I'm currently running a Dockerized NodeJS application that's using Postgres. The Postgres database url is coming as an environment variable, as set by Heroku. While this works great inside my container, I'm wondering how I should go ahead about running database migrations.
At which stage should I be doing this? I suppose I can't do this as part of my docker build process, as this happens outside of the Heroku environment.
What's the correct process for something like this?