Yearn vaults maintain a certain buffer to not deployed into a strategy to allow for cheaper deposits/withdrawals.
This keeper bot ensures the buffer is kept as tight as possible by calling earn() on vaults when available / balance > ratio.
It consists of a contract that can batch call earn() on all vaults and a script that determines which vaults need poking.
Import a keystore to Brownie:
brownie accounts import keeper keystore.json
One-off script can be launched like this:
brownie run vault_keeper --network mainnet
It will prompt you to unlock the account and do its magic. If you want to run it headless, it can also load an account from VAULT_KEEPER_PRIV environment variable.