Learning CI Configuration Correctness for Early Build Feedback

Continuous Integration (CI) allows developers to check whether their code can build successfully and pass tests across various system environments with every commit. To use a CI platform, a developer must provide configuration files within a code repository to specify build conditions. Incorrect configuration settings lead to CI build failures, which can take hours to run, wasting valuable developer time and delaying product release dates. Debugging CI configurations is a slow and error-prone process. The only way to check the correctness of CI configurations is to push a commit and wait for the build result. We present VeriCI, the first system for localizing CI configuration errors at the code level. VeriCI runs as a static analysis tool, before the developer sends the build request to the CI server. Our key insight is that the commit history and the corresponding build histories available in CI environments can be used both for build error prediction and build error localization. We leverage the build history as a labeled dataset to automatically derive customized rules describing correct CI configurations, using supervised machine learning techniques. To more accurately identify root causes, we train a neural network that filters out constraints that are less likely to be connected to the root cause of build failure. We evaluate VeriCI on real world data from GitHub and achieve 91% accuracy of predicting a build failure and correctly identify the root cause in 75% of cases. We also conducted a between-subjects user study with 20 software developers, showing that VeriCI significantly helps users in identifying and fixing errors in CI.