intermediate · ~10 min

Migrate, then release

payments 2.0 is ready to ship, but it reads a refunds table that only exists once database migration 0042 has run. migrate.yaml is a Job that runs it.

Run the migration, wait for it to complete, and only then roll payments to ghcr.io/hackademy/payments:2.0. kubectl wait --for=condition=complete job/NAME blocks until a Job has finished, so nothing after it starts early.

kubectl wait

Blocks until an object meets a condition, then returns: --for=condition=complete for a Job, condition=available for a Deployment, condition=ready for pods. --timeout bounds the wait (30s by default) and makes it fail loudly. Scripts and release pipelines use it so one step never starts before the last one finished. Docs

Objectives

Migration 0042 completed
payments: 2 ready replicas on 2.0
No 2.0 pod started before the migration finished
Bonus: Wait with kubectl wait, not by watching

Best on a computer with a keyboard. It works on a phone, with shortcuts under the terminal.