Chapter 25. Scriptable Load Balancers

When scalability problems occur, there’s no time to go back and rearchitect or refactor an entire web service. Inevitably the service you’re responsible for will go down as a result of being overloaded. Sometimes, you’re hoping for a miracle in the form of an easily fixable, bad database query. Or maybe you’re able to simply scale up the number of workers. But what about when you don’t have the time, money, or people needed for solving the problem at hand? Luckily, there’s a new suite of tools that are making a name for themselves in small corners of our industry that can forever change the way we approach scalability and our roles as SREs: scriptable load balancers.

Scriptable load balancers are proxies that can have their request/response processing flow modified through a scripting language such as Lua. This opens new ways for infrastructure teams to shard applications, mitigate Distributed Denial of Service (DDoS) attacks, and handle high load. Small teams can now solve difficult or seemingly impossible problems in novel and elegant ways. The ability to add high-performance, custom logic to a load balancing tier isn’t new; however, the ability to do that at an organization of any size is. And that’s why scriptable load balancers could be game changing.

Scriptable Load Balancers: The New Kid on the Block

Look at almost any web service, and often you’ll find a load balancer being the first ...

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