How do I share files between multiple applications?

I have a multi-app project, and a mounted directory of files that I would like all applications to have access to. How do I accomplish this?

Project structure:

files/
application1/
   .platform.app.yaml
   ..
application2/
   .platform.app.yaml
   ..
..

In order to share writeable files across applications you need to use a network-storage service. That is, rather than the writeable directory living on each application container they both share a network mount to the same network drive.

See the documentation link above for specific instructions.