Eclair is a scala implementation of the Lightning Network. Eclair is french for Lightning.

This software follows the BOLT specifications, therefore it is compatible with Blockstream's lightning-c.

---

Overview

This software creates a node compatible with a Lightning network and provides a GUI to manage the node. A JSON-RPC API is available if you prefer to run it headless.

Available actions:

• Open a channel with another eclair or lightningd instance
• Display opened channels with the node (status, balance, capacity, ...)
• Receive payments from another node
• Send payments to another node

Installation

The project is under heavy development and no release is available yet. Still you can download the sources, compile the project with Maven (cf §Development) and run it on localhost.

---

Development

Set up the environment

• JDK 1.8+
• Latest Scala installation
• Maven
• A segwit version of bitcoin core in testnet or regtest mode

⚠️ eclair currently runs on regtest/segnet only. Do not try and modify it to run on bitcoin mainnet!

• Make sure that bitcoin-cli is on the path and edit ~/.bitcoin/bitcoin.conf and add:

server=1
regtest=1
rpcuser=***
rpcpassword=***

Run

• Download the sources and build the executable JAR with the following command:

mvn package -DskipTests

• Start bitcoind
• Mine enough blocks to activate segwit blocks:

bitcoin-cli generate 500

• Navigate to eclair-node/target and execute the jar eclair-node_2.11-0.2-SNAPSHOT-xxxxxx-capsule-fat.jar

JVM Options

option	default value	description
eclair.server.port	TCP port	9735
eclair.http.port	HTTP port	8080
eclair.bitcoind.rpcuser	Bitcoin Core RPC user	foo
eclair.bitcoind.rpcpassword	Bitcoin Core RPC password	bar

→ see application.conf for full reference.

Testing with lightningd

→ Checkout our guide

JSON-RPC API

method	params	description
connect	host, port, anchor_amount	opens a channel with another eclair or lightningd instance
list		lists existing channels
addhtlc	channel_id, amount, rhash, locktime	sends an htlc
fulfillhtlc	channel_id, r	fulfills an htlc
close	channel_id	closes a channel
help		displays available methods

---

Project Status

• Network
• Routing (simple IRC prototype)
• Channel protocol
• HTLC Scripts
• Unilateral close handling
• Relaying Payment
• Fee management
• Blockchain watcher
• Storing states in a database

Resources

• [1] The Bitcoin Lightning Network: Scalable Off-Chain Instant Payments by Joseph Poon and Thaddeus Dryja
• [2] Reaching The Ground With Lightning by Rusty Russell

Other implementations

Name	Language	Compatible
Amiko-Pay	Python	no
lightning-c	C	yes
lnd	Go	no
Thunder	Java	no