One of the systems on my home network can be switched on/off using IPMI. Since Home Assistant is running 24/7, it would be useful to be able to power toggle this system straight from Home Assistant.

There is currently no add-on or integration that can perform this task. In the meantime, the following hack provides a workaround.

configuration.yaml

shell_command:
  ipmi_install_and_trigger: "which ipmitool >/dev/null 2>&1 || (apk update && apk add ipmitool); ipmitool -H <INTERNAL_IP_ADDRESS> -U admin -P <PASSWORD> chassis power on"

Lovelace

[...]
    cards:
[...]
      - name: 'install ipmitool and trigger <SERVER_NAME>'
        type: button
        tap_action:
          action: call-service
          service: shell_command.ipmi_install_and_trigger
        show_icon: true
        show_name: true

You can install this lovelace card in your existing dashboard by using the raw configuration editor and pasting the above in the respective section.