Understanding Internal Load Balancer to Access DigitalOcean Kubernetes Services

Posted on August 17, 2024

As I was following through the tutorial on the same topic (https://docs.digitalocean.com/products/kubernetes/how-to/create-internal-load-balancer/), I have a couple of questions regarding “However, if a node goes down, then the DNS record syncs and the Droplets need to get the updated DNS. This results in some downtime.”.

Does this happens when the CA is adding and removing the nodes too?
How much downtime does this result in?

Thank you.

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Bobby Iliev

August 19, 2024

Accepted Answer

Hey!

I just bought that up internally and can confirm the following:

Yes, this issue would apply when the Cluster Autoscaler removes nodes. It doesn’t matter how the nodes are removed; the effect will be the same. Node additions typically shouldn’t cause issues, but node removals can lead to downtime if requests are routed to deleted nodes before the DNS record is updated and the TTL expires.
The downtime largely depends on how ExternalDNS is implemented, with the configured TTL being the dominant factor. If the TTL is short, downtime should be minimal, but longer TTLs can lead to more noticeable disruptions.

As far as I know this issue is a known trade-off when working with dynamic, autoscaling environments like Kubernetes, particularly when dealing with DNS and load balancers in any cloud environments.

Hope that this helps!

- Bobby