Understanding TimerTriggers in Azure Functions

Azure Functions are Microsoft’s way of offering serverless computing.

In essence, Azure Functions are just source-code functions, running on PaaS servers, which are triggered by some external mechanism. You just deploy functions and do not care about the infrastructure underneath it.

Multiple programming languages are supported e.g. C#, Javascript, Java to write your function.

Multiple kinds of triggers are available. Most of them are related to some event in another Azure resource. For example, adding a blob in Azure Blob Storage (a BlobTrigger) or receiving a message in an Azure Event Hub can trigger the function (an EventHubTrigger).

A function can also expose an external HTTP endpoint. Then a Rest call on that endpoint triggers the function (HttpTrigger).

All these triggers are scalable. The more triggers are fired on the Azure Function, the more functions are executed. If you choose a consumption plan this can even result in a scale-out on the number of servers (which you do not have configured).

Azure Functions also offers a TimerTrigger. Functions are just triggered by a … timer.

This seems simple but the Timer trigger behaves a little bit differently when executed.

Let’s try to understand the Timer Trigger.