This bug is a clone of https://bugzilla.redhat.com/show_bug.cgi?id=1633900

Description of problem:

We want to disable panko service since we don't use OpenStack with CloudForms.
We deployed overcloud according with following solutions.

  How to disable Panko service in RHOSP13.
  https://access.redhat.com/solutions/3527641

After that, we noticed ceilometer_agent_notification container didn't start correctly.

  # docker ps | grep ceilometer_agent_notification
  e9914c55235a        192.168.14.1:5000/rhosp13/openstack-ceilometer-notification:13.0-54     "kolla_start"            30 hours ago        Restarting (1) About a minute ago                       ceilometer_agent_notification

  # docker inspect ceilometer_agent_notification | grep Status
            "Status": "restarting",
                "Status": "starting",

  # docker logs  ceilometer_agent_notification
  + sudo -E kolla_set_configs
  INFO:__main__:Loading config file at /var/lib/kolla/config_files/config.json
  INFO:__main__:Validating config file
  INFO:__main__:Kolla config strategy set to: COPY_ALWAYS
  INFO:__main__:Copying service configuration files
  INFO:__main__:Deleting /etc/ceilometer/ceilometer.conf
  INFO:__main__:Copying /var/lib/kolla/config_files/src/etc/ceilometer/ceilometer.conf to /etc/ceilometer/ceilometer.conf
  INFO:__main__:Deleting /etc/ceilometer/event_pipeline.yaml
  INFO:__main__:Copying /var/lib/kolla/config_files/src/etc/ceilometer/event_pipeline.yaml to /etc/ceilometer/event_pipeline.yaml
  INFO:__main__:Deleting /etc/ceilometer/polling.yaml.org
  INFO:__main__:Copying /var/lib/kolla/config_files/src/etc/ceilometer/polling.yaml.org to /etc/ceilometer/polling.yaml.org
  INFO:__main__:Deleting /etc/ceilometer/polling.yaml
  INFO:__main__:Copying /var/lib/kolla/config_files/src/etc/ceilometer/polling.yaml to /etc/ceilometer/polling.yaml
  ERROR:__main__:MissingRequiredSource: /var/lib/kolla/config_files/src-panko/* file is not found

  # docker inspect ceilometer_agent_notification | grep panko
                "/var/lib/config-data/puppet-generated/panko/:/var/lib/kolla/config_files/src-panko:ro",
                "Source": "/var/lib/config-data/puppet-generated/panko",
                "Destination": "/var/lib/kolla/config_files/src-panko",

From the result of above docker commands, it seems that ceilometer_agent_notification container cannot start 
 if /var/lib/config-data/puppet-generated/panko/ is empty.

For testing purpose, we locate dummy file under /var/lib/config-data/puppet-generated/panko/, 
 the container successfully start.

  # touch  /var/lib/config-data/puppet-generated/panko/dummy
  # docker restart ceilometer_agent_notification
  # docker inspect ceilometer_agent_notification | grep Status
            "Status": "running",
                "Status": "healthy",
  # docker logs ceilometer_agent_notification | grep -3 dummy
  INFO:__main__:Copying /var/lib/kolla/config_files/src/etc/ceilometer/polling.yaml.org to /etc/ceilometer/polling.yaml.org
  INFO:__main__:Deleting /etc/ceilometer/polling.yaml
  INFO:__main__:Copying /var/lib/kolla/config_files/src/etc/ceilometer/polling.yaml to /etc/ceilometer/polling.yaml
  INFO:__main__:Copying /var/lib/kolla/config_files/src-panko/dummy to /dummy
  INFO:__main__:Writing out command to execute
  ++ cat /run_command
  + CMD='/usr/bin/ceilometer-agent-notification --logfile /var/log/ceilometer/agent-notification.log'


Version-Release number of selected component (if applicable):

 openstack-ceilometer-notification 13.0-54
 openstack-tripleo-heat-templates-8.0.4-20.el7ost.noarch

How reproducible:

Always

Steps to Reproduce:

Deploy overcloud with ceilometer without panko.
The procedure is described at following solutions.

  How to disable Panko service in RHOSP13.
  https://access.redhat.com/solutions/3527641

Actual results:

ceilometer_agent_notification is stuck at restarting

Expected results:

ceilometer_agent_notification starts successfully