websocket-proxy

websocket-proxy fans out flashblock streams from one or more upstream builders to connected clients. It handles Brotli compression, API key authentication, and per-IP rate limiting.

Package

• Crate name: websocket-proxy-bin
• Binary name: websocket-proxy
• Source: bin/websocket-proxy
• Library: crates/infra/websocket-proxy
• Dockerfile: etc/docker/Dockerfile.websocket-proxy

Architecture

The proxy operates as a fan-out service:

Upstream 1 ─┐
Upstream 2 ─┤→ websocket-proxy ─→ Client A
Upstream N ─┘                  ─→ Client B
                               ─→ Client N

It connects to one or more upstream WebSocket URIs (e.g., builder nodes producing flashblocks) and fans out the messages to all connected downstream clients. This enables horizontal scaling of flashblock delivery.

Features

Feature	Description
Fan-out	Multiplexes messages from upstream sources to all connected clients
Brotli compression	Compresses WebSocket frames for bandwidth-efficient delivery
API key auth	Authenticates clients via API keys before allowing connections
Per-IP rate limiting	Prevents abuse by limiting connection rates per source IP
Metrics	Exposes Prometheus metrics on port 9000
Multiple upstreams	Connects to multiple upstream URIs for redundancy

Ports

Port	Protocol	Purpose
8545	WebSocket	Client-facing flashblock stream
9000	HTTP	Prometheus metrics

Key Dependencies

• websocket-proxy — Core proxy logic
• brotli — Brotli compression
• futures — Async stream utilities
• hostname — Hostname resolution
• tokio — Async runtime

Docker

# Build the image
docker build -t websocket-proxy -f etc/docker/Dockerfile.websocket-proxy .

# Run
docker run -it --rm \
  -p 8545:8545 \
  -p 9000:9000 \
  websocket-proxy [OPTIONS]

Build

cargo build --bin websocket-proxy --release

Usage

./target/release/websocket-proxy [OPTIONS]

Source

View source on GitHub