Design multi-tenant CI/CD platform

Q: Design multi-tenant CI/CD platform

This question evaluates a candidate's ability to design a cloud-native, multi-tenant CI/CD platform, assessing competencies in distributed systems architecture, security and tenant isolation, pipeline execution semantics, scalability, cost attribution, and observability within the System Design domain.

Q: How do I approach System Design interview questions?

System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master system design interviews.

Q: What difficulty level is this interview question?

This is a hard difficulty System Design question, commonly asked during Technical Screen rounds at OpenAI.

Q: What role is this question designed for?

This question is commonly asked for Software Engineer candidates at OpenAI during technical interviews.

Question

System Design: Multi‑Tenant CI/CD Platform

Context

Design a cloud-native, multi-tenant CI/CD platform that integrates with popular source control providers. Assume you can use managed cloud services and/or Kubernetes. Support Linux runners by default, with an option to extend to Windows/macOS via dedicated pools.

Requirements

1) Architecture and Key Components

Specify a high-level architecture and the responsibilities/choices for:

Source control integration (OAuth/apps, webhooks, Git mirroring)
Pipeline scheduler/executor
Build runners/agents
Artifact and image storage
Secret management
Caching (source, dependency, build cache)
Queue/stream for scheduling
Metadata database
External and internal APIs (REST/gRPC/webhooks), including eventing

2) Multi-Tenancy and Security

Explain how you ensure:

Tenant isolation (namespaces, per-tenant runner groups, network and data isolation)
RBAC with role scopes and secret scoping
Rate limiting and quotas (API, concurrency, storage)
Protection from noisy neighbors (fair scheduling, resource limits)

3) Pipeline Execution Semantics

Describe:

DAG model, conditionals, matrices
Retries/backoff, timeouts, cancellations
Idempotency and deduplication

4) Scaling

Cover:

Autoscaling runners/agents
Horizontal scaling and sharding of the control plane and scheduler
Multi-region considerations (if any)

5) Cost Tracking and Billing per Tenant

Describe meters, aggregation, and how you attribute cost by tenant/project.

6) Observability and Compliance

Include:

Logs, metrics, traces, correlation IDs
Audit logging and retention
Disaster recovery strategy
Zero-downtime deployments and backward-compatible migrations

7) Trade-offs

Compare:

Shared vs dedicated runner pools
Managed vs self-hosted agents

8) Deployment Plan

Outline how you would roll out the system in phases, including validation and guardrails.