CODEWITHSUNDEEP
azureazure-functionsazure-application-insightsazure-monitoring
Eugene Farnsworth
Eugene Farnsworth

Reputation: 48

Azure Function monitor alert where execution count < 1 never triggered

I have an Azure Function App with Azure Functions that I individually want to monitor with the following rule: If an Azure Function didn't execute for N amount of minutes, send out an email/notification.

I am wondering if this is possible with the Application Insights Alerts, which does provide signal logic for the count on an individual Azure Function basis. But this count is never 0, in the graphs it appears that any count < 0 is not seen as a number. It displays as --, as you can see in the graph for my test function below:

testfunction chart (don't have enough reputation to post images)

The peak on the chart is seen as a 3, but if I use the condition "Whenever the testfunction Count is Less than 1" then the alert is never triggered.

Changing the aggregation granularity doesn't really do much, since the signal logic doesn't ever seem to record a count of 0, or any count smaller than 1.

There are lots of (slightly) more inconvenient ways to do this type of monitoring, but it seemed very possible with the nice built-in Azure Application Insights Alerts and I'd like to use that if at all possible.

Am I trying to misuse Application Insights Alerts or is there something obvious that I'm not getting? I would think it should be possible to have monitoring rules based on a lack of executions.

Upvotes: 1

Views: 2139

Answers (1)

John Gardner
John Gardner

Reputation: 25106

you might have to do this with log/query alerts instead. If you're doing metric based alerts, some of those don't send 0's as data. so if nothing happened during a time range, there's no 0's to alert on, since nothing is submitting 0, 0, 0, 0.

instead, you'd create alerts based on queries: https://learn.microsoft.com/en-us/azure/azure-monitor/platform/alerts-unified-log

the doc has this exact scenario listed:

In some cases, you may want to create an alert in the absence of an event.

For example, a process may log regular events to indicate that it's working properly. If it doesn't log one of these events within a particular time period, then an alert should be created. In this case, you would set the threshold to less than 1. [emphasis added, this is your scenario, correct]?

Example of Number of Records type log alert

Consider a scenario where you want to know when your web-based App gives a response to users with code 500 (that is) Internal Server Error. You would create an alert rule with the following details:

Query: requests | where resultCode == "500"

Time period: 30 minutes

Alert frequency: five minutes

Threshold value: Greater than 0

in that example the query would end up being something like requests | where timespan < ago(30m) | where resultCode == "500" because of the time period set. (the query itself can then filter that time range/result set down however you want)

so for yours, you'd probably just do requests with no where condition at all, and whatever time period and frequency you have, and "less than one" as the threshold. you could make much more complicated queries as well, to filter out test data, etc.

one thing to watch out for is that I believe log alerts will fire an alert every time the frequency elapses. so if you had a requests < 1 alert set up for every 5 minutes, and your function had no calls for 2 hours, the alert is going to fire every 5 minutes, sending you 40 emails or whatever. maybe you want that :)

Upvotes: 2

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