Glossary · Phase 11 · Professional practice
Twelve-factor app
A set of practices for web services, such as reading configuration from environment variables so one image runs everywhere.
Try it now
Whichever you pick, rollback should be one action.
Learn it properly
Containers and deployment · Package an app as an image, configure it with the environment, and roll out safely. About 40 minutes.
Other terms from the same lesson
- blue-green deployment: Running a full new copy beside the old one, then switching all traffic at once, with instant rollback.
- canary release: Sending a small share of traffic to a new version first, to catch problems before everyone gets it.
- container image: A read-only package of an app with its system files and libraries, run as an isolated container.
- Dockerfile: A recipe of instructions that builds a container image, one layer per instruction.
- readiness check: Health checks a platform makes: liveness asks whether to restart the app; readiness asks whether to send it traffic.
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