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baseten·Software Engineer·Onsite - System Design / Architecture·Senior

SeniorPrefer not to say
Jun 2026Remote

Summary

System design round at Baseten focused entirely on building a CI/CD platform from scratch. Pretty intense scope for a single session, they wanted depth on basically every layer of the stack.

Questions Asked (4)

Q1

Design a CI/CD platform for engineering teams. Walk through pipeline definition, source control integration, build agents, artifact storage, deployment strategies, secret management, observability, and access control.

System DesignTechnical Trade-offs
Author's notes

This was a lot.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints (scale, team size, deployment frequency, security needs) to frame the design. Then walk through each component in a logical order, explaining trade-offs and how they integrate. Emphasize reliability, security, and developer experience throughout.

Pro tip: Anchor your design around the developer experience—show how your choices reduce friction (e.g., fast feedback loops, self-service pipelines) while maintaining security and reliability. This demonstrates product thinking and empathy for users.

1. Clarify Requirements and Constraints

Ask about scale (number of teams, repos, builds per day), deployment targets (cloud, on-prem, edge), compliance needs, and existing tooling. This ensures your design is tailored and shows you think before coding.

2. Design Pipeline Definition and Source Control Integration

Propose a declarative pipeline-as-code approach (e.g., YAML) stored alongside source. Explain how to integrate with Git providers via webhooks, handle branch strategies, and trigger builds on events.

3. Architect Build Agents and Artifact Storage

Discuss agent orchestration (e.g., Kubernetes-based, auto-scaling), isolation, and caching. Describe artifact storage (e.g., S3, Artifactory) with versioning, retention policies, and promotion across environments.

4. Define Deployment Strategies and Secret Management

Compare deployment strategies (blue-green, canary, rolling) and when to use each. Explain secret management using vaults (e.g., HashiCorp Vault, AWS Secrets Manager) with injection at runtime and audit logging.

5. Cover Observability and Access Control

Outline logging, metrics, and tracing for pipelines and deployments. Describe RBAC, SSO integration, and audit trails to secure access and meet compliance.

Key Points to Mention

  • Pipeline-as-code with versioning and reusable templates
  • Auto-scaling build agents with caching for speed
  • Artifact immutability and promotion across environments
  • Deployment strategies with automated rollback
  • Secret management with least privilege and rotation
  • Observability: pipeline metrics, deployment tracing, and alerting
  • Access control: RBAC, SSO, and audit logs

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q2

How would you handle queueing fairness across different teams sharing the same build infrastructure?

System DesignTechnical Trade-offs
Author's notes

Didn't see this angle coming mid-question.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the goals of fairness (e.g., preventing starvation, ensuring proportional access) and the constraints of the shared build infrastructure. Then propose a multi-tenant queueing system with per-team quotas, priority classes, and preemption, and discuss trade-offs like utilization vs. fairness and complexity vs. simplicity.

Pro tip: Emphasize that fairness is not just about equal shares but also about meeting SLAs and business priorities; suggest starting with a simple weighted fair queueing approach and iterating based on metrics like queue wait times per team.

1. Clarify requirements and constraints

Ask about the number of teams, their workloads, SLAs, and the current infrastructure's capabilities. Identify what 'fairness' means in this context (e.g., equal access, proportional to team size, priority-based).

2. Choose a queueing model

Propose a model such as weighted fair queueing, deficit round-robin, or hierarchical queues. Explain how it ensures fairness by allocating shares or priorities per team.

3. Design enforcement mechanisms

Describe how to implement quotas, rate limiting, and preemption. Consider using a central scheduler with per-team queues and dynamic weight adjustments based on demand.

4. Address trade-offs and edge cases

Discuss trade-offs: strict fairness may reduce overall utilization; preemption can cause thrashing; starvation risks if weights are static. Propose mitigations like aging or dynamic rebalancing.

5. Monitor and iterate

Suggest metrics (queue wait time, throughput per team, SLA violations) and a feedback loop to adjust weights or policies. Emphasize starting simple and evolving based on data.

Key Points to Mention

  • Weighted fair queueing or deficit round-robin for proportional sharing
  • Per-team quotas and rate limiting to prevent monopolization
  • Priority classes and preemption for urgent jobs
  • Trade-off between fairness and overall system utilization
  • Starvation prevention via aging or dynamic weight adjustment
  • Monitoring and observability to measure fairness and adjust policies

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q3

How do you guarantee tenant isolation in a shared CI/CD environment?

