Let's understand first how a trigger works and get acquainted with the different types of triggers available in Azure Functions.

The architecture of a trigger and how it works is shown in the following figure:

The preceding diagram shows the event that fires the trigger and once the trigger is fired, it runs the Azure Function associated with it.

We need to note a very important point here: one function must have exactly one trigger; in other words, one function can't have multiple triggers.

Now let's see the different types of trigger available in Azure:

• TimerTrigger: This trigger is called on a predefined schedule. We can set the time for execution of the Azure Function using this trigger.
• BlobTrigger: This trigger will get fired when a new or updated blob is detected. The blob contents are provided as input to the function.
• EventHubTrigger: This trigger is used for the application instrumentation, the user experience, workflow processing, and in the Internet of Things (IoT). This trigger will get fired when any events are delivered to an Azure event hub. We will discuss this further later in the chapter.
• HTTPTrigger: This trigger gets fired when the HTTP request comes. We will discuss this further later in the chapter
• QueueTrigger: This trigger gets fired when any new messages come in an Azure Storage queue.
• Generic Webhook: This trigger gets fired when the Webhook HTTP requests come from any service that supports Webhooks.
• GitHub Webhook: This trigger is fired when an event occurs in your GitHub repositories. The GitHub repository supports events such as Branch created, Delete branch, Issue comment, and Commit comment.
• Service Bus trigger: This trigger is fired when a new message comes from a service bus queue or topic.