Spring Boot: migrations at startup, health checks and metrics
Migrations are written in development, but they have to run wherever the application runs: on a colleague's laptop, in CI, in staging, in production. The simplest way to get there is to let the application apply them itself, each time it starts, before anything else touches the database.
This article adds the Migrax starter to a Spring Boot application, follows what happens at startup, starts two instances at once, and looks at what Actuator shows: a health check and Prometheus metrics. At the end, the pipeline runs the migrations instead of the application.