Artifact Promotion (Build Once)
As a Mid-level engineer, explain Artifact Promotion (Build Once). What problem does it solve and how would you describe it in an interview?
Answers use simple, clear English.
Quick interview answer
At Mid-level depth: start with the problem, then mechanism, then a short example. Build a versioned image/package once in CI; promote the same digest through staging→prod.
Detailed answer
At Mid-level depth: start with the problem, then mechanism, then a short example. Build a versioned image/package once in CI; promote the same digest through staging→prod. Never rebuild for prod with different flags. Core: Build a versioned image/package once in CI; promote the same digest through staging→prod. Never rebuild for prod with different flags. Real-time example: CI pushes ghcr.io/app:sha-abc; staging and prod both pull sha-abc. Pros: What you tested is what you ship. Cons: Needs good registry + digest pinning. Common mistakes: latest tag in prod; rebuilding on deploy job. Best practices: Pin by digest; SBOM; sign images (cosign). Audience level: Mid-level.
Full explanation
Build a versioned image/package once in CI; promote the same digest through staging→prod. Never rebuild for prod with different flags.
Real example & use case
CI pushes ghcr.io/app:sha-abc; staging and prod both pull sha-abc.
Pros & cons
Pros: What you tested is what you ship. Cons: Needs good registry + digest pinning.
Common mistakes
latest tag in prod; rebuilding on deploy job.
Best practices
Pin by digest; SBOM; sign images (cosign).
Follow-up questions
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