Goal: 

• As a developer, I need the eventlet migration work not to break service units put in place by prior installations of Ironic services. The previous service launcher code had support for signal handling in relation to systemd, where as the newer threaded runner does *not. This is a regression of behavior and should be addressed.{}{*}

*Context*

*This item is much more about "keep the upstream UX" happy, in that in the name of speed upstream contirbutors chose to merge an eventlet alternative backend for oslo.service which lacks support for systemd signals. Moving this item along will keep upstream bifrost and Openshift Metal team in a happier place. For additional context, please see: https://review.opendev.org/c/openstack/oslo.service/+/945720* 

Acceptance Criteria:

• Merged fix into oslo.service for comparability.