---
title: "Lua"
description: "2 posts about Lua, summarised, each linking to the original."
---

# Lua
> 2 posts about Lua, summarised, each linking to the original.

## Articles

### [How Shopify Dynamically Routes Storefront Traffic](https://yomu.fyi/post/how-shopify-dynamically-routes-storefront-traffic.md)
- Company: [Shopify](https://yomu.fyi/company/shopify.md)
- Author: 2023-10-18
- Published: Apr 9, 2021

Shopify’s Storefront Renderer team rewrote the storefront implementation beginning in 2019 and needed a way to shift traffic between the legacy and new versions while migrating features. Using nginx with OpenResty, Lua modules, a control plane, and the spy chatbot, they moved routing rules from a Lua file into JSON payloads that could be created, updated, enabled, disabled, and deleted without a CI or deployment cycle. Rules selected shops and request subsets through filters, then controlled rendering and verification rates, including forward verification, reverse verification, and self-verification in the nearest region. During nginx request processing, matching occurs in the rewrite phase; verification is scheduled with timers in the log phase so duplicate requests run asynchronously after the client response path. The system supported gradual rollouts, parity checks, and resilience testing under Redis failures, while the team planned to simplify routing after the new storefront served almost all traffic.


### [Pummelling the Platform–Performance Testing Shopify](https://yomu.fyi/post/pummelling-the-platform-performance-testing-shopify.md)
- Company: [Shopify](https://yomu.fyi/company/shopify.md)
- Author: 2023-10-18
- Published: Dec 2, 2020

Shopify prepares for high-traffic sales events such as BFCM by repeatedly simulating customer traffic on representative test shops, aiming to expose bottlenecks before merchants experience them. Its Platform Conditioning team supports service-owning teams with approachable performance-testing tools and processes, distinguishing load tests for known traffic levels from stress tests that push services toward failure. A Go load generator runs Lua flows through lightweight VMs, models realistic traffic shapes and costly endpoints, and can issue tens of millions of requests per minute or more. Tests are initiated through Slack using the internal ChatOps tool Spy, which returns links to dashboards, logs, and results. Cronograma provides formal experiments with hypotheses, observations, conclusions, alert detection, Slack timelines, and comparable metrics such as response times, 5xx errors, and requests per minute; the tools have led to performance improvements and give Shopify confidence in future sales events.