I was reading the book Hybrid Cloud Apps with OCP again – that’s an awesome book by Michael Elder at al, and the only comment I would add is about networking/ DNS. The book could add more about networking and how it changed from OCP 3.x to OCP 4.x.
In some scenarios of lack resource of the kuberntes/ocp nodes, the pod Quality of Service, can play a role on the nodes eviction process and how they can terminate the pods, the types of quality set on the pods, either guaranteed, burstable, and best effort.
We do that on the deployment/deployment config – for usual deployments (no operator) involved.
In an Operator deployment for example, the Infinispan operator, setting the container specs in the Infinispan CR with cpu and memory with the same values will make it guaranteed.
And this setting can have a huge impact on the stability of critical nodes in case the OCP nodes decided to start killing ocp pods. The BestEffort will be the first on the list, followed by Burtable and Guaranteed pods will be the last one on the kill list.
Although a small setting this can have huge consequences for OOME Kill (or avoiding it).