Comparison
Blue-green deploymentvsRolling update
Blue-green deployment
you stand up a complete second environment on the new version and switch all traffic to it at once.
Running two full environments and cutting traffic from the old to the new in one step, with the old kept warm for rollback. Rollback is a traffic switch, which is as fast as it gets. It doubles infrastructure for the duration and does not help with shared state: the database is still singular and still migrated.
Full entry →Rolling update
you replace the instances a few at a time, so for ten minutes half the fleet is on the old version and half on the new.
Replacing instances incrementally so capacity is maintained throughout. It is the default in every orchestrator and needs no extra infrastructure. It guarantees a period of mixed versions, which is why every change must be backward and forward compatible with the one before it.
Full entry →