What are the available interfaces for being able to access the current state of a resource in the execution loop of the Pulumi program? I'm trying to add logic to a coponent resource for RDS that manages read replicas, so that I can let it apply minor version upgrades to the replica before the primary, dependent on whether the engine version specified is greater than the one currently deployed.

Hard to say without more context about your project/stack setup but I would think either determine the version based of the master instance outputs or use the get_instance function. Or determine the replica engine version by applying on the master output for it to work in cases where you don't have any master instance deployet yet - something like.. (not tested btw..)

def determine_replica_engine_version(current: str) -> str:
    if current == "16.1":
        return "16.3"
    return current

replica_version: pulumi.Output[str] = rds_master.engine_version.apply(
    func=lambda version: determine_replica_engine_version(version)
)

Yeah, I ended up using the get_instance approach. https://github.com/mitodl/ol-infrastructure/blob/main/src/ol_infrastructure/components/aws/database.py#L205-L233