SOLVED: What Are Function Apps in Azure

An Azure Function App is a service within Microsoft Azure that allows you to run small pieces of code, known as functions, in a serverless environment, which keeps costs down and reliability up.

You can think of Azure Function Apps as equivalent to a Scheduled Task on a Windows computer.

What Are the Use Cases For an Azure Function App?

One of the most popular use cases for an Azure Function App is processing file uploads. This involves using Azure Functions to handle files as they are uploaded to Azure Blob Storage. For example, a function can be triggered when a new file is uploaded, allowing you to validate, transform, and process the file in real-time.

Other common use cases include:

• Sending notifications and reminders: Automatically send emails or push notifications based on specific events
• Scheduled tasks: Run tasks at scheduled intervals, such as database cleanups or backups
• Data processing: Process data streams from IoT devices or other sources in near real-time
• Lightweight APIs: Create simple APIs for web or mobile applications to interact with backends

What Can Trigger a Function App?

Azure Function Apps can be triggered by a variety of events. Here are some common triggers:

1. Timer Trigger: Runs a function on a schedule, similar to a cron job. This is ideal for periodic tasks like data cleanup or sending reminders
2. HTTP Trigger: Invokes a function via an HTTP request. This is useful for creating APIs or responding to webhooks
3. Blob Storage Trigger: Executes a function when a new or updated blob is detected in Azure Blob Storage. This is often used for processing uploaded files
4. Queue Storage Trigger: Fires when a new message is added to an Azure Queue Storage. This is useful for processing background tasks
5. Event Grid Trigger: Responds to events from Azure Event Grid, such as resource changes or custom events
6. Service Bus Trigger: Activates a function when a message is received in an Azure Service Bus queue or topic
7. Cosmos DB Trigger: Runs a function when there are changes in an Azure Cosmos DB collection. This is useful for real-time data processing

These triggers allow developers and IT admins to build flexible and scalable solutions that respond to various events and data changes.

How Much Do Function Apps Cost?

The cost of an Azure Function App depends on the hosting plan you choose. Here are the main options:

Consumption Plan:

Pricing: You pay based on the number of executions and the resources consumed (measured in GB-seconds). This plan includes a monthly free grant of 1 million requests and 400,000 GB-seconds of resource consumption.
Use Case: Ideal for applications with variable or unpredictable workloads.

Premium Plan:

Pricing: Billed based on the number of instances and the memory provisioned. For example, the Premium V2 tier costs $0.532 per hour.
Use Case: Suitable for applications requiring enhanced performance, VNET integration, or longer execution times.

Dedicated (App Service) Plan:

Pricing: Uses regular App Service plan billing, which is based on the chosen pricing tier3.
Use Case: Best for applications needing dedicated VMs, custom images, or isolation.

Flex Consumption Plan (in preview as of Aug 2024):

Pricing: Combines on-demand and always-ready instances. Includes a monthly free grant of 250,000 executions and 100,000 GB-seconds of resource consumption4.
Use Case: Offers flexibility with dynamic scaling and VNET integration.

For a typical usage scenario, the Consumption Plan is often the most cost-effective, especially if your function app has variable workloads. You can use the Azure Pricing Calculator to get a more precise estimate based on your specific needs.