Systems | Development | Analytics | API | Testing

Jared Lynskey recently wrote a sponsored post, trying out Patch with his app, maru. This article is a follow up about using it in production on Fly.io, including any problems he encountered. Last month I moved maru’s over-the-air updates from my own expo-updates server to Codemagic Patch. Everything in that post ran against Patch’s local evaluation stack on my laptop. The section on production was a plan, with a note to myself to replace it once it had actually happened.

How much does it actually cost to self-host over-the-air (OTA) updates? Especially for an app with many millions of users. It’s a useful number to know if you’ve got a growing Expo Updates bill. This article prices an extreme case of 100 million monthly active users (MAU). Here is the monthly cost of hosting Codemagic Patch on DigitalOcean at a few sizes: You can host Patch on any Linux compatible machine, such as an EC2 on AWS or a machine on Fly.io.

For many teams, Bitrise Insights means build duration and failure rate. Those are good starting points to evaluate your CI performance, but they often fall short when it comes to understanding questions about speed and quality.

Traditional CI/CD pipelines relied on determinism, assuming code produced an exact, repeatable output. Generative models and agentic workflows break this model. A single prompt edit or model checkpoint update can pass standard unit tests while causing silent regressions like truncated API payloads or missing parameters five steps downstream. To ship probabilistic AI reliably, engineering teams must redefine what counts as a passing test.

Codemagic Patch ships live updates of HTML, CSS, and JavaScript to Capacitor, Ionic, and Cordova-on-Capacitor apps, without a new store binary. Say a checkout button stops working on some Android 15 devices, and the fix turns out to be four lines of TypeScript. In a Capacitor app, those four lines live in the web layer, inside a WebView, nowhere near native code.

Most AI coding tools run in a Linux container somewhere. Codespaces is Linux. Copilot’s coding agent works in an ephemeral, Actions-powered Linux environment. Nearly every agent framework assumes a container that spins up in seconds. None of them can build your iOS app, or have build cache to speed up the builds, or have simulators that can run tests that you can view.

Selecting load testing tools for your CI/CD pipeline is a lot like picking between a scalpel and a Swiss Army knife. A scalpel – the focused, specialized solution – excels at one job with surgical accuracy. Think of Apache JMeter or Gatling: these tools are designed for deep, targeted testing, offering powerful scripting and low-level protocol support. They let you dial in precise scenarios and slice through performance bottlenecks with fine control.

If you are a React Native engineer, your job isn’t typically about maintaining infrastructure. So “self-hosted OTA” can sound like a trap. Even if your Expo Update bill is hitting six figures, it’s easy to assume that self-hosting isn’t worth the potentially huge time sink. That fear is understandable, but it doesn’t have to play out that way.

Self-hosting OTA updates became common after App Center and CodePush shut down in 2025. CodePush had been the popular free option, but the remaining hosted services easily hitting five or six figure bills for popular apps. For staging-only or use with small user bases, self-hosting is fairly straight forwards. But, as the user base grows, the architecture can start to struggle and bolt on pieces are required.