Learn the vocabulary of switching live traffic between two identical production environments.
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At standup, a dev mentions running two identical production environments and switching all live traffic from the old one to the new one instantly once it's verified. What is this deployment strategy called?
Blue-green deployment runs two identical production environments, one currently live and one newly deployed, and switches all live traffic instantly from the old environment to the new one once it's been verified. This makes a rollback fast and simple, since traffic can be switched back to the still-running previous environment if an issue is discovered. It's a distinct strategy from a gradual traffic shift, which moves users over incrementally rather than all at once.
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During a design review, the team wants to verify the newly deployed environment works correctly using real production-like checks before switching any live traffic to it. Which capability supports this?
Pre-switch smoke testing runs real, production-like checks against the newly deployed environment before any live traffic is switched to it, catching an obvious issue while the previous environment is still safely handling all real traffic. Switching traffic immediately with no verification risks exposing every user to a broken new environment at once. This verification step is what makes the instant traffic switch of blue-green deployment a reasonably safe strategy rather than a risky gamble.
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In a code review, a dev notices the previous environment is deliberately kept running for a period after the switch, rather than being torn down immediately. What does this represent?
Retaining the prior environment for a fast rollback window keeps the previously live environment running and ready, so traffic can be switched back to it quickly if an issue is discovered shortly after the new environment goes live. Tearing it down immediately removes that safety net, forcing a much slower rebuild from scratch if a rollback becomes necessary. This retention period is a key part of what makes blue-green deployment's rollback so fast compared to other deployment strategies.
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An incident report shows a blue-green switch happened successfully, but a database schema change wasn't backward-compatible, breaking the still-running previous environment during the retained rollback window. What practice would prevent this?
Ensuring a database schema change stays backward-compatible with the previous environment throughout the rollback window keeps that previous environment actually usable as a fallback if needed. A schema change that immediately breaks compatibility undermines the whole point of retaining the previous environment for a fast rollback. This compatibility discipline is a well-known, important nuance of blue-green deployment whenever a release includes a database change.
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During a PR review, a teammate asks why the team uses blue-green deployment instead of deploying the new version directly on top of the existing production environment. What is the reasoning?
Deploying directly on top of the existing production environment overwrites the only version currently running, making a rollback slow and effortful if something goes wrong. Blue-green deployment keeps the previous environment intact and ready, enabling a near-instant traffic switch back if an issue surfaces. The tradeoff is the added infrastructure cost of running two full environments simultaneously, even if only briefly.