ChainBridge

[WIP]

Contents

• Installation
• Configuration
• Running
• Chain Implementations
• Testing
• Simulations

Installation

Dependencies

• Subkey: Used for substrate key management. Only required if connecting to a substrate chain.

  make install-subkey

Building

make build: Builds chainbridge in ./build.

or

make install: Uses go install to add chainbridge to your GOBIN.

Configuration

Note: TOML configs have been deprecated in favour of JSON

A chain configurations take this form:

{
    "name": "eth",                      // Human-readable name
    "type": "ethereum",                 // Chain type (eg. "ethereum" or "substrate")
    "id": "0",                          // Chain ID
    "endpoint": "ws://<host>:<port>",   // Node endpoint
    "from": "0xff93...",                // On-chain address of relayer
    "opts": {},                         // Chain-specific configuration options (see below)
}

See config.json.example for an example configuration.

Ethereum Options

Ethereum chains support the following additional options:

{
    "bridge": "0x12345..."          // Address of the bridge contract (required)
    "erc20Handler": "0x1234..."     // Address of erc20 handler (required)
    "erc721Handler": "0x1234..."    // Address of erc721 handler (required)
    "genericHandler": "0x1234..."   // Address of generic handler (required)
    "gasPrice": "0x1234"            // Gas price for transactions (default: 20000000000)
    "gasLimit": "0x1234"            // Gas limit for transactions (default: 6721975)
    "http": "true"                  // Whether the chain connection is ws or http (default: false)
    "startBlock": "1234"            // The block to start processing events from (default: 0)
}

Substrate Options

Substrate supports the following additonal options:

{
    "startBlock": "1234" // The block to start processing events from (default: 0)
}

Blockstore

The blockstore is used to record the last block the relayer processed, so it can pick up where it left off.

If a startBlock option is provided (see Configuration), then the greater of startBlock and the latest block in the blockstore is used at startup.

To disable loading from the blockstore specify the --fresh flag. A custom path for the blockstore can be provided with --blockstore <path>

Keystore

ChainBridge requires keys to sign and submit transactions, and to identify each bridge node on chain.

To use secure keys, see chainbridge accounts --help. The keystore password can be supplied with the KEYSTORE_PASSWORD environment variable.

To import external ethereum keys, such as those generated with geth, use chainbridge accounts import --ethereum /path/to/key.

To import private keys as keystores, use chainbridge account import --privateKey key.

For testing purposes, chainbridge provides 5 test keys. The can be used with --testkey <name>, where name is one of Alice, Bob, Charlie, Dave, or Eve.

Chain Implementations

• Ethereum (Solidity): chainbridge-solidity

  The Solidity contracts required for chainbridge. Includes deployment and interaction CLI.

  The bindings for the contracts live in bindings/. To update the bindings modify scripts/setup-contracts.sh and then run make clean && make setup-contracts

• Substrate: chainbridge-substrate

  A substrate pallet that can be integrated into a chain, as well as an example pallet to demonstrate chain integration.

Testing

Unit tests require an ethereum node running on localhost:8545 and a substrate node running on localhost:9944. E2E tests require an additional ethereum node on localhost:8546.

A docker-compose file is provided to run two Geth nodes and a chainbridge-substrate-chain node in isolated environments:

$ docker-compose -f ./docker-compose-e2e.yml up

See chainbridge-solidity and chainbridge-substrate-chain for more information on testing facilities.

All Go tests can be run with:

$ make test

Go tests specifically for ethereum, substrate and E2E can be run with

$ make test-eth
$ make test-sub
$ make test-e2e