Running Shopify’s Dashing on a Raspberry Pi

Dashing on a headless Raspberry Pi

Rough draft for reminder purposes

Micronext wireless USB adaptor, followed these instructions.

Installed gem, installed ruby, installed nodejs.

Followed the dashing homepage instructions to install dashing.

Added init.d script to auto start dashing in production mode on port 5000.

Followed these instructions to autostart Chrome in kiosk mode on the pi. What I did differently was to use Hexxeh’s Chrome instead of chromium-browser as chromium-browser hogged memory and would crash badly. I also made the custom-x-start script dependant on the dashing startup script to give dashing a chance to start before Chrome tried to load it. Dashing takes about 30 seconds to get started.

#!/bin/bash

### BEGIN INIT INFO
# Provides:        dasher_start
# Required-Start:  $network $syslog
# Required-Stop:
# Default-Start:   2 3 4 5
# Default-Stop:
# Short-Description: Starts up the dasher server
### END INIT INFO

set -e

# Feel free to change any of the following variables for your app:
TIMEOUT=${TIMEOUT-60}
APP_ROOT=/home/pi/dashboard/example_dashboard
PID=$APP_ROOT/tmp/pids/thin.5000.pid
CMD="cd $APP_ROOT; dashing start -s1 -d -p 5000 -e production -P $PID "
AS_USER=pi
set -u

OLD_PIN="$PID.oldbin"

sig () {
  test -s "$PID" && kill -$1 `cat $PID`
}

oldsig () {
  test -s $OLD_PIN && kill -$1 `cat $OLD_PIN`
}

run () {
  if [ "$(id -un)" = "$AS_USER" ]; then
    eval $1
  else
    su -c "$1" - $AS_USER
  fi
}

case "$1" in
    start)
      sig 0 && echo >&2 "Already running" && exit 0
      run "$CMD"
      ;;
    stop)
      sig QUIT && exit 0
      echo >&2 "Not running"
      ;;
    restart)
      sig HUP && echo reloaded OK && exit 0
      echo >&2 "Couldn't reload, starting '$CMD' instead"
      run "$CMD"
      ;;
    *) echo "usage: $0 start|stop|restart" >&2
       exit 1
       ;;
esac

As the startx script is running as root, I needed to add “–user-data-dir=/home/pi/chromium” to the path call as suggested by the error Chrome returns when trying to run as root.

Chromium-browser barely worked but Hexxeh’s Chrome uses about 50-55% memory (as reported by top) and the CPU seems to bounce around from 1-75%. Dashing’s sample page is rather JS heavy and over time eats up all available memory. It’s took about 4 hours before Chrome would render the sad face of a closed tab. As such I added a JS refresh to the top of dashing’s layout page so it reloads every 30 minutes. It makes for an unsightly white screen for 5 seconds every 30 minutes but it keeps the page from crashing.

How the hardware looks

The hardware as it stands