Standing On the Shoulders of Giants: Unleashing the Power of Scriptable Load Balancers

Every year, our organizations continue adding more services. It’s unsustainable to have a dedicated team of SREs for each one. That’s why, as an industry, we’ve moved to the product-team SRE model. We’re now accustomed to building custom services that applications reach out to, but not middleware services that operate on requests before they reach their destination.

Load balancers have the potential to provide application-aware middleware without making changes to the application itself. However, traditional load balancers can’t be easily and deeply customized or redeployed quickly without significant risk. Instead, we can embed a scripting language to fulfill these requirements.

At Shopify, we do this with Nginx and LuaJIT via OpenResty. Our Nginx scripts deploy in 10 seconds, run through a thorough suite of automated tests, and have allowed us to solve sharding across data centers, handle some of the world’s biggest flash sales, and respond quickly to layer 7 DDoS attacks. What once took a large team of engineers can now be accomplished by one of any size.

The lessons learned from building this middleware framework are applicable to any service. By solving hard problems in your load balancers, you can benefit every application or service you run.