OmniBridge faucet service

This service is monitoring transfers executed through the OmniBridge on the xDai chain and reward the tokens recipients with small amount of xdai.

Run by docker CLI

1. Prepare .env file with the following (at least) variables definitons:

   FAUCET_PRIVKEY=cafe...cafe
   JSON_DB_DIR=/db
   INITIAL_START_BLOCK=123

   See below with the variables explanation.

2. Create the directory where the faucet service will store its data.

   mkdir ./db

3. Run the service

   docker run -ti --rm -v $(pwd)/db:/db --env-file .env omnibridge/faucet:latest 

   Note: the source mount point after the key -v is the directory created on the step 2. The destination mount point is the directory specified in the variable JSON_DB_DIR.

Run by docker-compose

1. Create the directory where the faucet service will store its data.

   mkdir ./db

2. Initialize the docker-compose.yml file based on docker-compose.yml.example. Set proper values for the following variables (at least) there: FAUCET_PRIVKEY, JSON_DB_DIR and INITIAL_START_BLOCK.

   Make sure that the source mount point in the volumes section is the directory created on the step 1.

   See below with the variables explanation.

3. Run the service

   docker-compose up -d

Faucet configuration

The following environment variables may be used to configure the faucet behavior:

1. XDAI_RPC - JSON RPC endpoint the faucet uses to monitor OB events and get data. Default: https://xdai.poanetwork.dev.
2. BSC_OB - an address of BSC-xDai OB mediator on the xDai side. Default: 0x59447362798334d3485c64D1e4870Fde2DDC0d75.
3. ETH_OB - an address of ETH-xDai OB mediator on the xDai side. Default: 0xf6A78083ca3e2a662D6dd1703c939c8aCE2e268d.
4. MOONS_EXT - an address of Rinkeby-xDai ERC20-to-ERC677 mediator for MOONs tokens on the xDai side. Default: 0x1E0507046130c31DEb20EC2f870ad070Ff266079.
5. BRICKS_EXT - an address of Rinkeby-xDai ERC20-to-ERC677 mediator for BRICKs tokens on the xDai side. Default: 0xf85b17E64Bc788D0CB1A8c8C87c0d74e520c2A54.
6. FAUCET_PRIVKEY - a private key of an account holding xdai to reward. No default value!.
7. GAS_PRICE - the gas price (in gwei) the faucet uses for reward transactions (pre-EIP1559 transactions). -1 means to use EIP1559 transactions. Default: -1.
8. HISTORICAL_BASE_FEE_DEPTH - number of recent blocks to estimate the base fee as per gas (EIP1559 related). Default: 20.
9. MAX_PRIORITY_FEE - the priority fee per gas (in gwei) used by the faucet (EIP1559 related). Default: 1.
10. MAX_FEE_RATIO - a coefficient to adjust the base fee per gas acquired from the historical data (EIP1559 related). Default: 1.3.
11. FEE_LIMIT - the higher bound of max fee per gas (in gwei) which is used in order to avoid expensive transactions (EIP1559 related). Default: 150.
12. GAS_LIMIT - the gas limit the faucet uses for reward transactions. Default: 30000.
13. REWARD - amount of xdai used as reward. Default: 0.005.
14. POLLING_INTERVAL - amount of time (in seconds) between two subsequent cycles to discover OB transfers and send rewards. Default: 60.
15. INITIAL_START_BLOCK - a block the first faucet's attempt to discover OB transfers starts from. No default value!.
16. FINALIZATION_INTERVAL - a number of blocks starting from the chain head to consider the chain as finalized. Default: 12.
17. JSON_DB_DIR - a directory where the faucet service keeps its data. No default value!.
18. JSON_START_BLOCK - a name of JSON file where the last observed block is stored. Default: faucet_start_block.json.
19. JSON_CONTRACTS - a name of JSON file where addresses of recipient-contracts are stored. Default: xdai-contracts.json.
20. TEST_TO_SEND - make a transaction to itself just after running the service. Default: false.