Function app - "func-process-cpn-ocpi-api-data-ev-prod" failed to trigger on 23-Apr-2025

Question

Function app - "func-process-cpn-ocpi-api-data-ev-prod" failed to trigger on 23-Apr-2025

Anirban Roy Choudhury 0

Linux consumption plan Function app - "func-process-cpn-ocpi-api-data-ev-prod" failed to trigger on 23-Apr-2025. See following exhibit.
User's image

How do we know about such outages in advance?
What mitigation actions can be taken to avoid such issues in future?

3.Do we get some azure credit for almost 24 hrs. of outage?

Khadeer Ali 5,155 Reputation points Microsoft External Staff Moderator

2025-04-24T12:00:15.2366667+00:00
@Anirban Roy Choudhury ,

To address your concerns regarding the function app "func-process-cpn-ocpi-api-data-ev-prod" failing to trigger:

Knowing About Outages in Advance: Azure typically provides notifications about maintenance events and potential outages through the Azure portal and email alerts. Regularly checking the Azure Service Health dashboard can also help you stay informed about any issues affecting your resources.

Mitigation Actions: To avoid such issues in the future, consider implementing the following best practices:

Use the Premium plan for your function app to reduce cold starts and improve availability.

Implement a Warmup trigger to keep your function app ready to respond quickly.

Ensure that you have at least two instances running with Azure App Service Health Check enabled to maintain availability during outages.

Review your function app's scaling settings to ensure it can handle demand effectively.

References:

Best practices for reliable Azure Functions
Anirban Roy Choudhury 0 Reputation points

2025-04-24T14:07:04.6266667+00:00
Hello Khadeer Ali,

Service health notifications doesn't apply to consumption plan function apps so we need alternative approaches here.

Consumption plans don't support Azure App Service Health Check, any alternatives?

This issue happened in a blob triggered linux consumption plan function app. What do you mean by warm up trigger? Can you please provide a reference on this for blob triggered linux consumption function apps?

Consumption plans are supposed to handle scaling automatically?
Khadeer Ali 5,155 Reputation points Microsoft External Staff Moderator

2025-04-28T14:10:57.1566667+00:00

@Anirban Roy Choudhury ,I wanted to check in and see if my earlier response addressed your question. If you still need assistance or have additional questions.
Khadeer Ali 5,155 Reputation points Microsoft External Staff Moderator

2025-04-29T10:26:13.25+00:00

@Anirban Roy Choudhury ,

Just following up again to see if you were able to check the suggestions or if there's anything else I can assist you with.
LeelaRajeshSayana-MSFT 17,766 Reputation points Moderator

2025-05-01T17:07:35.74+00:00

@Anirban Roy Choudhury If you are still experiencing the issue, may I know the trigger type the function app is linked with? There was a limitation identified in older versions of Function App due to which the app could not get triggered when the function app name is longer than 32 characters. You can find more details on this bug here - Azure Function not triggered unless restarted/refreshed via Azure Portal · Issue #5970 · Azure/azure-functions-host The underlying issue is because when generating a default host ID, the host name (slot host name) is being used and would be truncated to 32 characters max. This ensures that the generated ID conforms to the core SDK length restrictions. This truncation can open the possibility for naming collisions, particularly in the case of slots. In slot scenarios, if the site name is over 32 characters long and a slot is created that starts with the same 32 characters and is only disambiguated in later characters, both the production and the slot site will be using the same host ID.

As a work around for this issue, starting Function App V2 versions, there is a setting named AzureFunctionsWebHost__hostid which can be passed through environment variables and can be set to a custom name. This enables you to set an explicit HostID in app settings which will allow you to overcome the above stated limitation. Please refer this documentation - Timer trigger for Azure Functions | Microsoft Learn

Please give it a try and let us know if this helps.

1 answer

Your answer

Khadeer Ali 5,155 Reputation points Microsoft External Staff Moderator

2025-04-24T12:00:15.2366667+00:00

@Anirban Roy Choudhury ,

To address your concerns regarding the function app "func-process-cpn-ocpi-api-data-ev-prod" failing to trigger:

Knowing About Outages in Advance: Azure typically provides notifications about maintenance events and potential outages through the Azure portal and email alerts. Regularly checking the Azure Service Health dashboard can also help you stay informed about any issues affecting your resources.

Mitigation Actions: To avoid such issues in the future, consider implementing the following best practices:

Use the Premium plan for your function app to reduce cold starts and improve availability.

