Determine the best trigger for your Azure function

An Azure Functions app doesn't do work until something tells it to execute. For example, we could create an Azure Function to send out a reminder text message to our customers before an appointment. If we don't tell the function when it should run, our customers will never receive a message.

Here, you'll examine triggers at a high level and explore the most common types of triggers.

What is a trigger?

A trigger is an object that defines how an Azure Function is invoked. For example, if you want a function to execute every 10 minutes, you could use a timer trigger.

Every function must have exactly one trigger associated with it. If you want to execute a piece of logic that runs under multiple conditions, you need to create multiple functions that share the same core function code.

In this module, we're going to focus on the timer, HTTP, and blob trigger types.

Types of triggers

Azure Functions support a wide range of trigger types. Here are some of the most common types:

Type Purpose
Timer Execute a function at a set interval.
HTTP Execute a function when an HTTP request is received.
Blob Execute a function when a file is uploaded or updated in Azure Blob storage.
Queue Execute a function when a message is added to an Azure Storage queue.
Azure Cosmos DB Execute a function when a document changes in a collection.
Event Hub Execute a function when an event hub receives a new event.

What is a binding?

A binding is a connection to data within your function. Bindings are optional and come in the form of input and output bindings. An input binding is the data that your function receives. An output binding is the data that your function sends.

Unlike a trigger, a function can have multiple input and output bindings.

In the next exercise, we'll run a function on a schedule using a Timer trigger.