Azure Function App Dropping Triggers with no Trace

Question

Hello,

I have an azure function app and every 20 to 30 days it drops all of my timer triggers without any warnings/errors or traces. Im using the linux flex consumption function app with SAMI access to the storage account where the function logic/code is stored. This was the case even with the storage account key/string. I have another function app as well that is unrelated to this one that has never had this issue with the exact same configuration. Do you have any suggestions?

Best Regards,

Cole

Answer 1

Hi @Cole Duprey ,

Thanks for reaching out to Microsoft Q&A.

Here are a few suggestions that might help you troubleshoot and hopefully resolve this problem:

1. Check Host Startup Logs: It's essential to see if there are any host startup exceptions that could be causing the triggers to drop. If you have Application Insights enabled, you can run the following query to see if the host is failing to start:

   
      exceptions
   
      | where customDimensions.Category == "Host.Startup"
   
   

2. Look for Logs in Log Analytics Workspace: If you've specified a Log Analytics workspace during the App Service cluster extension installation, you can retrieve App Service logs with the following query:

   
      AppServiceConsoleLogs_CL
   
      | where AppName_s =~ "*MyFunctionAppName*"
   
      | where Log_s contains "FunctionAppLogs"
   
   

3. Check for Competing Function Apps: Ensure that no other Function App is pulling messages from the same queue or is configured to perform similar timer functions. This could lead to one app appearing idle.
4. Investigate Sync Trigger Issues: If you're using Azure Functions on Container Apps, ensure that the expected scale rule is present. Check your container app logs for sync trigger operations:

   
      let appName =~ "<app name>";
   
      let environment =~ "<DefaultDomainPrefix>";
   
      ContainerAppConsoleLogs_CL
   
      | where ContainerAppName_s =~ appName
   
      | where EnvironmentName_s =~ environment
   
      | extend logJson = parse_json(Log_s)
   
      | where logJson.Summary contains "synctriggers" or logJson.Summary contains "settriggers"
   
   

5. Function Configuration: Review your function trigger configurations to make sure everything is set correctly and check if there are any external factors affecting your function app, such as networking issues, incorrect configurations, or missing dependencies.

For additional troubleshooting, you might also want to explore:

• Investigating and Reporting Issues with Timer Triggered Functions
• Timer Trigger Troubleshooting

Hope this helps!

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Answer 2

It sounds like you're experiencing an issue with your Azure Function App where timer triggers are dropping without any trace or warning. Here are a few suggestions to troubleshoot and potentially resolve the issue:

1. Check Storage Account Access: Since you mentioned using SAMI access, ensure that the function app has the necessary permissions to access the storage account. If the app loses access to the storage account, it can lead to issues with triggers.
2. Review Function App Configuration: Verify that your function app is configured correctly, including the runtime and language versions, as well as any connection strings for triggers. Misconfigurations can cause triggers to fail.
3. Monitor Application Insights: If you have Application Insights enabled, check for any failure events or performance issues that might provide clues about why the triggers are dropping.
4. Diagnose and Solve Problems: Use the "Diagnose and solve problems" feature in the Azure portal for your function app. This tool can help identify issues related to availability and performance.
5. Check for Cold Start Issues: In a consumption plan, cold start issues can affect the responsiveness of your function app. Review your concurrency settings and ensure that your app is optimized for cold starts.
6. Logs and Monitoring: Utilize the logs in the Azure portal to run Kusto queries and check for any errors or warnings that might not be immediately visible. This can help identify any underlying issues that aren't apparent at first glance.

If the problem persists, consider reaching out to Microsoft support with detailed logs and information about your configuration for further assistance.

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References:

• Resolve common runtime issues after deployment
• Resolve issues when creating, deleting, or restoring Azure Function App