Your company must upload historic data to Cloud Storage but on-prem security disallows external IP access to on-prem resources. After an initial upload, new data will be added daily from on-prem applications. What should they do?

Executing gsutil rsync from on-premises servers is the most suitable solution. gsutil is a command-line tool that can be installed on-premises and used to transfer data to Cloud Storage. This method works well for both initial bulk uploads and subsequent incremental updates, as rsync efficiently handles only changed or new files. It also addresses the security constraint by not requiring external IP access to on-prem resources, as the connection is initiated from on-prem to Google Cloud. Using Dataflow or Dataproc for simple file transfer is overkill and more complex than necessary; these services are designed for data processing and transformation, not basic ingress. Installing an FTP server on Compute Engine would introduce unnecessary infrastructure management and potential security vulnerabilities, and still requires a mechanism to move data from the FTP server to Cloud Storage.