Comparison
Blue-green deploymentvsRolling deployment
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 deployment
instances are replaced a few at a time, so both versions serve traffic simultaneously for several minutes.
Replacing instances incrementally, controlled by how many extra may exist and how many may be missing at once. It is the default because it needs no spare environment and no traffic switch, and its defining consequence is version coexistence: your database schema, your caches and your APIs must tolerate both versions at once. Rollback is slow, because undoing it is another roll.
Full entry →