ChainBridge

Contents

• Installation
• Configuration
• 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)
    "maxGasPrice": "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>. For development, the --latest flag can be used to start from the current block and override any other configuration.

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.

Metrics

Basic metrics and a health status check can be enabled with the --metrics flag (default port 8001, use --metricsPort to specify).

The endpoint /health will return the current block height and a timestamp of when it was processed. If the timestamp is at least 120 seconds old an error will be returned.

Prometheus metrics are served on /metrics.

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.

Docs

MKdocs will generate static HTML files for Chainsafe markdown files located in Chainbridge/docs/

make install-mkdocs: Pull the docker image MkDocs

make mkdocs: Run MkDoc's docker image, building and hosting the html files on localhost:8000

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