Design Container Registry

Hard45 min
1 / 30
understanding9 min read

Problem Statement: Enterprise Container Registry

How Problem Statement: Enterprise Container Registry (understanding) informs Container Registry architecture and interviewer depth.

Problem Statement: Enterprise Container Registry

Design a private OCI container registry that stores immutable images for thousands of microservices. Interviewers want separation of metadata plane (manifests, tags, ACLs, scan status) from blob plane (content-addressable layers in object storage). Anchor outcomes: p99 pull start < 800ms for warm layers in-region, 99.99% registry API availability, and policy-gated promotion so CVE-critical images never reach production clusters.

Interview Focus

  • Separate metadata plane from blob plane and state durability assumptions
  • Quantify deploy-wave pull fan-out before sizing API and CDN
  • Layer tenancy: RBAC, quotas, rate limits, and audit trails
  • Explain promotion gates: scan + signature before prod tag moves

How to open this one

The framing that signals depth on a container registry is separating the metadata plane (manifests, tags, ACLs, scan status) from the blob plane (content-addressable layers in object storage), because they scale and fail differently. Lead with content-addressing — identical layers stored once, pulls served warm from cache — and the failure story that matters: a CVE-critical image is requested for prod, and policy-gated promotion plus immutable digests stop it before it runs. That shows you understand a registry is a supply-chain control, not just storage.

Key Highlights

  • Pin prod deploys to immutable digests
  • Dedup layers in object storage by sha256
  • Async scan + policy before promotion
  • Replicate blobs per compute region
Staff+ signal
Link Problem Statement: Enterprise Container Registry to pull SLOs and supply-chain gates, not Docker Hub anecdotes alone.
Avoid
Treating registry as dumb storage without scanning, RBAC, replication, and GC discipline.

Section Rescue Kit

Buzzwords to use:

Content-addressable storageImmutable digest promotion

Safe statements:

  • "I'll anchor Problem Statement: Enterprise Container Registry to pull SLOs, tenant isolation, and measurable promotion gates."
  • "If pressed, I'll compare managed registries versus Harbor only after stating ops cost."
Design Container Registry - System Design | WinJob | WinJob