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I'm using an RPi 2 model B for this project. Here are my notes.

Pi <-> RPi <-> Raspberry Pi

Cerealbot Code


Curl is great for testing around with both Octoprint and RedQueen's api, but I've switched the shell scripts to use resty for ease of maintenance.

Curl Examples
To RedQueen:
curl --data "{\"message\":\"${MSG}\", \"channel\":\"##rqtest\", \"isaction\":false, \"key\":\"${APIKEY}\"}" https://crump.space/rq/relay -H "Content-Type:application/json"
To Octoprint:
curl -H "X-Api-Key:$OCTO_API_KEY" http://bns-daedalus.256.makerslocal.org/api/printer -o /tmp/printr_status.json



I'm just using Rasbian from the foundation's download page. I find Debian derivatives to be comfortable for projects such as this. You're welcome to use whatever distro you like.

I strongly recommend you follow some official guide for installing the OS if you're at all uncertain. The notes here are sparse and meant to make it faster for me to recover from a broken system.

Get the archive, extract the file. Should be along the lines of '2015-05-05-rasbian-wheezy.img'.

Flash it to the SD card: 'sudo dd if=2015...img of=/dev/sdX bs=4M'.

Configure things with the raspi tool that loads on first boot, then install your favorite packages. Mine are:

htop vim emacs byobu tmux build-essential bash-completion haproxy authbind

Set the time/zone


By default, Rasbian has an ntp daemon running, but you may still need to select a timezone. Use tzselect to set the timezone, then echo the returned line into .profile.

for me, this means:

echo "TZ='America/Chicago'; export TZ" >> ~/.profile

Setup SSH

I really recommend setting up SSH keys. There are many good guides for this elsewhere.

Setup Git

There's really no need to do this, but I like having git handle passwords for me.


git config --global credential.helper 'cache --timeout=3600'

Setup Byobu

F1 allows you to set "log into byobu" to save some time while logging in.

'C-a a' will send C-a to /usr/bin/screen, so you can use screen within byobu to debug serial connections.

Sometimes BYOBU will make life miserable. To disable it:

  • byobu-disable
  • ssh -t IP bash
  • export LC_BYOBU=0

Recover SD Filesystem

Hypothetically, in a strictly theoretical sense, with no basis whatsoever to the real world and real people:

Say someone at your hackerspace is horsing around and trips the breaker that your Pi is powered from. Well if you're lucky, then you just walk over and reboot the sucker. Sometimes that doesn't work though, and the computer's little SD card has become corrupt. Rather than break out the backup that you totally have, let's try a quick recovery first.

First, remove the SD card and insert it into your computer. Make sure it is unmounted.

Test recovery:

sudo dd if=/dev/sdX2 of=pi_bkup.img status=progress
cp pi_bkup.img pi_bkup_recv.img
sudo e2fsck -fy pi_bkup_recv.img

You may have to run that last command twice, idk why. If the program successfully recovers the test image, you have two options:

  • Flash this cured image file back to the partition it came from
  • Try to directly recover the SD card, since you know it has a chance of working.

The second option is faster:

sudo e2fsck -fyt /dev/sdX2

Reference thread

Good luck!

Raspberry Pi PWN Count: 3 (Why the hell does the Raspberry Pi foundation ship a board capable of ejecting its own hard drive?!)

Migrate to Jessie

Ugh, next time we use Archlinux-Arm, OK?

Update just the mirror source in /etc/sources.list from wheezy to jessie.

# apt-get update
# apt-get upgrade
# apt-get dist-upgrade
# rpi-update

Set graphical/tty login

Jessie won't be set to tty login by the raspi-config tool. You have to do it manually:

# systemctl set-default multi-user.target # No Graphics
## OR ##
# systemctl set-default graphical.target # GUI



There are good guides elsewhere for installing Octoprint. I really don't see a need for repeating the instructions.

  • Install Octoprint
  • Have it start on boot
  • Configure your account
  • Generate an API key

Authbind to Port 80

If your network supports it, go ahead and use HAProxy. Ours didn't work initially, so I gave up and instead used Authbind.


sudo apt-get install authbind
sudo touch /etc/authbind/byport/80
sudo chown pi /etc/authbind/byport/80
sudo chmod 500 /etc/authbind/byport/80

Adjust a few lines in /etc/default/octoprint to match:


In /etc/init.d/octoprint you need to add a line for authbind in the variable declaration area:

DESC="Octoprint Daemon"

In the same file, you then need to find the line which starts octoprint and insert authbind:

start-stop-daemon --start --background --quiet --pidfile $PIDFILE --make-pidfile \
       --exec $DAEMON --chuid $OCTOPRINT_USER --user $OCTOPRINT_USER --umask $UMASK -- $DAEMON_ARGS


start-stop-daemon --start --background --quiet --pidfile $PIDFILE --make-pidfile \


This is the current go-to tool for webcam streaming with octoprint. If you have a webcam set up, then you can totes ignore this section. It's also worth browsing around to see if you find a process you like better than mine.

