Recently I made a S3 demo application which you can deploy in Nutanix Karbon using Calm, and it has web interface from where you can upload files directly to Nutanix S3 bucket. It's made using node.js platform. I tried to make everything streamlined using Nutanix Calm, so I made Docker Host, Docker Registry blueprints (Docker registry seeded blueprint, doesn't work because it doesn't save the the registry's password properly), docker image build Runbook pipeline and blueprint for deploying S3 demo application to Karbon cluster.
Whole project can be found here and includes full step-by-step instructions guide - https://github.com/vildek/s3demo
Hope this helps somebody understanding the platform better! Cheers.