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How to run functionality only sometimes in an Azure function

Time:02-23

I have an Azure function with a trigger to make it run once every 15 minutes:

TimerTrigger("0 */15 * * * *", RunOnStartup =false)

Within this function, there is some functionality that I only want to run once per hour. I am currently checking the minute of the current time to see whether it should run or not. But as I understand it, Azure function triggers are not always precise (this is running on a consumption-based app service), so instead I am checking for a range of minutes.

int currentMinute = DateTime.Now.Minute;
bool extraFunctionality = (currentMinute >= 58 && currentMinute <= 2);

This seems like it will work; only running this functionality during the ":00" runs, once per hour. However, it looks like bad code to me, for a couple reasons:

  • The up to 2 minutes early and 2 minutes late number was chosen pretty much arbitrarily; I don't have a good idea of what sort of time span to use there.
  • It relies on using DateTime.Now which will return different results depending on server settings, even though I don't care about anything other than the current minute.
  • The code simply doesn't read like the intent is to get it to run once per hour.

Is there a better / more proper way to do this within Azure functions? Can I either get information from the TimerInfo parameter or the ExecutionContext parameter about which 15-minute trigger caused the function to run? Or can I have a separate TimerTrigger which runs once per hour, and then have different functionality based on which of the 2 timers caused the function to trigger? Or is there some way to have the TimerTrigger itself pass in a parameter telling me which 15-minute window it is in?

Or, is my code fine as-is; perhaps with some adjustment to the number of minutes I allow it to be off?

CodePudding user response:

You could create two Azure Functions, one which runs at 15, 30, 45 minutes past the hour and another which runs on the hour. Then in each of these functions set a variable for if it's runnin on the hour.

[FunctionName("HourlyFunction")]
public static void RunHourly([TimerTrigger("0 0 15,30,45 * * *")]TimerInfo myTimer, ILogger log)
{
    _myService.Run(true);
}

[FunctionName("FifteenMinuteFunction")]
public static void RunEveryFifteen([TimerTrigger("0 0 * * * *")]TimerInfo myTimer, ILogger log)
{
    _myService.Run(false);
}

Then have a separate service which can be called by those functions:

public class MyService : IMyService
{
    public async Task Run(bool isHourlyRun)
    {
        // Do work here
    }
}

* I'm not sure those cron expressions are correct

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