Using Multiple Buildpacks in Deis
To use multiple buildpacks with your Application Deployment on Deis Workflow, is pretty straight forward.
As heroku-buildpack-multi is already built into deis' slugbuilder, all you need to do is to create a .buildpacks file in your repository, insert your required buildpacks, commit and push away.
An example .buildpack could look like:
# .buildpacks
https://github.com/cloudfoundry/heroku-buildpack-ruby.git
https://github.com/gaumire/heroku-buildpack-mysql
Enjoy.