Relayer service from BBC to BSC

This is an canonical implementation of bsc-relayer service to relay cross chain packages from Binance Chain to Binance Smart Chain. It can also monitor double sign behavior on BSC and submit evidence to Binance Chain. Community members are encouraged to implement more implementations according to their own requirements.

Quick Start

Note: Requires Go 1.19+

Setup config

Edit config/config.json and input your private key to bsc_config.private_key
Transfer enough BNB to this account:
1. 100:BNB for relayer register
2. More than 10:BNB for transaction fee.
Setup relayer mode:
```
{
  
  "competition_mode": true
  
}
```
If competition_mode is true, bsc-relayer will monitor cross chain packages in every block and try to deliver the packages immediately. Otherwise, bsc-relayer will check if there are undelivered packages in every clean_up_block_interval blocks and batch deliver these packages. Competition mode can accelerate package delivery but will cost more transaction fee. In contrary, in non-competition mode, package delivery will be slower but less transaction fee will be cost.

If you want to monitor double sign behavior on BSC, you need to fill more than 1 endpoints in bsc_config.monitor_data_seed_list.

3.1 Testnet monitor_data_seed_list:

{
  "monitor_data_seed_list": [
      "wss://data-seed-prebsc-1-s1.binance.org:8545",
      "wss://data-seed-prebsc-2-s1.binance.org:8545",
      "wss://data-seed-prebsc-1-s2.binance.org:8545",
      "wss://data-seed-prebsc-2-s2.binance.org:8545",
      "wss://data-seed-prebsc-1-s3.binance.org:8545",
      "wss://data-seed-prebsc-2-s3.binance.org:8545"
    ]
}

3.2 Mainnet: monitor_data_seed_list:

{
  "monitor_data_seed_list": [
        "wss://bsc-dataseed1.binance.org:443",
        "wss://bsc-dataseed2.binance.org:443",
        "wss://bsc-dataseed3.binance.org:443",
        "wss://bsc-dataseed4.binance.org:443",
        "wss://bsc-dataseed1.defibit.io:443",
        "wss://bsc-dataseed2.defibit.io:443",
        "wss://bsc-dataseed3.defibit.io:443",
        "wss://bsc-dataseed4.defibit.io:443",
        "wss://bsc-dataseed1.ninicoin.io:443",
        "wss://bsc-dataseed2.ninicoin.io:443",
        "wss://bsc-dataseed3.ninicoin.io:443",
        "wss://bsc-dataseed4.ninicoin.io:443"
    ]
}

Besides, you also need to provide proper Binance Chain mnemonic.

The supported db platforms include mysql and sqlite3. This is an example db config:
```
{
   "dialect": "mysql",
   "db_path": "relayer:12345678@(localhost:3306)/bsc_relayer?charset=utf8&parseTime=True&loc=Local"
}
```
If you don't want to specify a db for your bsc-relayer, just leave db_path to empty.

Send alert telegram message when the balance of relayer account is too low. This is an example alert config:

{
    "enable_alert": true,
    "enable_heart_beat": false,
    "interval": 300,
    "telegram_bot_id": "your_bot_id",
    "telegram_chat_id": "your_chat_id",
    "balance_threshold": "1000000000000000000",
    "sequence_gap_threshold": 10
}

Please refer to telegram_bot to setup your telegram bot. If you don't want this feature, just set enable_alert to false.

Build

Build Binary:

make build

Build Docker Image

Please complete configuration setup in config/config.json first, mainly including rpc endpoints, BSC private key and BC mnemonic(if you want to submit double sign evidence)
Docker build command:

docker build -t bsc-relayer:latest .

Run

Run locally for testnet:

./build/bsc-relayer --bbc-network-type 0 --config-type local --config-path config/config.json

Run locally for mainnet:

./build/bsc-relayer --bbc-network-type 1 --config-type local --config-path config/config.json

Run docker for testnet:

docker run -e BBC_NETWORK=0 -e CONFIG_TYPE="local" -d -it bsc-relayer

Run docker for mainnet:

docker run -e BBC_NETWORK=1 -e CONFIG_TYPE="local" -d -it bsc-relayer

TroubleShooting

Please fill proper bsc private key to bsc_config.private_key, example private key: your_private_key
```
panic: privateKey of Binance Smart Chain should not be empty

goroutine 1 [running]:
```
Please fill your mnemonic to bbc_config.mnemonic, example mnemonic: your_mnemonic
```
ERROR main missing local mnemonic
```

Monitor Relayer Status

To enable this function, you must specify proper db config for your relayer. Suppose 8080 is the admin port:

curl localhost:8080/status

Example response:

{
    "total_tx": 82,
    "success_tx": 36,
    "failed_tx": 46,
    "sync_header_tx": 41,
    "deliver_package_tx": 41,
    "accumulated_total_tx_fee": "0.14336928:BNB",
    "accumulated_success_tx_fee": "0.1030536:BNB",
    "accumulated_failed_tx_fee": "0.04031568:BNB",
    "update_time": "2020-07-14 06:59:39 PM"
}