Implement a Warmup trigger to keep your function app ready to respond quickly.

Ensure that you have at least two instances running with Azure App Service Health Check enabled to maintain availability during outages.

Review your function app's scaling settings to ensure it can handle demand effectively.

References:

Best practices for reliable Azure Functions
Anirban Roy Choudhury 0 Reputation points

2025-04-24T14:07:04.6266667+00:00

Hello Khadeer Ali,

Service health notifications doesn't apply to consumption plan function apps so we need alternative approaches here.

Consumption plans don't support Azure App Service Health Check, any alternatives?

This issue happened in a blob triggered linux consumption plan function app. What do you mean by warm up trigger? Can you please provide a reference on this for blob triggered linux consumption function apps?

Consumption plans are supposed to handle scaling automatically?
Khadeer Ali 5,155 Reputation points Microsoft External Staff Moderator

2025-04-28T14:10:57.1566667+00:00

@Anirban Roy Choudhury ,I wanted to check in and see if my earlier response addressed your question. If you still need assistance or have additional questions.
Khadeer Ali 5,155 Reputation points Microsoft External Staff Moderator

2025-04-29T10:26:13.25+00:00

@Anirban Roy Choudhury ,

Just following up again to see if you were able to check the suggestions or if there's anything else I can assist you with.
LeelaRajeshSayana-MSFT 17,766 Reputation points Moderator

2025-05-01T17:07:35.74+00:00

@Anirban Roy Choudhury If you are still experiencing the issue, may I know the trigger type the function app is linked with? There was a limitation identified in older versions of Function App due to which the app could not get triggered when the function app name is longer than 32 characters. You can find more details on this bug here - Azure Function not triggered unless restarted/refreshed via Azure Portal · Issue #5970 · Azure/azure-functions-host The underlying issue is because when generating a default host ID, the host name (slot host name) is being used and would be truncated to 32 characters max. This ensures that the generated ID conforms to the core SDK length restrictions. This truncation can open the possibility for naming collisions, particularly in the case of slots. In slot scenarios, if the site name is over 32 characters long and a slot is created that starts with the same 32 characters and is only disambiguated in later characters, both the production and the slot site will be using the same host ID.

As a work around for this issue, starting Function App V2 versions, there is a setting named AzureFunctionsWebHost__hostid which can be passed through environment variables and can be set to a custom name. This enables you to set an explicit HostID in app settings which will allow you to overcome the above stated limitation. Please refer this documentation - Timer trigger for Azure Functions | Microsoft Learn

Please give it a try and let us know if this helps.

Answer 1

@Anirban Roy Choudhury ,

Thanks for the follow-up. You're right — service health notifications and App Service Health Checks don’t apply to function apps running on the Linux Consumption Plan, which does limit some proactive monitoring options.

Here are a few things we can consider as alternatives:

Monitoring: We can enable Application Insights and set up alerts based on log inactivity or failures. For example, if the blob trigger hasn’t logged any activity for a set time, we get notified.
https://learn.microsoft.com/en-us/azure/azure-functions/functions-monitoring?tabs=cmd
Warm-up Trigger: Since blob triggers can’t be called directly, we can add a lightweight timer-triggered function in the same app. This runs periodically (say every 5 minutes) just to keep the function app warm and reduce cold start issues.
https://learn.microsoft.com/en-us/azure/azure-functions/durable/durable-functions-overview?tabs=in-process%2Cnodejs-v3%2Cv1-model&pivots=csharp#monitoring
Auto Healing (New Diagnostics Experience): App Service now supports an Auto Healing feature via App Service Diagnostics, which can take predefined actions (like restarting the app) if unhealthy conditions are detected — though this is more relevant for App Services and Premium plans. Announcing Auto Healing in App Service Diagnostics
Scaling: Consumption Plan does support auto-scaling, but there can be occasional delays if the scale controller is busy, or in rare cases, platform-level issues. Adding retries or fallback logic where possible can help here.
https://learn.microsoft.com/en-us/azure/azure-functions/functions-scale
https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-storage-blob-trigger?tabs=python-v2%2Cin-process%2Cnodejs-v4%2Cextensionv5&pivots=programming-language-powershell#trigger-behavior

If this function app is business-critical, we might also want to consider switching to the Premium Plan, which offers better reliability, warm instances, and more control.

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Function app - "func-process-cpn-ocpi-api-data-ev-prod" failed to trigger on 23-Apr-2025

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