how to keep asp.net core web api app always ON to avoid cold/idle issue hosted in AKS

Question

I have bunch of asp.net core web api apps running in AKS and below is the observation:

• First api request of the day completes in 5009ms.
• Subsequent request within few seconds completes in 367ms

After 20 minutes When again I making API call,

• First call took again 2590ms, why? Is this cold start behavior? how to avoid it?
• Subsequent calls completes in 372ms

I came to know we have some solution for it in App Service where I can make service ALWAYS ON to avoid delay in API response after idle time.

Question is, what are solution for AKS deployed web api's? Will liveness prob will help here (so far I havn't used it)?

Answer 1

@Mohammad Ajmal Yazdani , we regret the delay and any inconvenience it might have caused. We tried reproducing this behavior without much success. However, if you are observing this, as you have correctly pointed out, liveness probes is the best shot telling Kubernetes to restart the container if critical functionality is impaired.

The kubelet uses liveness probes to know when to restart a container. For example, liveness probes could catch a deadlock, where an application is running, but unable to make progress. Restarting a container in such a state can help to make the application more available despite bugs.

You can refer to this blog which does a good job of explaining how you can set up your liveness probe health check.

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Hope this helps.

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