Install go

https://go.dev/doc/install

Setup env variables

Create .env file in the root of the project and add the following variables:

# evm private key in hex format without 0x prefix
WALLET_PRIVATE_KEY=
CHAIN_URL=
# recaptcha is not supported yet
RECAPTCHA_SECRET_KEY="non supported yet"

Setup tokens config

The tokens config is used to define the tokens that the faucet will distribute.

Copy tokensConfig.json from smart-contracts repo after run initFaucet.ts script.

Config must have following struct:

{
  "ZKP": {
    "address": "", // erc20 token-contract address, empty for native token
    "amount": "2000000000000000000" // the amount of tokens to send in wei
  },
  "USDT": {
    "address": "0x1558B7241BCD90c7C7aD7683Bf865b84F004E0a5",
    "amount": "10000000"
  },
  ...
}

Build and run

build:

go build -o faucet-backend ./cmd/main.go

run:

./faucet-backend

Config file

The config file described in config.yaml. The config struct described on config/config.go. The .env config params has higher priority than the config file. The config file has following struct:

db_path: /app/data/faucet.db # Path to the database file

http:
  addr: ":8080" # HTTP api server address
  read_header_timeout: 5s # Timeout for reading the request headers
  read_timeout: 10s # Timeout for reading the request body
  write_timeout: 10s # Timeout for writing the response
  idle_timeout: 60s # Timeout for idle connections
  max_request_size: 5000 # Maximum request size in bytes
  rate_period: 1s # Rate limit period for the HTTP server
  rate_limit: 20 # Rate limit for the HTTP server in requests per second

chain_url:      "" # URL of the Ethereum node (e.g. Infura, Alchemy), described on .env
wallet_private_key: "" # Private key of the wallet in hex format (without 0x prefix) that will be used to send transactions, described on .env
native_token_name: ZKP # Name of the native token, used in the faucet

eth_client_limits:
  rate_limit: 50ms # Rate limit for the Ethereum client in milliseconds
  burst: 20 # Burst limit for the Ethereum client in requests


faucet_limits:
  request_limit: 1h # Time period for the faucet request limit
  nonce_ttl: 30s # Time to live for the nonce in seconds

wallet_settings:
  retries:              5 # Number of retries for sending transactions
  tx_mine_wait:         30s # Time to wait for the transaction to be mined
  gas_limit_multiplier: 120 # Multiplier for the gas limit, used to increase the gas limit for the transaction
  nonce_delay:          100ms # Delay for the get pending nonce in milliseconds
  nonce_max_wait:       10s # Maximum wait time for the next pending nonce in seconds

recaptcha: # recaptcha is not supported yet
  enabled: false
  min_score: 0.5
  timeout: 2s
  deadline: 60s