First, you may want to collect some information on your webcam:

To list available formats:

v4l2-ctl --list-formats


v4l2-ctl -d /dev/videoX --list-formats-ext | less


There are general instructions for installing mjpg-streamer on octoprint's wiki. I've detailed some changes to incorporate a different version and setup a daemon.

mjpg-streamer-experimental is by far my favorite solution for webcam streaming from the RPi. A recent update brought immense relief for CPU overhead.

Follow the Apt/Pacman directions below, and then continue from here.

Git the project:

git clone https://github.com/jacksonliam/mjpg-streamer.git
cd mjpg-streamer/mjpg-streamer-experimental/
make clean
make all

The base command to run mjpg-streamer. Don't worry about this, its handled by an init.d script.

mjpg_streamer -b -i "./input_uvc.so -d /dev/video0 -n -f 5 -r 1280x720" -o "./output_http.so -p 8080 -w ./www"

Previously I've used the -y flag for compatibility, which totally crushed the little CPU, but the most recent build of mjpg-streamer-experimental appears to work quite well with my Logitech webcam using the default MJPG codec.


Install some dependancies:

sudo apt-get install libjpeg62-dev cmake subversion imagemagick libav-tools


I don't remember what prereqs are needed..

Systemd Init Script

If you're using mjpg-streamer-experimental, then you can make the start.sh file like so. ~/mjpg-streamer/mjpg-streamer-experimental/start.sh:


#                                                                              #
#      MJPG-streamer allows to stream JPG frames from an input-plugin          #
#      to several output plugins                                               #
#                                                                              #
#      Copyright (C) 2007 Tom St<C3><B6>veken                                         #
#                                                                              #
# This program is free software; you can redistribute it and/or modify         #
# it under the terms of the GNU General Public License as published by         #
# the Free Software Foundation; version 2 of the License.                      #
#                                                                              #
# This program is distributed in the hope that it will be useful,              #
# but WITHOUT ANY WARRANTY; without even the implied warranty of               #
# GNU General Public License for more details.                                 #
#                                                                              #
# You should have received a copy of the GNU General Public License            #
# along with this program; if not, write to the Free Software                  #
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA    #
#                                                                              #

export LD_LIBRARY_PATH=`dirname $0`
DIR=`dirname $0`
$DIR/mjpg_streamer -i "input_uvc.so -d /dev/video0 -n -f 5 -r 1280x720" -o "output_http.so -p 8080 -w $DIR/www"

Create /etc/systemd/system/mjpg-streamer.service:

Description=mjpg-streamer daemon



SysV Init Script

Go to foosel's mjpg init page and copy-pasta the two files into /etc/init.d/mjpg-streamer and /etc/default/mjpg-streamer respectively.

Don't forget to edit /etc/default/mjpg-streamer to your liking, and make /etc/init.d/mjpg-streamer executable!

sudo chmod +x /etc/init.d/mjpg-streamer
sudo update-rc.d mjpg-streamer defaults

If you have troubles, make sure to sudo update-rc.d mjpg-streamer remove and then reboot each time while working on it manually.

I've modified the init scripts while facerolling to try and get this junk working.



