Download Integrity Checker for ASF Infra

This service runs as a Pipservice and verifies download artifacts using their accompanying chekcums and detached signatures, as per our release distribution policies ( outlined at https://infra.apache.org/release-distribution.html ).

When a mismatch is detected, projects (and infra) are notified of this via email.

TODO

  • check all directories and files for errors in sigs and hashes (not just some extensions)
  • where a project has multiple KEYS files, use the appropriate (closest) one only for checking