Venkatesh demonstrated a strong grasp of CI/CD system design at a staff+ level. He showcased an ability to deconstruct the problem and apply scalable architectural patterns effectively, with solid articulation of trade-offs and best practices across core infrastructure components.
Areas of strength included:
- Excellent identification of functional and non-functional requirements, with numeric metrics.
- Clear separation of responsibilities across components (e.g., webhook ingestion, orchestrator, parser, job runners).
- Good assumptions on triggering logic (e.g., master branch commit), and clean explanation of webhook-to-workflow lifecycle.
- Strong architectural principles: async queuing for decoupling, modular parser for DAG construction, autoscaling job runners, etc.
- Thoughtful use of idempotency keys, mTLS for secure inter-service communication, and classification of storage layers by intent (S3, Redis, etc.).
- Creative dual-mode logging via pub/sub and websocket forwarding.
- Ability to dive into failure handling strategies, retries with cutoff, and handling of secrets and credentials.
Areas for improvement:
- Clarify API and entity relationships between jobs and runs; include timestamps and worker_id for better fairness and tracking.
- Revisit log streaming mechanism — consider Server-Sent Events (SSE) as a more suitable option over websockets in some cases.
- Make the distinction between scheduling and execution layers clearer in both explanation and diagram.
- Consider batching strategies (micro-batching) in log collection and transmission for performance.
- Be more explicit on the lifecycle and timing of secret setup (pre-scheduled or just-in-time).
- Add nuance around retry handling — such as changing worker assignment and orchestrator feedback loops.
- Address corner cases: task timeouts, cancellations, and downstream impact of failure or interruption.
Suggestion:
- Incorporate a design for timeout and cancellation handling — consider how downstream tasks should respond to cancelled predecessors.
