Blob Triggered Azure Function Inconsistent Behavior Across User Groups

Question

There is a Blob storage triggered Azure Function that works when certain users (User set A) update files to the blob storage, but it does not work most of the time for another group of users (User set B) when they load files. Interestingly, if a member of User set A loads a file after User set B has loaded files, the Azure Function gets triggered, and all the files processed by User set B are executed through the Azure Function.

All users are operating within the same VPN, so the cause of this discrepancy remains unclear. This issue is occurring for only this specific Azure Function and not others.

Answer 1

Hi @Rahul Banerjee ,

Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.

The inconsistent behavior of the Blob storage-triggered Azure Function for different user groups may stem from several factors. One possibility is that the function's trigger is experiencing delays in processing changes made by User Group B. This could be due to the way the Azure Functions trigger monitors changes in blob storage. If the trigger isn't detecting changes from User Group B promptly, it may seem to work only when User Group A uploads files afterward.

• Moreover, if multiple Azure Functions are configured similarly, one function might inadvertently "steal" changes from another. This is especially relevant if both user groups are uploading files simultaneously, leading to potential conflicts.

To troubleshoot this issue, you might consider checking the following:

• Ensure there are no other Azure Functions with the same configuration that could be processing the same blobs.
• Investigate how long the function takes to execute to determine if it's causing delays in processing.
• Review the lease collection in the Azure Functions to confirm that there are no unexpected owners that could be affecting the processing of changes.

Also, for your better understanding, please refer to the following documentations:

https://learn.microsoft.com/en-us/azure/azure-functions/storage-considerations?tabs=azure-cli#working-with-blobs

https://learn.microsoft.com/en-us/azure/cosmos-db/nosql/troubleshoot-changefeed-functions#common-scenarios-and-workarounds

https://learn.microsoft.com/en-us/azure/azure-functions/functions-create-storage-blob-triggered-function#create-an-azure-blob-storage-triggered-function

If you find the answer helpful, kindly click "Accept Answer" and upvote it. If you have any further questions or concerns, please feel free to reach out to us. We are happy to assist you.