Compare blue-green and canary deployment strategies
Reported in Mollie European engineering loops. Release engineering question focused on risk mitigation.
Interview scenario
Often asked in Mollie loops at European offices (London, Berlin, Amsterdam, Paris, Stockholm, Dublin, and remote EU). Prepare a clear spoken answer plus key trade-offs.
Model answer
Try answering aloud first
Cover trade-offs, structure, and a concrete example before revealing the baseline response.
How to frame this at Mollie: Connect your answer to measurable impact, clarity of thought, and trade-offs the team cares about. Below is a strong baseline response you can adapt with your own project examples.
Blue-green keeps two identical environments and switches traffic all at once, offering fast rollback but requiring higher infrastructure cost. It works well when full environment duplication is feasible.
Canary releases roll out gradually to a small traffic slice and increase over time based on health metrics. This lowers blast radius and reveals production issues early, but requires strong observability and traffic routing controls.
Interview-ready answers discuss when each model fits business risk, compliance requirements, and operational maturity.
Discussion
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