Where can we check azure function startup logs in case of failure

Vipin Sharma 121

Sometimes we are not able to start function application and we would to check logs to understand where was function app stuck.

is there any place we can find startup logs? In Diagnose and solve problems section we have Function App Down or Reporting category but that does not show any error.

Typically we face such issues when there is some networking error, e.g. function app is not able to connect with File share due to missing private end point and public access is not allowed

I am using Java based azure functions, premium app service plan.

1 answer

MughundhanRaveendran-MSFT 12,481 Reputation points

2022-03-09T09:53:31.59+00:00

@Vipin Sharma ,

Thanks for reaching out to Q&A.

You can look at the function invocation logs in the console log or under the monitor section of the sepecific function

However if you are very specific about the function host startup operation logs, you will have to look into the Application insights. Under application insights, there are 2 options to explore

Option 1: Transaction search -> filter for Traces under the event type

Option 2. Run query in the log anlytics. Traces table will provide all the details

I hope this helps!
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Vipin Sharma 121 Reputation points

2022-03-09T11:56:21.587+00:00

Hi @MughundhanRaveendran-MSFT

Both the options you suggested show logs for the period function app was up.

I am facing errors during startup, in case startup fails where do we see error?

MughundhanRaveendran-MSFT 12,481 Reputation points

2022-03-09T12:49:37.99+00:00

@Vipin Sharma , If you run the traces table without any filters, you will find all the logs. You should see host startup related errors if there are any.

MughundhanRaveendran-MSFT 12,481 Reputation points

2022-03-22T13:49:29.177+00:00

@Vipin Sharma , You can see the function startup logs in the traces table under the Application insights logs. You can run the query and check. The custom dimensions column in the traces table will give you more details. Feel free to reach out to me if you have any questions or concerns.

Vipin Sharma 121 Reputation points

2022-03-22T14:08:26.73+00:00

traces table is helpful in general but in my case function app had connectivity issue with file share and I could not see this error anywhere. Closest error I could find was in "Diagnose and solve problems" section of portal, "Function App Down or Reporting Errors" category. That also just suggested one liner message connectivity issue with storage account, but it was hard to understand issue because we don't use file share, function app due to some unknown reason was using file share.

I am told MS support teams have some additional logs, probably that should also be shared with portal users, why would someone want to keep logs secret, specifically logs where we have meaningful error messages.
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