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I have configured the warm-up on my App Service on IIS by indicating a custom initialization:

<applicationInitialization>
  <add initializationPage="/Home/Warmup?warmup=1"/>
</applicationInitialization>

When automatic Scale-out occurs all the external calls are sent to existing instances, waiting for the new ones to finish warm-up. That's OK.

But I have another App Service in the same Subscription but in another Location that is calling my service without waiting for this warm-up. Logically, these calls are too slow because the warm-up has not yet been carried out.

Why am I having this behavior?

Why are requests from external applications sent to warmed-up instances but requests running from another Azure App Service can be sent to cold instances?

Both apps are in different App Service Plans.

Alpha75
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  • In the **applicationInitialization** section you can specify multiple URL paths that need to be requested in order to warm up your application. Also notice that you can specify the host name to use for the warm up requests (this is optional and if not specified the “localhost” will be used as a host name). – Harshitha Veeramalla Jan 25 '22 at 06:13
  • The warmup is been called as `http://localhots/Home/Warmup?warmup=1`. That is not a problem. The warmup is executed without problems. – Alpha75 Jan 25 '22 at 07:35

1 Answers1

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Finally the calls did not come from another app service. The URL confused me because this service makes exactly the same call.

The culprit was my service's Health Check setting which had this same URL configured.

App Service Health Check should perhaps wait for each instance to warm up before starting to work when starting service or scaling out new instances.

Alpha75
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