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Comment by outworlder | Hacker News Reader

> What yields the lowest risk - spending a ton of time hardening one cluster, or building multiple clusters to reduce the blast radius of bugs and misconfigurations?

Not sure this is a valid dichotomy.

If you are spinning up multiple clusters, you are presumably doing so in an automated fashion. If so, then the effort of hardening is very similar. It doesn't really matter where you do it.

Multiple clusters may have a smaller blast radius, but will have a larger attack surface. Things may be shared between them (accounts? network tunnels? credentials to a shared service?) in which case an intrusion in one puts everyone else at risk.

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> If so, then the effort of hardening is very similar. It doesn't really matter where you do it.

Nope. If the clusters are separate it limits how damaging a compromise of the cluster is. This is why cloud providers don’t stick you on the same k8s cluster as another tenant.

> Multiple clusters may have a smaller blast radius, but will have a larger attack surface. Things may be shared between them (accounts? network tunnels? credentials to a shared service?) in which case an intrusion in one puts everyone else at risk.

It’s not really clear what you’re trying to say here. If someone compromises credentials shared between all clusters that’s the same as compromising credentials used by one mega cluster.

> Nope. If the clusters are separate it limits how damaging a compromise of the cluster is.

But if the clusters are configured similarly, a flaw in one is likely present in the others. GPs point is that if you invest in hardening, you can easily apply it to multiple clusters.

> It’s not really clear what you’re trying to say here.

I assume they mean having more clusters present means there are more opportunities to be compromised (e.g. more credentials to leak, more API servers to target, possible version skew, etc.).

> But if the clusters are configured similarly, a flaw in one is likely present in the others.

That doesn’t matter. The point is that you isolate applications/tenants into different clusters. So if someone exploits their own, they haven’t gained access to some other application.

> assume they mean having more clusters present means there are more opportunities to be compromised (e.g. more credentials to leak, more API servers to target, possible version skew, etc.).

That doesn’t even make sense though. In our strawman scenario these are cookie cutter things. Many is not more vulnerable than one in this case.

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