Trigger AppInsights alert for custom metrics request rate

Question

I have 3 custom metrics that track the elapsed time of an HTTP request to an external service, so I can see how performant they are. I am able to setup 3 alerts to tell me when they are taking too long, but I would also like to setup alerts to tell me when the request rate is over or under a certain threshold, for each of the 3 calls.

I can see there is a general Request Rate alert, but this applies to the entire app insights resource - which I share with the rest of my company. So if I set up an alert where the request rate >= 100 every 5 seconds, this will be counting not only my 3 requests but also a whole bunch of other requests I don't care about.

I want to end up with something like this, repeated for request B & C:

• Does request A take longer than 3 seconds (avg over the last 5 mins)? - done
• Are there more than 100 requests for request A (avg over the last 5 mins)?
• Are there fewer than 100 requests for request A (avg over the last 24 hours)?

Is this possible? Should I be looking at some other way of dealing with the requests/metrics?

Answer 1

Yes, it is possible. One way to do this is to use the "Custom Log Search" as a signal to an alert, like here:

If you want to test your queries you can do so in Log Analytics (Application Insights -> Search -> Analytics).