Blob and file transactions have significantly increased after upgrade to .Net 8 Isolated

Question

Hi all,

We have noticed a significant increase in blob and file transactions, and therefore significant cost increase, since upgrading our function app from .NET 6 In Process model to .NET 8 Isolated. Wondering if anyone has had a similar issue and how you've solved it?

We are not sure what is causing this, since the function app logic and functionality is essentially the same, just upgraded to .Net 8 Isolated.The cost for Blob storage has increased by approximately 300% or more - and it seems the GetBlobProperties API call is the leading cause as it's usage jumps significantly with the upgrade to .Net 8.

We have no Blob trigger functions in our function app. We have HTTP trigger, Service Bus trigger and Timer trigger functions.

What is the easiest/best way to figure out which function(s) is calling GetBlobProperties so often?

When looking at the logs in $logs directory of blob storage, it's basically just line after line of "RenewBlobLease". From what I can tell our function app does not have any diagnostics or logging enabled.

Thanks!

Answer 1

Hello @MTBD

One way to do this is to enable Application Insights for your function app. Application Insights can provide detailed telemetry data about your function app, including information about function invocations and dependencies.

You can use this data to identify which functions are making the most calls to the GetBlobProperties API. To enable Application Insights for your function app, you can follow the steps outlined in this documentation: Monitor Azure Functions with Application Insights. Once you have enabled Application Insights, you can use the Application Insights Analytics tool to query the telemetry data and identify which functions are making the most calls to the GetBlobProperties API.

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