I am running GKE cluster version 1.20 in which Dataplane V2 and the Network Policy features are disabled.
Per the GKE documentation, enabling the Network Policy feature on non-Dataplane V2 clusters requires recreating all node pools.
My cluster have two node pools for various workloads and I want to make sure pod A can communicate only with pod B, both on the same node pool, without recreating the other node pool.
I also want to avoid achieving this using OS-based solutions such as Linux iptables or GCP-based solutions such as VPC firewall rules. It must be an in-cluster solution.
Dataplane V2 has Network Policies enabled by default, you don't have to enable them
Per the doc
Warning: GKE Dataplane V2 comes with Kubernetes network policy enforcement built-in. This means that you don't need to enable network policy in clusters that use GKE Dataplane V2. If you try to explicitly enable or disable network policy enforcement in a cluster that uses GKE Dataplane V2, the request will fail with the error message Enabling NetworkPolicy for clusters with DatapathProvider=ADVANCED_DATAPATH is not allowed..