kryptonhq/arc repository overview

⁠Arc

Arc is a self-hosted realtime messaging server: persistent WebSocket connections, channel-based pub/sub, presence, and a signed HTTP API that application backends call to publish events.

Arc speaks the Channels protocol, version 7, so existing client SDKs for that protocol (JavaScript, iOS, Android, Flutter) and the Python server SDK used from Django work against it by changing the host and credentials only.

• Source, issues and full documentation: https://github.com/kryptonhq/arc⁠
• Licence: Apache-2.0

⁠Tags

Each tag is a multi-architecture image for linux/amd64 and linux/arm64, and is started against a throwaway Postgres in CI before publishing, so a tag that exists has booted at least once.

⁠Running it

Arc needs Postgres and an OpenID Connect provider for dashboard sign-in. Migrations run automatically at startup, so a fresh database plus this image is a working install.

docker run -p 4000:4000 \
  -e DATABASE_URL=postgres://arc:arc@postgres:5432/arc \
  -e SECRET_KEY_BASE=$(openssl rand -base64 48 | head -c 64) \
  -e ARC_ENCRYPTION_KEY=$(openssl rand -base64 32) \
  -e PHX_HOST=arc.example.com \
  -e ARC_OIDC_ISSUER=https://keycloak.example.com/realms/arc \
  -e ARC_OIDC_CLIENT_ID=arc-dashboard \
  -e ARC_OIDC_CLIENT_SECRET=... \
  -e [email protected] \
  kryptonhq/arc:latest

For a complete local stack — Arc, Postgres, a pre-configured Keycloak, and a Next.js demo app — clone the repository and run docker compose up.

Keep ARC_ENCRYPTION_KEY safe and backed up. It encrypts every app secret, encryption master key and webhook secret at rest. If it is lost, those secrets cannot be recovered and every app must be issued new credentials.

⁠Configuration

The full list, including cluster and limit settings, is in the repository README.

⁠Health and metrics

• GET /health/live — 200 while the VM is running
• GET /health/ready — 200 once migrations are applied and the app cache is warm
• GET /metrics — Prometheus text format

TLS is expected to terminate at a proxy in front of Arc, which must forward WebSocket upgrade headers.