DEVELOPMENT.md

Development

• Prerequisites
• Debug via Blink Developer Tools / node-inspector
• Config file options
• Feature flags
  • How to add a new flag
  • How to configure feature flags
• Run in the cloud
  • Initial setup (one time per developer machine)
  • Create/update AWS EC2 cluster
• Dive in development

Install

You may need Python 2.X (required by node-gyp, only for building).

git clone https://github.com/leapdao/leap-node.git
cd leap-node
yarn

Run

To connect to the testnet

DEBUG=tendermint,leap-node* node index.js --config=https://testnet-node.leapdao.org

Run local network

Use leap-sandox. It is the easiest way to start local leap network at the moment.

Alternative guide how to manually set up a local environment (may be outdated)

Debug via Blink Developer Tools / node-inspector

Start node with --inspect and port 9999 for example:

$ node --inspect=9999 /path/to/leap-node <usual args>

You can connect to the debugger via chrome://inspect in the Chrom{ e, ium } browser, or with tools like node-inspector.

Connecting to Remote host using ssh:

$ ssh -vNL9999:127.0.0.1:9999 <user@remote host>...

Your local port 9999 forwards now to the remote host on address 127.0.0.1 and port 9999.

Config file options

  "bridgeAddr": "0x7b8342412883f4b34f335d4e1391ec190eb887ca",
  "operatorAddr": "0x9b83018de826c0343af6e682c24e7c91a421755c",
  "exitHandlerAddr": "0x0b32eb1aaa9b0804852f4fe1b2e6100edb4533d8",
  "rootNetwork": "https://rinkeby.infura.io",
  "rootNetworkId": 4,
  "network": "leap-testnet-gamma",
  "networkId": 1341,

• bridgeAddr — Bridge proxy contract address
• operatorAddr — Operator proxy contract address
• exitHandlerAddr — ExitHandler proxy contract address
• rootNetwork — (optional, maybe specified via CLI args) root chain provider url (e.g. https://rinkeby.unfura.io)
• rootNetworkId — NetworkId (called also chainId) of the network.
• network — leap network name
• networkId - leap network ID
• flagHeights — (optional) flag → height mapping to enable feature flags only on certain heights (see feature flags section)
• genesis — genesis string in Tendermint format
• peers — array of peers in Tendermint format

Feature flags

If you want to introduce breaking changes (it can break existing networks) in tx checks you should wrap these changes into condition with feature flag to avoid resync problems.

if (bridgeState.flags.tx_should_fail_on_zero_input) {
  if (valueOf(input) === 0) {
    throw new Error('WTF');
  }
}

How to add a new flag

1. Add it into FLAGS array here
2. That’s all, you can use it. It will be true by default

How to configure feature flags

1. Add flagHeights section into the network config

2. Add activation height:

   {
     ...,
     "flagHeights": {
       "tx_should_fail_on_zero_input": 5000,
     }
   }

3. Until this height flag will be false, after (inclusively) — true

Run in the cloud

⚠️ this section is probably outdated

You can use Terraform to spin up an Amazon EC2 instances with the node. You will need an SSH keypair to access the EC2 instance. Generate a new keypair or use an existing one.

Initial setup (one time per developer machine)

terraform init setup/cloud

This will read an existing cluster state from leap-node-state S3 bucket (make sure you have one).

Create/update AWS EC2 cluster

terraform apply -var ssh_public_file="~/.ssh/leap-testnet.pub" -var ssh_private_file="~/.ssh/leap-testnet" -var network="leap-testnet-gamma" -var count=4 -var leap_node_version=3.1.0-0 setup/cloud

This will set up 4 EC2 instances (and all the required infrastructure) running leap-node version 3.1.0-0 using presets/leap-testnet-gamma.json network config. If instances are already running, it will update them if leap_node_version or network file changed.

Some useful commands once it is up and running:

• check the logs: ssh ubuntu@<ec2 host> journalctl -u leap-node
• start/stop/restart/status: ssh ubuntu@<ec2 host> sudo service leap-node start/stop/restart/status