The guys over at Hypriot have been using Docker a lot. In this instance, they use Node.JS to drive a set of NeoPixels from the Pi. In the example, they use the Pi’s 5V power supply to provide the power directly (although this is not recommended) and an Adafruit level shifter to convert the PWM signal on pin 18 to 5V to provide the signal required for the NeoPixels. Read more here.