During the ops-infra work, random bugs found under Ubuntu16 (systemd) for st2mistral package:

• systemd unit files are missing for deb packages (!)
• After uninstalling st2mistral package:
  • mistral services remain in the running state
  • service mistral restart is executed and reports some status, even without a package installed
  • SysVInit scripts were not deleted
  • it's not possible to stop mistral-server normally, its state remains "active"

It looks like we didn't implemented systemd and never tested it properly under Ubuntu16 🤦‍♂️ 👊