root@puppetmaster1001:/srv/private# cergen --generate --force -c swift_codfw --base-path /srv/private/modules/secret/secrets/certificates /srv/private/modules/secret/secrets/certificates/certificate.manifests.d/ 
2019-04-10 10:03:01,278 INFO     cergen                                   Generating certificates ['swift_codfw'] with force=True
2019-04-10 10:03:01,278 INFO     Certificate(swift_codfw)                 Generating all files, force=True...
2019-04-10 10:03:01,279 INFO     Certificate(swift_codfw)                 Generating certificate file
/usr/lib/python3/dist-packages/urllib3/connection.py:337: SubjectAltNameWarning: Certificate for puppetmaster1001.eqiad.wmnet has no `subjectAltName`, falling back to check for a `commonName` for now. This feature is being removed by major browsers and deprecated by RFC 2818. (See https://github.com/shazow/urllib3/issues/497 for details.)
  SubjectAltNameWarning
2019-04-10 10:03:01,340 WARNING  PuppetCA(puppetmaster1001.eqiad.wmnet_8140) CSR for swift_codfw to puppetmaster1001.eqiad.wmnet_8140 has already been submitted and signed. Not submitting again.
Traceback (most recent call last):
  File "/usr/bin/cergen", line 11, in <module>
    load_entry_point('cergen==0.2.3', 'console_scripts', 'cergen')()
  File "/usr/lib/python3/dist-packages/cergen/main.py", line 93, in main
    certificate.generate(force=args['--force'])
  File "/usr/lib/python3/dist-packages/cergen/certificate.py", line 291, in generate
    self.generate_crt(force=force)
  File "/usr/lib/python3/dist-packages/cergen/certificate.py", line 330, in generate_crt
    f.write(self.cert.public_bytes(serialization.Encoding.PEM))
AttributeError: 'NoneType' object has no attribute 'public_bytes'