I might not know what I'm talking about (our deployments don't do automatic migrations, for eg), but if I understand correctly, your problem is to synchronize migrations with deployments, is that accurate? Couldn't you use something like GitHub Actions to run migrations and then deploy to EB?
Yeah the goal is to get the steps to be: Build, Deploy & Run Migrations, Deploy & Rotate containers.
Github Actions is CI/CD and it can be used to kick off any deploy step and manage it, but it's not one to actually perform the migration. That would be like Github Actions actually running the webserver directly.
In this example Github Actions needs to kick off a `eb deploy`, which it can totally do (I personally use CircleCI) but `eb deploy` (elastic beanstalk in general) is not designed to run a short lived script on a single container AND wait for it to return.
You can run a short lived script no problem, but you have no idea if it was successful or not because once the container becomes 'healthy' the command completes.
What I'm really waiting for is the container.lastStatus:'STOPPED' and exitCode: 0. Can't do that on EB.
