mock-systemd-bus

Systemd D-Bus API mocks for testing. When ran, this service will run systemd in a container and replace dangerous services with mock versions. At the moment this service will replace systemd-login Manager object under org.freedesktop.login1 to test interfacing with systemd units and system control.

This project has no goals of covering all risky systemd interfaces and features will be added as-needed.

Usage

docker-compose file

To use this service, setup a docker compose as below

version: '2.3'

services: 
  # The service setup
  mock-systemd:
    image: ghcr.io/balena-os/mock-systemd-bus
    # Necessary to run systemd in a container
    privileged: true
    volumes:
      - dbus:/shared/dbus
    environment:
      # Set this variable with the location of your shared bus socket
      # NOTE: do not use /run/dbus as this path is overwritten by systemd
      DBUS_SYSTEM_BUS_ADDRESS: unix:path=/shared/dbus/system_bus_socket
      # Optionally set-up any mock units you need. Service files for these
      # Will be created on service start
      MOCK_SYSTEMD_UNITS: openvpn.service dummy.service

volumes:
  dbus:
    driver_opts:
      # Use tmpfs to avoid files remaining between runs
      type: tmpfs
      device: tmpfs 

Creating and modifying system state

The service exposes an API on the same bus to manipulate system state.

Reset the system mock power state

dbus-send --system --print-reply \
		--dest=org.freedesktop.login1 \
		/org/freedesktop/login1 \
		"org.freedesktop.login1.Manager.MockReset

Get the system mock power state

dbus-send --system --print-reply \
		--dest=org.freedesktop.login1 \
		/org/freedesktop/login1 \
		org.freedesktop.DBus.Properties.Get string:org.freedesktop.login1.Manager "string:MockState"

Environment variables

Name	Description	Default Value
MOCK_SYSTEMD_UNITS	Space separated list of systemd unit names to create. The service will create these on the bus on start	'' (empty)