Range Analysis
Analyze an entire range of commits between two SHAs to get a comprehensive view of what changed across multiple deploys.
Range analysis extends commit analysis to cover an entire span of commits. Instead of inspecting a single SHA, you provide a base and head commit, and BlameTrail analyzes every commit in that range. This is especially useful when investigating incidents that may have been caused by changes spread across multiple deploys.
Running a range analysis
- Navigate to Analyses in the sidebar.
- Click Range Analysis.
- Fill in the fields:
- Repository -- Select the repository from the dropdown.
- Base SHA -- The starting commit (exclusive). This is the last known-good commit.
- Head SHA -- The ending commit (inclusive). This is typically the commit deployed when the incident was detected.
- Click Analyze Range.
BlameTrail resolves the commit range using the GitHub API and analyzes each commit individually, then aggregates the results into a unified report.
What the range analysis produces
Per-commit breakdown
Each commit in the range receives its own analysis, including file classifications, risk scores, and a diagnosis. You can expand any commit to see its full details.
Aggregated view
The range analysis also produces a summary that spans the entire range:
- Cumulative file risk -- Files that were modified in multiple commits may accumulate higher risk scores across the range.
- Cross-commit patterns -- The analysis identifies patterns that only become visible when looking at the full range, such as a migration introduced in one commit and a dependent application change in another.
- Top suspects -- A ranked list of the highest-risk files across all commits in the range.
When to use range analysis
Range analysis is most valuable in these scenarios:
| Scenario | Why range analysis helps |
|---|---|
| Multi-deploy incidents | The incident started after several deploys shipped in quick succession. Range analysis covers all of them at once. |
| Rollback investigation | You rolled back to a known-good commit. Use that as the base and the broken commit as the head to see everything that changed. |
| Release review | Before cutting a release, analyze the full range of commits since the last release to identify high-risk changes. |
| Post-mortem | During a post-mortem, use range analysis to document exactly what changed in the window leading up to the incident. |
Limits
Range analyses consume analysis credits based on the number of commits in the range. A range covering 5 commits uses 5 credits. See Plans and Pricing for monthly limits by plan.
Next steps
- Commit Analysis -- Analyze a single commit in detail.
- Automatic Analysis -- Set up automatic analysis on every push to a repository.