Azure Functions billing in the absence of function/host key

1 Mar 2020 1 mins Azure, Azure Functions, Cloud

You might be wondering: “Am I going to be charged when somebody invokes my Azure Function but with wrong or missing key?". Well, some of the attendees on my currently running Azure course had the same question. And I thought it might be worth sharing the answer publicly.

The answer is that you’re not going to be charger for executions without or with wrong key. Simple as that. But as I was playing with that, I found something interesting.

Although the function itself is not executed and HTTP 401 is returned, the CPU load increases as the requests are flowing in. Something to theoretically take into account when doing some capacity planning i.e. when not using consumption plan.

Also, if you’re using Application Insights, you get messages in the “log” about the endpoint being matched. Kind of makes sense.

Jiří Činčura is .NET, C# and Firebird expert. He focuses on data and business layers, language constructs, parallelism, databases and performance. For almost two decades he contributes to open-source, i.e. FirebirdClient. He works as a senior software engineer for Microsoft. Frequent speaker and blogger at www.tabsoverspaces.com.