Does pulumi operator support high availability ? Is it safe to increase replica set to 3?

Yeah you can but the others will just be hot spares (will compete for a lock).

hot spares like standby? so, just one pod process traffic ? and standby come into game when we loose main pod?

There’s a lease object created with the Kubernetes API, and all replicas race to obtain the lease and become the leader; when the leader terminates, the lease becomes available again.

got it. Thank you @eager-football-6317