How to emulate persistent file-system on cloudfoundry/similar PaaS?

Question

In Cloudfoundry, there is no persistent file-system storage in the app containers. The standard suggestion is to use DB, but I have a specific scenario where write to persistent file is needed. I use a 3rd party app that requires storing config data on file. I can select the file path but I cannot override the persistent file storage requirement.

Is there any library that abstracts filesystem visible to Java and actually stores files on Amazon S3?

It is only one single file that builds up as we go along. The file size is about 1 MB but could reach a few MBs.

Answer 1

The application design documentation from cloud foundry recommends not writing to the local file system:

• http://docs.cloudfoundry.org/devguide/deploy-apps/prepare-to-deploy.html#filesystem

This is to be compliant with what is called a 12 factor application where one uses backing services to access items like storage systems and run processes that don't rely on shared storage.

Unfortunately there does not appear to be a file system service for Cloud Foundry, although it's been discussed:

• https://groups.google.com/a/cloudfoundry.org/forum/#!topic/vcap-dev/Kj08I2H7HHc

Such a service will eventually appear in order to support applications like Drupal, in spite of recommendations to use more efficient mechanisms like S3 to store files.