App Service getting 403 error against /admin/host/ping used in autoscaling.

Jonathan Smith (Admin) 5 Reputation points

I've setup the new automatic Azure Autoscale on an App Service running under a P2V2 plan. The app configuration is pretty simple, not much in it, except for Application Insights key, Always On and Session affinty are off, no IP whitelist inplace. When I perform a load test against the app, autoscale is triggered and additional instances begin to spin up but never become fully functional. In the AI logs I noticed "GET /admin/host/ping " which is an endpoint the auto scaling uses is getting 403 errors. Not sure why. Any experienced this?

Azure App Service
Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
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  1. hossein jalilian 4,040 Reputation points

    Thanks for posting your question in the Microsoft Q&A forum.

    It's possible that the service could be detecting what it perceives as an attack and blocking the client.

    • Rate Limiting
    • Security Rules

    Please check the following articles:

    Quota enforcement

    Please don't forget to close up the thread here by upvoting and accept it as an answer if it is helpful

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  2. VenkateshDodda-MSFT 18,946 Reputation points Microsoft Employee

    @Jonathan Smith (Admin) Thanks for your patience on this and thanks for sharing the requested details.

    I have checked with App service Engineering team on this and sharing the below.

    There is no effect for any pings to /admin/host/ping returning any 400-level status code (e.g. 4xx) in automatic scaling logs. You can ignore those as well which doesn't have any impact on the application performance.”

    I hope the answer helps. Please let me know if you have any further queries.

    Please accept as Yes if the answer provided is useful, so that you can help others in the community looking for remediation for similar issues.ngineering team on this and sharing the below.

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