kairo

Standalone Discord audio sending node, written in Rust. Drop-in Lavalink v4 compatible: the same REST API, the same WebSocket events, the same encoded track format.

Why this exists

Kairo started as a hobby project. We wanted more control over the audio node we use, so we decided to build our own.

We have a lot of respect for Lavalink and the people behind it. The protocol and ecosystem it built gave us a solid foundation to work from. Without Lavalink, Kairo probably wouldn't exist.

Kairo isn't here to replace Lavalink. It's simply our own take on the problem, built because we wanted to learn, experiment, and make something of our own.

Running

Docker is the supported way to run it.

curl -O https://raw.githubusercontent.com/bongo-devs/Kairo/main/application.yml.example
mv application.yml.example application.yml

docker run -d --name kairo -p 2333:2333 \
  -v "$PWD/application.yml:/app/application.yml:ro" \
  -v "$PWD/logs:/app/logs" \
  ghcr.io/bongo-devs/kairo:latest

Or, from a clone of this repository:

cp application.yml.example application.yml
docker compose up -d

The node serves port 2333 and reads /app/application.yml. Set KAIRO_CONFIG to read it from somewhere else.

Configuration

Every key is documented inline in application.yml.example. The blocks:

• server, lavalink.server: the listener, the client password, the frame buffer, the filters.
• sources: which platforms are enabled, and their limits and credentials. A source that only resolves metadata plays through sources.mirror.
• lyrics: the providers to query. Disabled leaves the lyrics endpoints unmounted.
• logging: level, per-module overrides, format, and optional rolling file output.
• metrics.prometheus: off until configured.

Every block is optional and falls back to its own defaults. All endpoints except the Prometheus one require the configured password in the Authorization header.

Companion services

• yt-cipher, https://github.com/bongo-devs/yt-cipher, solves the signature cipher and mints the poTokens SABR playback needs. Configured under sources.youtube.remoteCipher. Use this fork rather than the upstream project, which exposes different endpoint names.
• keys-api, https://github.com/bongo-devs/keys-api, is a shared credential store for the Deezer arl, YouTube OAuth tokens and cookies. Configured under sources.keysApi, and sources take their credentials from there instead of the config file. Optional for Deezer, which otherwise rotates the ARLs listed in sources.deezer.arls, and for YouTube OAuth. A YouTube cookie jar comes from here only.

Credits

The REST API, the WebSocket events and the encoded track format are those of Lavalink by Freya Arbjerg and its contributors, which defines the v4 protocol this node implements and which every compatible client was written against. Lavalink is MIT licensed; its notice is reproduced in LICENSE.

License

MIT. See LICENSE, which also carries the third-party notice for Lavalink.