Timer trigger binding

The Timer trigger allows you to run a function on a schedule. The schedule is defined using a CRON expression or a simpler schedule format.

Overview

A Timer trigger is a background task that runs without any HTTP request or external event. It is ideal for periodic cleanup, data aggregation, or any recurring job.

Example (C#)

using System;
using Microsoft.Azure.WebJobs;
using Microsoft.Extensions.Logging;

public static class TimerTriggerFunction
{
    [FunctionName("TimerTriggerFunction")]
    public static void Run([TimerTrigger("0 */5 * * * *")]TimerInfo myTimer, ILogger log)
    {
        log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");
    }
}

Supported attributes

Attribute	Description
`schedule`	CRON expression that defines the schedule.
`runOnStartup`	If true, the function runs once when the host starts.
`useMonitor`	Enables built‑in monitoring of the timer status.

CRON expression format

The CRON format for Azure Functions has six fields:

{second} {minute} {hour} {day} {month} {day-of-week}

Example: 0 */5 * * * * – every 5 minutes at the start of a minute.

Best practices

Keep the function execution time short; use durable functions for long‑running processes.
Use RunOnStartup cautiously to avoid duplicate work on host restarts.
Monitor failures using Application Insights or the built‑in timer monitor.