Issue with Moodle 3.1 about pylti

[dirkcgrunwald]

After a bit more time with PDB, I'm finding that commenting out line 170 in pylti/common.py as such:

    if lti_cert:                                                                                   
#        client.add_certificate(key=lti_cert, cert=lti_cert, domain='')                            
        log.debug("cert %s", lti_cert)             

removes the fault. Chasing this down isolates this to config.py, so simply removing config.py resolves the problem, but leaves me uncertain what the CONSUMER_KEY_PEM_FILE is for. Is this simply for having secrets in Heroku without having them visible?

[dirkcgrunwald]

And, after yet more digging, this appears to be an issue with using a LetsEncrypt certificate. When I switched the host to a Comodo certificate, everything worked fine. Presumably some package (httplib2?) installs a certificate list that somehow doesn't include LetsEncrypt.