Create a function triggered by Azure Blob storage

Learn how to create a function triggered when files are uploaded to or updated in Azure Blob storage.

View message in the logs.

Prerequisites

Create an Azure Function app

  1. Select the New button found on the upper left-hand corner of the Azure portal, then select Compute > Function App.

    Create a function app in the Azure portal

  2. Use the function app settings as specified in the table below the image.

    Define new function app settings

    Setting Suggested value Description
    App name Globally unique name Name that identifies your new function app. Valid characters are a-z, 0-9, and -.
    Subscription Your subscription The subscription under which this new function app is created.
    Resource Group myResourceGroup Name for the new resource group in which to create your function app.
    OS Windows Serverless hosting is currently only available when running on Windows. For Linux hosting, see Create your first function running on Linux using the Azure CLI.
    Hosting plan Consumption plan Hosting plan that defines how resources are allocated to your function app. In the default Consumption Plan, resources are added dynamically as required by your functions. In this serverless hosting, you only pay for the time your functions run. When you run in an App Service plan, you must manage the scaling of your function app.
    Location West Europe Choose a region near you or near other services your functions access.
    Storage account Globally unique name Name of the new storage account used by your function app. Storage account names must be between 3 and 24 characters in length and may contain numbers and lowercase letters only. You can also use an existing account, which must meets the storage account requirements.
  3. Select Create to provision and deploy the function app.

  4. Select the Notification icon in the upper-right corner of the portal and watch for the Deployment succeeded message.

    Define new function app settings

  5. Select Go to resource to view your new function app.

Tip

Having trouble finding your function apps in the portal, try adding Function Apps to your favorites in the Azure portal.

Function app successfully created.

Next, you create a function in the new function app.

Create a Blob storage triggered function

  1. Expand your function app and click the + button next to Functions. If this is the first function in your function app, select Custom function. This displays the complete set of function templates.

    Functions quickstart page in the Azure portal

  2. In the search field, type blob and then choose your desired language for the Blob storage trigger template.

    Choose the Blob storage trigger template.

  3. Use the settings as specified in the table below the image.

    Create the Blob storage triggered function.

    Setting Suggested value Description
    Name Unique in your function app Name of this blob triggered function.
    Path samples-workitems/{name} Location in Blob storage being monitored. The file name of the blob is passed in the binding as the name parameter.
    Storage account connection AzureWebJobsStorage You can use the storage account connection already being used by your function app, or create a new one.
  4. Click Create to create your function.

Next, you connect to your Azure Storage account and create the samples-workitems container.

Create the container

  1. In your function, click Integrate, expand Documentation, and copy both Account name and Account key. You use these credentials to connect to the storage account. If you have already connected your storage account, skip to step 4.

    Get the Storage account connection credentials.

  2. Run the Microsoft Azure Storage Explorer tool, click the connect icon on the left, choose Use a storage account name and key, and click Next.

    Run the Storage Account Explorer tool.

  3. Enter the Account name and Account key from step 1, click Next and then Connect.

    Enter the storage credentials and connect.

  4. Expand the attached storage account, right-click Blob containers, click Create blob container, type samples-workitems, and then press enter.

    Create a storage queue.

Now that you have a blob container, you can test the function by uploading a file to the container.

Test the function

  1. Back in the Azure portal, browse to your function expand the Logs at the bottom of the page and make sure that log streaming isn't paused.

  2. In Storage Explorer, expand your storage account, Blob containers, and samples-workitems. Click Upload and then Upload files....

    Upload a file to the blob container.

  3. In the Upload files dialog box, click the Files field. Browse to a file on your local computer, such as an image file, select it and click Open and then Upload.

  4. Go back to your function logs and verify that the blob has been read.

    View message in the logs.

    Note

    When your function app runs in the default Consumption plan, there may be a delay of up to several minutes between the blob being added or updated and the function being triggered. If you need low latency in your blob triggered functions, consider running your function app in an App Service plan.

Clean up resources

Other quick starts in this collection build upon this quick start. If you plan to work with subsequent quick starts, tutorials, or with any of the services you have created in this quick start, do not clean up the resources.

Resources in Azure refers to function apps, functions, storage accounts, and so forth. They are grouped into resource groups, and you can delete everything in a group by deleting the group.

You created resources to complete these quickstarts. You may be billed for these resources, depending on your account status and service pricing. If you don't need the resources anymore, here's how to delete them:

  1. In the Azure portal, go to the Resource group page.

    To get to that page from the function app page, select the Overview tab and then select the link under Resource group.

    Select the resource group to delete from the function app page.

    To get to that page from the dashboard, select Resource groups, and then select the resource group that you used for this quickstart.

  2. In the Resource group page, review the list of included resources, and verify that they are the ones you want to delete.

  3. Select Delete resource group, and follow the instructions.

    Deletion may take a couple of minutes. When it's done, a notification appears for a few seconds. You can also select the bell icon at the top of the page to view the notification.

Next steps

You have created a function that runs when a blob is added to or updated in Blob storage.

Learn how to create functions with other kinds of triggers or how to integrate functions with other Azure services.

For more information about Blob storage triggers, see Azure Functions Blob storage bindings.