The Situation
Say you are a mobile developer tasked with deploying a React Native application using Expo Application Services (EAS) builds and over-the-air (OTA) updates. Your team has set up the EAS build process, and the application is live in the app stores. However, as the user base grows and the application receives real traffic, issues start to arise. Users report unexpected crashes, and the error monitoring tooling begins to log a significant number of errors. The symptom is an increase in crash reports and error logs, costing the team time and resources to investigate and fix. The cost is not only the immediate loss of users but also the potential damage to the application's reputation and the time spent debugging issues that could have been caught earlier.
Why It Happens
EAS builds and OTA updates introduce additional complexity to the deployment process. When the application is built and packaged using EAS, the resulting bundle may behave differently than the development build. Similarly, when OTA updates are applied, the update process can sometimes lead to unexpected issues, such as version mismatches or caching problems. These issues may not be immediately apparent during development or testing but can become significant problems under real traffic. Understanding the potential failure modes and how to detect them early is crucial to maintaining a stable and reliable application.
The Fix, Step by Step
To address the hidden failure modes in EAS builds and OTA updates, follow these steps:
- Implement Comprehensive Logging and Monitoring: Set up logging and monitoring tools to track errors and crashes in the production environment. This includes using services like Sentry or Crashlytics to monitor crash reports and error logs. Confirm that logging and monitoring are working by verifying that errors are being reported correctly and that the team receives notifications for new issues.
- Use EAS Build Hooks: Utilize EAS build hooks to run custom scripts during the build process. This can help catch potential issues before the build is completed. For example, a hook can be used to run automated tests or linting checks. Confirm that the hooks are working by verifying that the scripts run successfully and that any issues are reported.
- Test OTA Updates Thoroughly: Before releasing an OTA update, test it thoroughly using a staging environment. This includes testing the update process itself and verifying that the application behaves as expected after the update. Confirm that the update is working correctly by verifying that the application functions as expected and that no new issues are introduced.
- Monitor Application Performance: Keep a close eye on application performance after an EAS build or OTA update. This includes monitoring metrics such as crash rates, error rates, and user engagement. Confirm that the application is performing well by verifying that these metrics are within expected ranges.
- Automate Testing for EAS Builds and OTA Updates: Automate testing for EAS builds and OTA updates using tools like Detox or Appium. This can help catch issues early in the development process. Confirm that automated testing is working by verifying that tests run successfully and that any issues are reported.
What It Costs, and When Not to Do It
Implementing comprehensive logging and monitoring, using EAS build hooks, testing OTA updates thoroughly, monitoring application performance, and automating testing for EAS builds and OTA updates require additional time and resources. However, the cost of not doing these things can be much higher, as issues that are not caught early can lead to significant problems in production. The trade-off is between the upfront cost of implementing these measures and the potential cost of dealing with issues in production. In general, it is recommended to implement these measures for applications with a large user base or critical functionality.
At Your Level
- Starting out: Focus on setting up comprehensive logging and monitoring, and learn about EAS build hooks and OTA updates.
- Working engineer: Implement automated testing for EAS builds and OTA updates, and monitor application performance closely.
- Senior or staff: Consider the trade-offs between the upfront cost of implementing these measures and the potential cost of dealing with issues in production, and make informed decisions about when to implement them.
- Lead or director: Prioritize the implementation of these measures based on the application's user base, critical functionality, and business requirements.
In the Interview
When asked about EAS builds and OTA updates in an interview, a weak answer might focus on the general benefits of using these technologies without discussing the potential failure modes. A strong answer would discuss the trade-offs, constraints, and failure modes, such as the potential for version mismatches or caching problems, and how to detect them early. For example, "One of the challenges with EAS builds and OTA updates is ensuring that the application behaves correctly under real traffic. To address this, I would implement comprehensive logging and monitoring, use EAS build hooks, test OTA updates thoroughly, monitor application performance, and automate testing for EAS builds and OTA updates." A follow-up question might ask for specific examples of how these measures have been implemented in the past, or how they would be prioritized based on the application's requirements.
Amit Chakraborty is a founding engineer and senior architect — React Native, AI/RAG systems and production architecture. Portfolio: www.amitchakraborty.dev · LinkedIn · GitHub. Open to senior and founding engineering roles, remote worldwide.
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