When running manually in a centos7 container, the error message is this:

Error: Could not start Service[webhook-go]: Execution of '/sbin/service webhook-go start' returned 1: Redirecting to /bin/systemctl start webhook-go.service
Failed to get D-Bus connection: Operation not permitted
Error: /Stage[main]/R10k::Webhook::Service/Service[webhook-go]/ensure: change from 'stopped' to 'running' failed: Could not start Service[webhook-go]: Execution of '/sbin/service webhook-go start' returned 1: Redirecting to /bin/systemctl start webhook-go.service
Failed to get D-Bus connection: Operation not permitted

Seems to be related to systemd, Google says. OTOH, when I run the acceptance test for https://github.com/voxpupuli/puppet-rsyslog on centos7, the test for the service works. I am unable to spot any differences in the test setup. Probably I am looking into the wrong places.