January 22, 2024

Avoiding Breakage with Deprecation Warnings

Andrew Lenehan

Well-maintained packages typically include deprecation warnings on features and services that are about to be removed or made obsolete by an upcoming release. Typically, when we see version changes break a codebase, that change could have been remediated had a developer logged and used these warnings effectively before upgrading. In this post, we’ll explore how we use deprecation warnings at Infield to upgrade apps safely.

Logging deprecation warnings

Effective logging of deprecation warnings is an essential aspect of managing dependencies well. Oftentimes, we see deprecation warnings thrown in the course of running a test suite. To ensure we’re getting a comprehensive view of deprecation warnings, we comb runtime deprecation logs to account for any codepaths that aren’t covered by tests. 

Different languages and libraries provide different mechanisms to effectively log deprecations. In Rails, ActiveSupport contains a ‘deprecation.warn’ method that can be configured differently for development, test, and production environments. In Python, the ‘warnings’ module can be similarly configured. Javascript doesn’t have a built-in deprecation warning system, but you can use console methods like ‘console.warn’ or ‘console.error’ to find them.

Using Warnings to Avoid Issues

Once you have deprecation warnings logged, you need to triage them in a way that makes them actionable. Here’s a more strategic approach for using deprecations warnings effectively:

  1. Prioritize: Not all deprecations are equal. Some may pose future security risks, while others may simply lead to suboptimal performance. Assess and prioritize them based on the impact they have on your app.
  2. Cross-Reference the Changelog: If a changelog exists, cross-reference any unclear warnings with changelog entries. The community may have also built tools (codemods, etc) to assist with remediating warnings.
  3. Test: After updating dependencies or removing deprecated features, thoroughly test your application to ensure that everything still works as expected.
  4. Monitor: Even after successfully updating and testing your code, continue to monitor the application. The changelog may list potential side effects or performance impacts that you’ll want to watch out for.

You’ll also want to update regularly to prevent the pile-up of deprecations and the associated technical debt. Infield can help here. Managing deprecations in open source dependencies is a vital part of maintaining a healthy and secure codebase. By paying close attention to deprecation warnings, logging them effectively, and using them to inform your maintenance strategy, you can ensure that your applications remain robust, secure, and up-to-date. If you need some assistance here, feel free to reach out to founders@infield.ai.