Seeing a lot of 404s to /admin/host/ping after turning on automatic scale out in App Service

Ryan McGee 55 Reputation points

I enabled automatic scale out and enforced a scale out limit on some of my app services. Looking at app insights, I see a very steady GET to "/admin/host/ping". I'm assuming that is part of the automatic scale out infrastructure since it started at the same time, but if I turn automatic scale out back off, it continues.

Everything else seems to be working as expected.

Does anyone know how to update the "/admin/host/ping" to hit a different path or any details on what it's doing? I'd like to continue using automatic scale out but this ping has me a little worried.

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. SnehaAgrawal-MSFT 20,396 Reputation points

    @Ryan McGee Thank you for your reply! I did some more research and found out that -

    The 404s are caused by enabling Automatic Scaling and pinging the same endpoint for both Function Apps and Web Apps.

    The issue of 404s to the /admin/host/ping endpoint is expected behavior as this feature is still in Preview. It will not affect scale-out. Only the status code 429 will impact scale-out. Otherwise, scale-out is determined by latency.

    This issue will be fixed in a future release, which will reduce the noise.

    In the meantime, the 404s should not have any negative effect on scaling, except for the noise. These pings are also not a security risk for the app, as they come from the same scale unit that hosts the app.

    I hope this helps.

    Please let us know if further query on this.

    2 people found this answer helpful.

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