Boltlight - a BOLT-on interface to the Lightning Network

Boltlight is a Lightning Network node wrapper.

It is not a LN node itself and connects to an existing node of one of the supported implementations, providing a uniform interface and set of features. Client code that uses boltlight can thus be agnostic on which node is running under the hood.

This means that the underlying LN node implementation can be changed anytime with minimal intervention and no effects on client code.

Each underlying implementation implements some features with "little" differences. Boltlight strives to keep a uniform interface at all times, drawing a common line where implementations differ and always choosing to stay BOLT-compliant as much as possible.

LAPP developers should be free to code, without the need to lock-in to any particular implementation.

Supported LN implementations ⚡

Currently, the main LN implementations ¹ are supported:

• c-lightning (v0.10.1) by Blockstream
• eclair (v0.6.1) by Acinq
• electrum (v4.1.5) by Thomas Voegtlin
• lnd (v0.13.3-beta) by Lightning Labs

How it works

On the client side, boltlight exposes a gRPC client interface, by default on port 1708. On the node side, it proxies all the received calls to the underlying implementation, using the appropriate transport and authentication to connect and applying the appropriate format and data translations to each implemented call.

See Supported APIs for a table of the supported calls for each implementation.

Calls that are not yet implemented return an UNIMPLEMENTED error.

Software dependencies and configurations are the only significant differences between the supported implementations.

See Implementation Specific for an incomplete list of configuration tips and nuances that are dependent on the particular lightning implementation.

Notes

1. at the moment, only the specified versions of the LN nodes are supported

Requirements

First of all, boltlight will need to connect to an existing and supported LN node.

In order to run boltlight it needs to be configured and software dependencies have to be met. Some dependencies and configuration choices are determined by the implementation of choice. Availability of the required dependencies will be checked at runtime.

The supported architectures are amd64 and arm32v7. The latter may require additional dependencies.

System dependencies

• Linux ^1,2
• Python 3.9+ ³
• [optional] libscrypt 1.8+ (faster start)

Resources

Resource demand should be pretty low:

• CPU: 1 core
• RAM: ~64MB when idling
• disk: docker image weights ~350MB

Notes

1. tested on Debian 10 Buster
2. macOS should work but is not well tested, Windows may work but is not actively supported
3. tested with python 3.9+

Installing

Boltlight can be installed with:

$ pip install boltlight

Usage of a virtualenv is recommended.

Configuring and securing

Boltlight needs to be configured before it can connect to a LN node and make itself useful. Configuring contains all the instructions on how to configure boltlight.

One last step is necessary after configuration is complete: security.

On the node side, as with configuration, this partially depends on the chosen implementation. On the client side, authorization is handled with gRPC macaroons.

For faster setup and execution, TLS and macaroons can be turned off. This is not suitable for production use but can be useful for testing or development.

To configure the necessary secrets and set a password to manage and protect them run:

$ boltlight-secure

It can be run interactively or unattended and will create or update boltlight's database and macaroon files.

All secrets will be encrypted and stored in the database, so they won't be accessible at rest. Secrets are decrypted with boltlight's password as part of the unlocking process, will only be available to boltlight at runtime and are never written to disk in plaintext.

Please read Security for all the details.

Using

Running

To start boltlight run:

$ boltlight

This will start its gRPC server, through which Boltlight can be operated.

The boltlight.proto defines the structure for the data to be serialized and can be found here. gRPC client libraries for supported languages can be generated from this file. See the Generation instructions for more information.

The proto file contains three services: Unlocker, Lightning and Locker. The first does not require macaroon authorization and can only unlock boltlight, the other two start after boltlight is unlocked, require authorization and provide all the supported operations, locking included.

API documentation

Documentation for the gRPC APIs along with example code in Python, Go, Node.js and Bash can be found at API page.

CLI

A CLI named blink, with bash and zsh completion support, is available for interactive usage, maintenance or testing.

To activate completion support add the appropriate line to your shell's RC file:

• ~/.bashrc: . /path/to/installed/boltlight/share/complete-blink.bash
• ~/.zshrc: . /path/to/installed/boltlight/share/complete-blink.zsh

For a full list of the available CLI commands use the --help option:

$ blink --help

Pairing

To pair boltlight with a client, run:

$ boltlight-pairing

This will generate two URIs that allow easy retrieval of connection data (boltlightconnect://<host>:<port>[?cert=<PEM certificate>]) and macaroon (macaroon:<chosen macaroon>). The URIs can be displayed as QR codes, suitable for easy reading from client apps, or as text for easy copying.

The Globular Android wallet is an example app that supports pairing with boltlight.

The fork

Boltlight has been forked from Lighter and continues on the same path, aiming to:

• make it easier to get started
• add support for more implementations
• keep the existing support up-to-date
• add more features

Boltlight is not 100% backwards-compatible with Lighter because of the name change, so a re-configuration is needed in order to upgrade.

Contributing

All contributions are welcome!

If you're a developer and want to get involved, see CONTRIBUTING.md for info on how to join the effort.

If boltlight is missing that key feature you need, please get in touch. Feel free to open issues to request new features or report bugs, or send an email to hashbeam@protonmail.com.