Error getting bitcoin block to process from DB
I had problems like this too and through hours of trial and error, I got it working, Check out my bitcoin and bifrost settings found in repositories here

https://github.com/StellarKit

I can't remember the exact problem, I think I remember I had my rpc urls wrong. 

BIFROST_BITCOIN_RPC_SERVER:         "bitcoind:18332"

bitcoind refers to the bitcoin docker image and uses dockers networking.

But look at the docker-compose.yml files for a working example.

You can install everything I have to get bifrost working on testnet.