System DesignTechnical Trade-offs
Author's notes

Went straight to namespace-level container isolation and network policies.

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AI HintsAI Generated

Suggested Approach

Start by defining tenant isolation as a multi-layered problem: separate compute, network, and data planes for each tenant. Then walk through concrete mechanisms like namespacing, sandboxing, and per-tenant credentials, and discuss trade-offs between isolation strength and operational overhead.

Pro tip: Emphasize that perfect isolation is impossible; instead, aim for defense-in-depth and clearly communicate the residual risks and how you monitor for cross-tenant leaks.

1. Clarify requirements and threat model

Ask about the sensitivity of tenant data, compliance needs, and the cost of a breach to determine the required isolation level.

2. Isolate compute and execution

Use per-tenant runners, containers, or VMs with strict resource limits and no shared writable volumes to prevent cross-tenant interference.

3. Isolate network and secrets

Assign per-tenant network policies, service accounts, and secret stores so that one tenant cannot access another's credentials or internal services.

4. Isolate data and artifacts

Store build artifacts, caches, and logs in tenant-specific buckets or namespaces with encryption and access controls.

5. Monitor, audit, and test

Implement continuous auditing, anomaly detection, and regular penetration tests to verify isolation and catch drift.

Key Points to Mention

  • Use of Kubernetes namespaces, network policies, and pod security policies for compute isolation.
  • Per-tenant service accounts and short-lived credentials to avoid secret leakage.
  • Ephemeral runners that are destroyed after each job to prevent state persistence.
  • Encryption at rest and in transit for artifacts and logs, with tenant-specific keys.
  • Trade-offs: stronger isolation (e.g., VMs) increases cost and complexity; weaker isolation (e.g., shared runners) risks cross-tenant attacks.
  • Defense-in-depth: combine multiple layers and assume one layer may fail.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q4

What does a reproducible build actually require, and where does it typically break down?

System DesignTechnical Trade-offs
Author's notes

My favorite part of the whole interview.

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AI HintsAI Generated

Suggested Approach

Start by defining reproducible builds as producing bit-for-bit identical artifacts from the same source and environment, then walk through the key requirements: pinned dependencies, hermetic build environments, deterministic toolchains, and controlled inputs. Finally, discuss common breakdown points like timestamps, file ordering, network access, and toolchain nondeterminism, tying them to real-world trade-offs in CI/CD and deployment.

Pro tip: Emphasize that reproducibility is a spectrum, not a binary—many teams achieve 'practical reproducibility' by fixing the most impactful sources of nondeterminism first. Mention that at companies like Baseten, where model serving and infrastructure reliability matter, reproducible builds are critical for auditability and rollback safety.

1. Define Reproducible Builds

Clarify that a reproducible build yields identical outputs (e.g., binaries, container images) given the same source code, dependencies, and build environment, regardless of when or where it's built.

2. List Core Requirements

Cover the essential ingredients: pinned dependency versions (lockfiles), hermetic build environments (containers, sandboxes), deterministic toolchains (compilers, linkers), and controlled inputs (no network, fixed locale/timezone).

3. Identify Common Breakdown Points

Discuss typical sources of nondeterminism: embedded timestamps, filesystem ordering, parallel build race conditions, network fetches, and toolchain version drift.

4. Discuss Trade-offs and Mitigations

Explain how to balance reproducibility with build speed and developer experience—e.g., using caching, incremental builds, and reproducibility only for release artifacts.

5. Relate to Real-World Impact

Connect reproducibility to benefits like security (verifying binaries), debugging (consistent behavior), and compliance (audit trails), especially in ML infrastructure and deployment pipelines.

Key Points to Mention

  • Pinned dependencies and lockfiles (e.g., package-lock.json, go.sum, requirements.txt with hashes)
  • Hermetic build environments (Docker containers, Bazel sandboxing, Nix)
  • Deterministic toolchains and compilers (e.g., GCC's -frandom-seed, Rust's reproducible builds)
  • Common nondeterminism sources: timestamps, file paths, environment variables, parallel execution order
  • Trade-offs: full reproducibility can slow builds; often focus on release artifacts
  • Tools and practices: reproducible-builds.org, diffoscope, in-toto, SLSA framework

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.