How to use rpcpooling option

[kannapoix]

LND has an rpcpolling option to fetch transactions from bitcoind via RPC instead of ZMQ. I'm having trouble using this option and getting the following error:

failed to load config: ValidateConfig: unable to load RPC credentials for bitcoind: unable to extract RPC credentials: unable to find zmqpubrawblock in config, cannot start w/o RPC connection

Are there any other options that need to be added along with rpcpolling? I thought if I used rpcpolling, I wouldn't need to set zmqpubrawblock.
When I explicitly add bitcoind.rpccookie, LND starts properly. Without bitcoind.rpccookie, LND loads the cookie from the default location after checking for the existence of ZMQ parameters, which might be the issue.

[guggero]

The error message is a bit misleading. But basically the part that's relevant is unable to extract RPC credentials. It means you don't have the authentication set. So you must set either bitcoind.rpcuser and bitcoind.rpcpass, or bitcoind.rpccookie.

[kannapoix]

@guggero Thanks for your quick reply. I thought that LND would load the cookie file from the default path even if I didn't set any of the options you mentioned. Is that not the case? Or the loading from the default path is failing in this case.

[guggero]

I think the logic that loads the cookie from the default path wasn't updated for the rpcpolling option, so it complains about the missing ZMQ settings. Which I guess is a bug. But that logic is very old and in need of a refactor anyway... You can avoid that by manually specifying the cookie or user/password option.

[kannapoix]

OK, I get it. Thank you!