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A company is developing an Azure Function App that processes images uploaded to Azure Blob Storage. The function needs to be triggered whenever a new image (JPG or PNG) is added to a specific container. The solution must minimize costs and ensure that the function is only active when new images arrive. Which trigger type should the Azure Function use?

  1. AQueue Trigger
  2. BBlob Trigger
  3. CHTTP Trigger
  4. DTimer Trigger
Show answer & explanation

Correct answer: B. Blob Trigger

An Azure Blob Trigger is specifically designed to execute an Azure Function whenever a new or updated blob is detected in a specified container. This aligns perfectly with the requirement to process images upon upload, minimizing costs by only running when needed.

Why the other options are wrong

  • A. A Queue Trigger responds to messages added to an Azure Storage Queue, not directly to blob uploads.
  • C. An HTTP Trigger responds to HTTP requests and wouldn't automatically detect blob uploads.
  • D. A Timer Trigger executes on a schedule, not in response to blob uploads.

Azure Function Blob Trigger

An Azure Function trigger that runs code in response to new or modified blobs in Azure Storage.

  • Automatically invoked when a blob is created or updated.
  • Supports binding to input and output blobs.
  • Cost-effective for event-driven storage processing.

Memory trick: Triggers are the starting gun for your Azure Functions.

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