This is possible, but we don't provide a built in guide for it. You will have to adapt our other
kubernetes instructions. Some key things you will need to change: you should make the proxy listen on a tcp port instead of a unix socket and you will have to set up a kubernetes service to allow other pods to connect to it.
Only do this if you trust all of the workloads on your cluster. You are effectively allowing anything running in the cluster to use that authorization to connect to Cloud SQL. if you have workloads that shouldn't be able to connect to the prod database (for example qa pods which should only be able to connect to a qa DB in case they do damage) then this can't stop them.
David