Q: Your team has a monorepo with 10 services. The CI pipeline runs all 10 services' tests on every commit. How do you optimize this?
Use change detection to only build/test what changed:
#CI/CD #GitOps & Deployment Strategies #L2 #DevOps #Automation #Pipelines
🎙️ Candidate Opening & Architectural Context
""When developers encounter this build or release bottleneck, my first goal is unblocking velocity safely. When addressing this question, I walk the interviewer through our production incident runbook: isolating the blast radius, checking diagnostic logs and metrics, and applying a safe fix.""
Advertisement
🛠️ Production Runbook & Step-by-Step Resolution
1️⃣
Production Solution & Architecture
Use change detection to only build/test what changed: In GitHub Actions: Then: if: steps.changes.outputs.service-a == 'true' — only run service-a jobs if service-a files changed. Tools: Nx (for Node.js monorepos), Bazel (Google's build system, very granular dependency tracking), Turborepo. Also: shared libraries are special — if a shared library changes, all services that depend on it must rebuild/retest. Your dependency graph must be accurate.
- uses: dorny/paths-filter@v2
id: changes
with:
filters: |
service-a:
- 'services/service-a/**'
service-b:
- 'services/service-b/**'
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: Use change detection to only build/test what changed:."
⚡ 60-Second Elevator Pitch Talking Points
- Immediate Triage: Use change detection to only build/test what changed:
- Run targeted verification commands before modifying configuration.
- Automate permanent guardrails (CI check, alerts, IaC policy) to prevent recurrence.
Advertisement