Blue-Green Deploy

ELI5 — The Vibe Check

Blue-green deploy runs two identical environments and swaps traffic between them — instant rollback, zero downtime, the adults' deploy strategy. Blue is production. Green is the new version. You deploy to green, test it, then flip the load balancer. All traffic moves to green instantly. If green blows up, you flip back to blue. The old version is just sitting there ready to save you. No scrambling, no redeploy.

Real Talk

In a blue-green deployment strategy, two identical production environments run simultaneously. Deployments target the inactive environment (green), which is validated before traffic switches via a load balancer or DNS update. The previously active environment (blue) stays live as an instant rollback target. This eliminates deployment downtime and reduces rollback time from minutes to seconds. The cost is running double the infrastructure during transitions — typically brief enough to be acceptable.

When You'll Hear This

"We do blue-green deploys — rollback is just flipping the load balancer back." / "Blue-green is table stakes for anything with an SLA. Downtime deploys are a startup thing."