gRPC client not using grpc-lb even with load-balancer address

Question

I am trying to load-balance rpc calls to multiple node.js backends from single node.js client using an haproxy load-balancer with TCP-based load-balancing. I am providing this load-balancer's dns-name:port while creating grpc client, which according to https://github.com/grpc/grpc/blob/master/doc/load-balancing.md, should be treated as a load-balancer address and a subchannel should open with each of the lb's backend servers. But I can see that the only channel that opens is with the load-balancer and all the rpc are sent to a single server only, until tcp idle connection-timeout hits and a new tcp connection is setup with a new server.

Just wanted to ask how does grpc detects if the client is connecting with load-balancer or a server? And is there any way to tell the client that the address it is connecting to is a load-balancer address, and hence it should use grpc-lb policy instead of pick-first?

Answer 1

I later understood that for load-balancing policy to figure out if the address fed is of load-balancer or not, it needs an additional boolean indicating if it is an lb-address or not. So I needed to set SRV records for my load-balancer address to have this additional information required by load-balancing policy of grpc, according to this https://github.com/grpc/proposal/blob/master/A5-grpclb-in-dns.md