Missing logs in azure monitor

Question

Hello!
Is there a reason for missing logs in a function app? for some requests the logs are visible, but sometimes they are not shown so I'm wondering what could affect the function logging so that no results are shown.

Not are functions are affected but one service bus trigger that is quite heavily loaded and receives requests night time

Answer 1

Hi,

Thanks for reaching out & posting on MS Q&A. We'd be happy to assist you here and help make your Azure experience a great one!

The reason for the absence of the log messages is probably due to the Test/Run feature not mimicking an actual creation of a blob file that would cause (a) the invoking of your trigger function and (b) capturing of the log messages that you'd then expect to see via the log streaming window. For a quick validation of this behavior, you can spin up an HTTP trigger function and try the Test/Run feature to see if the logs from it show.

For testing the Blob trigger & getting the log messages in the log streaming window, you'll need to actually upload a blob file as detailed in our documentation here: https://learn.microsoft.com/en-us/azure/azure-functions/functions-create-storage-blob-triggered-function#test-the-function

I hope this helps. Please let me know if you have any further questions.

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Answer 2

Hi Zainab,

Issue -->logs were missing from Azure monitor

Solution--> Adding this to sampling Settings in host.json file resolved the issue

"samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request;Trace"
      }

For more details, please check this doc https://learn.microsoft.com/en-us/azure/virtual-wan/how-to-virtual-hub-routing

Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.

Thanks,

Deepanshu