Comment 1 for bug 2051569

This is the reason why the port was open: the apache2 unit (which serves port 8991) was down:

Jan 28 01:35:35 juju-f7587a-5-lxd-3 systemd[1]: Stopping The Apache HTTP Server...
Jan 28 01:35:35 juju-f7587a-5-lxd-3 apachectl[83060]: AH00526: Syntax error on line 33 of /etc/apache2/sites-enabled/openstack_https_frontend.conf:
Jan 28 01:35:35 juju-f7587a-5-lxd-3 apachectl[83060]: SSLCertificateFile: file '/etc/apache2/ssl/designate/cert_designate.silo5.lab1.solutionsqa' does not exist or is empty
Jan 28 01:35:35 juju-f7587a-5-lxd-3 apachectl[83058]: Action 'graceful-stop' failed.
Jan 28 01:35:35 juju-f7587a-5-lxd-3 apachectl[83058]: The Apache error log may have more information.
Jan 28 01:35:35 juju-f7587a-5-lxd-3 systemd[1]: apache2.service: Control process exited, code=exited, status=1/FAILURE
Jan 28 01:35:35 juju-f7587a-5-lxd-3 systemd[1]: apache2.service: Failed with result 'exit-code'.
Jan 28 01:35:35 juju-f7587a-5-lxd-3 systemd[1]: Stopped The Apache HTTP Server.
Jan 28 01:35:35 juju-f7587a-5-lxd-3 systemd[1]: Starting The Apache HTTP Server...
Jan 28 01:35:35 juju-f7587a-5-lxd-3 apachectl[83067]: AH00526: Syntax error on line 33 of /etc/apache2/sites-enabled/openstack_https_frontend.conf:
Jan 28 01:35:35 juju-f7587a-5-lxd-3 apachectl[83067]: SSLCertificateFile: file '/etc/apache2/ssl/designate/cert_designate.silo5.lab1.solutionsqa' does not exist or is empty
Jan 28 01:35:35 juju-f7587a-5-lxd-3 apachectl[83064]: Action 'start' failed.
Jan 28 01:35:35 juju-f7587a-5-lxd-3 apachectl[83064]: The Apache error log may have more information.
Jan 28 01:35:35 juju-f7587a-5-lxd-3 systemd[1]: apache2.service: Control process exited, code=exited, status=1/FAILURE
Jan 28 01:35:35 juju-f7587a-5-lxd-3 systemd[1]: apache2.service: Failed with result 'exit-code'.
Jan 28 01:35:35 juju-f7587a-5-lxd-3 systemd[1]: Failed to start The Apache HTTP Server.