The Gravity Bridge module has two major data flows, one from Ethereum to Gravity Bridge and one from Gravity Bridge to Ethereum.
Every validator runs the gbt orchestrator command which provides the Ethereum -> Gravity Bridge flow. Relayers
provide the Gravity Bridge -> Ethereum data flow by reading data from the Gravity Bridge module and submitting it as Ethereum transactions.
To understand more see the relaying rewards of the Gravity Bridge documentation.
mkdir gravity-bin
cd gravity-bin
wget https://github.com/Gravity-Bridge/Gravity-Bridge/releases/download/v1.9.2/gbt
chmod +x *
sudo mv * /usr/bin/
mkdir gravity-bin
cd gravity-bin
wget https://github.com/Gravity-Bridge/Gravity-Bridge/releases/download/v1.9.2/gbt-mac-amd64
chmod +x *
Download gbt
You will need to open a terminal and nagivate to the directory where these files where downloaded before running any commands.
There are two primary classes of relaying rewards. One are batch fees, which are always denominated in the same token type as the batch is relaying and the other is Validator set update rewards, which will issue Graviton once the community votes to enable it.
You can read more about relaying rewards section of the Gravity docs.
info.gravitychain.io displays a live view of batches and potential rewards from relaying.
There are two major modes of relaying, continuous and spot. Continuous relayers montior the chain and attempt to relay any profitable batch. Spot relayers want to relay a specific token type or even a specific batch to the exclusion of any others.
Relaying for Gravity Bridge is not risk free. Only put as much ETH into your relayer as you are willing to lose.
Spot relaying is the less risky of the two options, because there's no chance of repeated failures draining your wallet. You should use an information site like info.gravitychain.io to find specific batches you think are profitable and then relay them following the spot relaying instuctions below. Spot relayers will not get a chance to relay very common token types like USDC and USDT as continuous relayers will pounce on this immeidately. Spot relaying is reserved for tokens originating on Cosmos that don't have a well defined value or path to sale on Ethereum.
The fundamental challenge of continous relaying is that all relayers are competing to submit the same transactions to get the reward. Because it's impossible to know in advance with transactions an Ethereum miner will decide to include in a block there is no way to avoid the risk of your TX failing because someone else claimed the relaying reward first. Unfortunately due to the design of Ethereum relayers must pay for their failed transactions and since the batch arguments are quite large the failed tx will have a gas cost on the order of 100k gas.
The way to manage this risk is to reduce the probability that you and another relayer both submit the same transaction batch or valset at the same time. The best way to do this would involve some advanced mempool inspection and history inspection to determine how many other relayers are active. This becomes extremely complicated for batches, where relayers may have a specific interest in different assets, so they each have to be tracked distinctly.
Right now there is only one knob to tune. After running gbt init you can edit ~/.gbt/config.toml and modify the relayer_loop_speed.
[relayer]
relayer_loop_speed = 600
We can do some math to show how relayer_loop_speed translates to expected collisions. Assuming a constant 15 second block period for Ethereum.
expected number of collisions = (num relayers - 1 ) * (block time / relayer_loop_speed)
For a 17 second loop time and two relayers we expect .88 collisions
For a 600 second loop and two relayers we expect .025 collisions
For a 600 second loop and one hundred relayers we expect 2.5 collisions
Hopefully this makes it clear that setting the relayer_loop_speed to a lower value presents a lower risk, but also a lower chance of receiving a reward.
The --token argument accepts human readable names for all Cosmos tokens bridged to Ethereum and some common ERC20 tokens. Values like usdc or USDT will work. You can also use an ERC20 address directly or an ibc/HASHVALUE denom directly
The spot relayer can optionally automatically request batches (requires sending a tx on the Gravity Bridge chain) all you need is the private key phrase containing 1ugraviton to initialize the account since there is no min fee. Add the options --cosmos-phrase "your private key phrase containing graviton here" and --fees 0ugraviton if you would like to do this.
gbt client spot-relay \
--ethereum-key 0xYOURKEYHERE \
--token nymIn order to relay you must provide an Ethereum address containing some funds.
Your relayer can optionally automatically request batches (requires sending a tx on the Gravity Bridge chain) all you need is the private key phrase containing 1ugraviton to initialize the account since there is no min fee. Add the options --cosmos-phrase "your private key phrase containing graviton here" and --fees 0ugraviton if you would like to do this.
gbt init
gbt relayer \
--ethereum-key 0xYOURKEYHERE \
--cosmos-grpc https://gravitychain.io:9090 \
--ethereum-rpc https://eth.althea.net \
--gravity-contract-address "0xa4108aA1Ec4967F8b52220a4f7e94A8201F2D906"