Docker with REST API - How to push REST POSTed data, as a file, to host network

Expected behavior- The REST API receives data via a POST request and writes the data to a local file. I would like to copy the file in some manner to a network share or FTP to a host FTP address.

This will be deployed in Azure using API Management.

Actual behavior

The REST API can receive the data, but I am not sure ‘how’ to move it outside of container.

Additional Information

I am also questioning if containerization seems appropriate for this task. If REST API can be installed in Azure as just a Web App, then network connection might be easier.

Steps to reproduce the behavior