Sōzu

What is Sōzu?

Sōzu is a reverse proxy for load balancing, written in Rust. Its main job is to balance inbound requests across two or more clusters backends to spread the load.

• It serves as a termination point for TLS sessions. So the workload of dealing with the encryption is offloaded from the backend.

• It can protect the backends by preventing direct access from the network.

• It returns some metrics related to the traffic between clients and backends clusters behind it.

Introduction

• Getting started

• Configure Sōzu

• Configure the Sōzu CLI

• How to use it

• Why you should use Sōzu

• Design Motivation

• Recipes

Overview

• Architecture Overview

• Tools & Libraries

• Lexicon

Operating Sōzu

• Configure Sōzu

• Admin operations & worked examples

• Observability — logs, metrics, audit log

• Debugging strategies

• Benchmarks

• Rate limit design

Going deeper

• H2 Mux Internals — Developer reference for the HTTP/2 multiplexer implementation

• H2 Mux LIFECYCLE.md — In-tree state-machine reference, maintained alongside the code

• UDP LIFECYCLE.md — In-tree flow/state-machine reference for the UDP datapath (userland conntrack, NAT return, teardown, hardening), maintained alongside the code

• Health Checks

• Lifetime of a session

Testing

• Testing guide — the testing doctrine: assertion-first + deterministic simulation, categories, and what every change must land with

• Worker upgrade e2e tests

• Deterministic simulation (UDP) — FoundationDB/VOPR-style seeded fault injection for the sans-io UDP core

• Nightly CI notes

Release Notes

• Changelog

Presentations & Slides

• Sōzu, a hot reconfigurable reverse HTTP proxy by Geoffroy Couprie

• (FR) Refondre le reverse proxy en 2017 pour faire de l’immutable infrastructure. by Quentin Adam