The banner impression data is publicly hosted on an indexed directory on analytics.wikimedia.org.

Acceptance Criteria

• A file is only picked up/processed once.
• If a file is missing, the command writes an error output and exits with a non-zero status. Further processing is stopped.

Implementation Notes

• Guzzle should be used for testability and might even help parsing the files.
• Data download should happen in an interface for testability.
• Command should get a service that provides the filename of the next file to be processed (based on the file name conventions noted in the parent ticket).