Deterministic Regression Triage in Jenkins: Isolating Failures from the Last Known-Good Baseline

Azeem Siddiqui published details on a structured triage methodology alongside the Build Change Investigator plugin for Jenkins, designed to automate regression analysis across build histories. Rather than forcing engineers to inspect isolated build logs, the workflow establishes a baseline from the last known-good build and isolates the sequence of source code management (SCM) changes up to the first matching failure within a bounded window of up to 100 builds. The plugin deterministically analyzes structured compiler diagnostics, Java stack traces, test failures, and API linkage errors, ranking suspicious commits based on source paths and build-module boundaries. In large engineering organizations running busy CI pipelines, consecutive builds frequently fail due to rapid commits or cascading dependency shifts. When a developer inspects only the latest failed run (such as build #873 after builds #870 through #872 have also failed), they routinely waste time triaging commits merged after the breakage originally occurred. By strictly enforcing baseline comparisons against the last successful build and tracking persistent failure signatures, this deterministic approach eliminates false-lead chasing, optimizes developer focus, and accelerates incident resolution across enterprise build infrastructure. Over the past several release cycles, the DevOps ecosystem has explored generative AI assistants and LLM-driven log summarizers to assist triage. However, probabilistic models often generate plausible hallucinations or struggle when critical runtime metadata is missing from console output. The Build Change Investigator represents a pragmatic architectural shift back toward deterministic telemetry: extracting concrete stack frames and pairing them directly with version control diffs before layering optional AI summarization. This highlights a growing platform engineering trend toward reliable, explainable CI diagnostics. For Jenkins administrators and platform teams, adopting baseline-driven triage requires configuring log and artifact retention policies that preserve diagnostic metadata across multi-build failure streaks. Teams should evaluate the Build Change Investigator plugin to reduce friction during debugging, especially in complex multi-module codebases where subtle dependency linkage errors occur. Practitioners should also ensure build configurations emit structured error signatures to maximize automated change ranking and eliminate manual log parsing.