob storage account. Containers are similar to folders and store blobs. The images container is where the app uploads full-resolution images. In a later part of the series, an Azure function app uploads resized image thumbnails to the thumbnails container.

Get the storage account key by using the az storage account keys list command. Then, use this key to create two containers with the az storage container create command.

The images container's public access is set to off. The thumbnails container's public access is set to container. The container public access setting permits users who visit the web page to view the thumbnails.

$blobStorageAccountKey=$(az storage account keys list -g myResourceGroup -n $blobStorageAccount --query [0].value --output tsv)

az storage container create -n images --account-name $blobStorageAccount --account-key $blobStorageAccountKey --public-access off

az storage container create -n thumbnails --account-name $blobStorageAccount --account-key $blobStorageAccountKey --public-access container

echo "Make a note of your Blob storage account key..."
echo $blobStorageAccountKey

Make a note of your Blob storage account name and key. The sample app uses these settings to connect to the storage account to upload the images.

Create an App Service plan

An App Service plan specifies the location, size, and features of the web server farm that hosts your app.

Create an App Service plan with the az appservice plan create command.

The following example creates an App Service plan named myAppServicePlan in the Free pricing tier:

az appservice plan create --name myAppServicePlan --resource-group myResourceGroup --sku Free

Create a web app

The web app provides a hosting space for the sample app code that's deployed from the GitHub sample repository. Create a web app in the myAppServicePlan App Service plan with the az webapp create command.

In the following command, replace <web_app> with a unique name. Valid characters are a-z, 0-9, and -. If <web_app> is not unique, you get the error message: Website with given name <web_app> already exists. The default URL of the web app is https://<web_app>.azurewebsites.net.


az webapp create --name $webapp --resource-group myResourceGroup --plan myAppServicePlan

Deploy the sample app from the GitHub repository

App Service supports several ways to deploy content to a web app. In this tutorial, you deploy the web app from a public GitHub sample repository. Configure GitHub deployment to the web app with the az webapp deployment source config command.

The sample project contains an ASP.NET MVC app. The app accepts an image, saves it to a storage account, and displays images from a thumbnail container. The web app uses the Microsoft.Azure.Storage, Microsoft.Azure.Storage.Blob, and the Microsoft.Azure.Storage.Auth namespaces from the Azure Storage client library to interact with Azure storage.

az webapp deployment source config --name $webapp --resource-group myResourceGroup --branch master --manual-integration --repo-url https://github.com/Azure-Samples/storage-blob-upload-from-webapp

Configure web app settings

The sample web app uses the Azure Storage Client Library to request access tokens, which are used to upload images. The storage account credentials used by the Storage SDK are set in the app settings for the web app. Add app settings to the deployed app with the az webapp config appsettings set command.

az webapp config appsettings set --name $webapp --resource-group myResourceGroup --settings AzureStorageConfig__AccountName=$blobStorageAccount AzureStorageConfig__ImageContainer=images AzureStorageConfig__ThumbnailContainer=thumbnails AzureStorageConfig__AccountKey=$blobStorageAccountKey

After you deploy and configure the web app, you can test the image upload functionality in the app.

Upload an image

To test the web app, browse to the URL of your published app. The default URL of the web app is https://<web_app>.azurewebsites.net.

Select the Upload photos region to select and upload a file, or drag a file onto the region. The image disappears if successfully uploaded. The Generated Thumbnails section will remain empty until we test it later in this topic.

Upload Photos in .NET

In the sample code, the UploadFiletoStorage task in the Storagehelper.cs file is used to upload the images to the images container within the storage account using the UploadFromStreamAsync method. The following code sample contains the UploadFiletoStorage task.

public static async Task<bool> UploadFileToStorage(Stream fileStream, string fileName, AzureStorageConfig _storageConfig)
    // Create storagecredentials object by reading the values from the configuration (appsettings.json)
    StorageCredentials storageCredentials = new StorageCredentials(_storageConfig.AccountName, _storageConfig.AccountKey);

    // Create cloudstorage account by passing the storagecredentials
    CloudStorageAccount storageAccount = new CloudStorageAccount(storageCredentials, true);

    // Create the blob client.
    CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();

    // Get reference to the blob container by passing the name by reading the value from the configuration (appsettings.json)
    CloudBlobContainer container = blobClient.GetContainerReference(_storageConfig.ImageContainer);

    // Get the reference to the block blob from the container
    CloudBlockBlob blockBlob = container.GetBlockBlobReference(fileName);

    // Upload the file
    await blockBlob.UploadFromStreamAsync(fileStream);

    return await Task.FromResult(true);

The following classes and methods are used in the preceding task:

Class Method
CloudStorageAccount CreateCloudBlobClient
CloudBlobClient GetContainerReference
CloudBlobContainer GetBlockBlobReference
CloudBlockBlob UploadFromStreamAsync

Verify the image is shown in the storage account

Sign in to the Azure portal. From the left menu, select Storage accounts, then select the name of your storage account. Select Containers, then select the images container.

Verify the image is shown in the container.

Azure Portal listing of images container

Test thumbnail viewing

To test thumbnail viewing, you'll upload an image to the thumbnails container to check whether the app can read the thumbnails container.

Sign in to the Azure portal. From the left menu, select Storage accounts, then select the name of your storage account. Select Containers, then select the thumbnails container. Select Upload to open the Upload blob pane.

Choose a file with the file picker and select Upload.

Navigate back to your app to verify that the image uploaded to the thumbnails container is visible.

In part two of the series, you automate thumbnail image creation so you don't need this image. In the thumbnails container in the Azure portal, select the image you uploaded and select Delete to delete the image.

You can enable CDN to cache content from your Azure storage account. For more information about how to enable CDN with your Azure storage account, see Integrate an Azure storage account with Azure CDN.

Next steps

In part one of the series, you learned how to configure a web app to interact with storage.

Go on to part two of the series to learn about using Event Grid to trigger an Azure function to resize an image.