ACINQ / eclair

**Eclair** (French for Lightning) is a Scala implementation of the Lightning Network. This software follows the Lightning Network Specifications (BOLTs). Other implementations include core lightning, lnd, electrum, and ldk. --- • Lightning Network Specification Compliance • JSON API • Documentation • Installation • Prerequisite: Bitcoin Core • Installing Eclair • Configuration • Configuration file • Configure Bitcoin Core wallet • Java Environment Variables • Logging • Backup • Docker • Plugins • Testnet usage • Tools • Resources --- Lightning Network Specification Compliance Please see the latest release note for detailed information on BOLT compliance. JSON API Eclair offers a feature-rich HTTP API that enables application developers to easily integrate. For more information please visit the API documentation website. :rotating_light: Eclair's JSON API should **NOT** be accessible from the outside world (similarly to Bitcoin Core API) Documentation Please visit our docs folder to find detailed instructions on how to configure your node, connect to other nodes, open channels, send and receive payments, and help with more advanced scenarios. You will also find detailed guides and frequently asked questions there. Installation Prerequisite: Bitcoin Core Eclair relies on Bitcoin Core to interface with and monitor the blockchain and to manage on-chain funds: Eclair does not include an on-chain wallet, channel opening transactions are funded by your Bitcoin Core node, and channel closing transactions return funds to your Bitcoin Core node. This means that instead of re-implementing them, Eclair benefits from the verifications and optimisations (including fee management with RBF/CPFP, ...) that are implemented by Bitcoin Core. Eclair uses our own bitcoin library to verify data provided by Bitcoin Core. :warning: This also means that Eclair has strong requirements on how your Bitcoin Core node is configured (see below), and that you must back up your Bitcoin Core wallet as well as your Eclair node (see here): • Eclair needs a _synchronized_, _segwit-ready_, **_zeromq-enabled_**, _wallet-enabled_, _non-pruning_, _tx-indexing_ Bitcoin Core node. • You must configure your Bitcoin node to use or (segwit) addresses. If your wallet has "non-segwit UTXOs" (outputs that are neither , or ), you must send them to a or address before running Eclair. • Eclair requires Bitcoin Core 29 or higher. If you are upgrading an existing wallet, you may need to create a new address and send all your funds to that address. Run bitcoind with the following minimal : Depending on the actual hardware configuration, it may be useful to provide increased parameter value for faster verification and parameter value for better handling of API requests on side. Installing Eclair Eclair is developed in Scala, a powerful functional language that runs on the JVM, and is packaged as a ZIP archive. To run Eclair, you first need to install Java. Eclair targets Java 21 and will run on any compatible Java runtime, we recommend that you use OpenJDK 21. Then download our latest release, unzip the archive and run the following command: You can then control your node via eclair-cli or the API. :warning: Be careful when following tutorials/guides that may be outdated or incomplete. You must thoroughly read the official eclair documentation before running your own node. Configuration Configuration file Eclair reads its configuration file, and write its logs, to by default. To change your node's configuration, create a file named in . Here's an example configuration file: Here are some of the most common options: name | description | default value -----------------------------|----------------------------------------------------------------------|-------------- eclair.chain | Which blockchain to use: *regtest*, *testnet*, *signet* or *mainnet* | mainnet eclair.server.port | Lightning TCP port | 9735 eclair.api.enabled | Enable/disable the API | false. By default the API is disabled. If you want to enable it, you must set a password. eclair.api.port | API HTTP port | 8080 eclair.api.password | API password (BASIC) | "" (must be set if the API is enabled) eclair.bitcoind.rpcuser | Bitcoin Core RPC user | foo eclair.bitcoind.rpcpassword | Bitcoin Core RPC password | bar eclair.bitcoind.zmqblock | Bitcoin Core ZMQ block address | "tcp://127.0.0.1:29000" eclair.bitcoind.zmqtx | Bitcoin Core ZMQ tx address | "tcp://127.0.0.1:29000" eclair.bitcoind.wallet | Bitcoin Core wallet name | "" Quotes are not required unless the value contains special characters. Full syntax guide here. → see here for more configuration options. Configure Bitcoin Core wallet Eclair will use the default loaded Bitcoin Core wallet to fund any channels you choose to open. If you want to use a different wallet from the default one, you must set accordingly in your . :warning: Once a wallet is configured, you must be very careful if you want to change it: changing the wallet when you have channels open may result in a loss of funds (or a complex recovery procedure). Eclair will return BTC from closed channels to the wallet configured. Any BTC found in the wallet can be used to fund the channels you choose to open. We also recommend tweaking the following parameters in : Setting these parameters lets you unblock long chains of unconfirmed channel funding transactions by using child-pays-for-parent (CPFP) to make them confirm. With the default parameters, if your node created a chain of 25 unconfirmed funding transactions with a low-feerate, you wouldn't be able to use CPFP to raise their fees because your CPFP transaction would likely be rejected by the rest of the network. You can also configure Eclair to manage Bitcoin Core's private keys, see our guides for more details. Java Environment Variables Some advanced parameters can be changed with java environment variables. Most users won't need this and can skip this secti…