For requests like /puppet/v3/file_metadata/acmedata/test_certificate/rsa-2048.key acme-chief is returning bad metadata making puppet to create a directory instead of a file. This has not been detected by our current test suite because /puppet/v3/file_content/acmedata/test_certificate/rsa-2048.key works as expected and the test covering /puppet/v3/file_metadata/acmedata/test_certificate/rsa-2048.key has an expected fail annotation.
This triggered https://wikitech.wikimedia.org/wiki/Incident_documentation/20190321-acmechief