Add as a first buildpack in the chain. Make sure you have yarn socket and yarn migrate command in package.json.

How to use:

1. heroku buildpacks:clear if necessary
2. heroku buildpacks:set https://github.com/timanovsky/subdir-heroku-buildpack
3. heroku buildpacks:add heroku/nodejs or whatever buildpack you need for your application
4. Deploy your project to Heroku.

How it works

The buildpack overwrites procfile with

web: yarn socket
release: yarn migrate