# Provides:          mjpg-streamer
# Required-Start:    $local_fs networking
# Required-Stop:
# Should-Start:
# Should-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: mjpg-streamer daemon
# Description:       Starts the mjpg-streamer daemon with the user specified in
#                    /etc/default/mjpg-streamer.
# Author: Sami Olmari
DESC="mjpg-streamer Daemon"
# Read configuration variable file if it is present
[ -r /etc/default/$PKGNAME ] && . /etc/default/$PKGNAME
# Exit if the mjpg-streamer is not installed
[ -x "$DAEMON_HOME/$DAEMON" ] || exit 0
# Load the VERBOSE setting and other rcS variables
[ -f /etc/default/rcS ] && . /etc/default/rcS
# Define LSB log_* functions.
# Depend on lsb-base (>= 3.0-6) to ensure that this file is present.
. /lib/lsb/init-functions
if [ -z "$RUN_AT_STARTUP" -o "$RUN_AT_STARTUP" != "YES" ]
   log_warning_msg "Not starting $PKGNAME, edit /etc/default/$PKGNAME to start it."
   exit 0
    log_warning_msg "Not starting $PKGNAME, MJPG_STREAMER_USER not set in /etc/default/$PKGNAME."
    exit 0
# Function to verify if a pid is alive
   pid=`cat $1` > /dev/null 2>&1
   kill -0 $pid > /dev/null 2>&1
   return $?
# Function that starts the daemon/service
   # Return
   #   0 if daemon has been started
   #   1 if daemon was already running
   #   2 if daemon could not be started
   is_alive $PIDFILE
   if [ $RETVAL != 0 ]; then
       start-stop-daemon --start --pidfile $PIDFILE --make-pidfile --chuid $MJPG_STREAMER_USER --user $MJPG_STREAMER_USER --umask $UMASK \
	echo "\nRetval: $RETVAL"
# Function that stops the daemon/service
   # Return
   #   0 if daemon has been stopped
   #   1 if daemon was already stopped
   #   2 if daemon could not be stopped
   #   other if a failure occurred
   start-stop-daemon --stop --quiet --retry=TERM/30/KILL/5 --user $MJPG_STREAMER_USER --pidfile $PIDFILE
   [ "$RETVAL" = "2" ] && return 2
   rm -f $PIDFILE
   [ "$RETVAL" = "0"  ] && return 0 || return 1
case "$1" in
   [ "$VERBOSE" != no ] && log_daemon_msg "Starting $DESC" "$NAME"
   case "$?" in
      0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
      2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
   [ "$VERBOSE" != no ] && log_daemon_msg "Stopping $DESC" "$NAME"
   case "$?" in
      0|1) [ "$VERBOSE" != no ] && log_end_msg 0 ;;
      2) [ "$VERBOSE" != no ] && log_end_msg 1 ;;
   log_daemon_msg "Restarting $DESC" "$NAME"
   case "$?" in
      case "$?" in
         0) log_end_msg 0 ;;
         1) log_end_msg 1 ;; # Old process is still running
         *) log_end_msg 1 ;; # Failed to start
        # Failed to stop
      log_end_msg 1
   echo "Usage: $SCRIPTNAME {start|stop|restart}" >&2
   exit 3


# Configuration for /etc/init.d/mjpg-streamer
# The init.d script will only run if this variable non-empty.
# Where mjpg-streamer is installed, this is important!
# What arguments to pass to mjpg-streamer, here is few examples; You can change them by commenting one and
# uncommenting another:

#DAEMON_ARGS='-i "$DAEMON_HOME/input_uvc.so -r SXGA -f 15" -o "$DAEMON_HOME/output_http.so"'   # UVC-mode
#DAEMON_ARGS='-i "$DAEMON_HOME/input_uvc.so -y" -o "$DAEMON_HOME/output_http.so"'              # YUV-mode

# Umask of files mjpg-streamer generates, Change this to 000 if running mjpg-streamer as its own, separate user
# Should we run at startup?

Octoprint Protip

To use an http stream with octoprint, the URL has to be formatted correctly.

At first glance, I tried: cerealbox.256.makerslocal.org:8081, which didn't work.

Turns out Octoprint blindly appends a GET variable to the URL, which turns the above into: cerealbox.256.makerslocal.org:8081?2354jk345 which isn't a valid URL anymore.

So, you have to set up the webcam URL like: http://cerealbox.256.makerslocal.org:8081/

Here the trailing slash lands the GET variable. It took Hunter Fuller to figure all that out.

Streaming over RTMP

I don't want to give up mjpg-streamer, not when its working so well. But mjpg-streamer also can't export FLV, which is required for RTMP :(

Solution: Export mjpg-streamer normally, capture and convert, and re-export as FLV alongside. This does not work with Debian Wheeze, which is the standard for Rasbian! The version of avconv is too old, and will report errors. To get a newer version, I upgraded to Debian Jessie (which was awful). I now have avconv version:

avconv version 11.4-6:11.4-1~deb8u1+rpi1, Copyright (c) 2000-2014 the Libav developers
  built on Jun 16 2015 05:32:34 with gcc 4.9.2 (Raspbian 4.9.2-10)
avconv 11.4-6:11.4-1~deb8u1+rpi1
libavutil     54.  3. 0 / 54.  3. 0
libavcodec    56.  1. 0 / 56.  1. 0
libavformat   56.  1. 0 / 56.  1. 0
libavdevice   55.  0. 0 / 55.  0. 0
libavfilter    5.  0. 0 /  5.  0. 0
libavresample  2.  1. 0 /  2.  1. 0
libswscale     3.  0. 0 /  3.  0. 0

To run the conversion:

$ avconv -f mjpeg -i http://localhost:8080/?action=stream -f flv rtmp://friends-webserver.com/ctag

Node JS


From StackOverflow. I found it a requirement for node-gyp.

npm config set python python2.7


Don't do this. Building modules manually is just a waste of time once Node is installed.

http://elinux.org/Node.js_on_RPi - EEwiki page on downloading / building from source.

https://nodejs.org/dist/latest/ - Latest source release.


wget https://nodejs.org/dist/latest/node-v0.12.7.tar.gz
tar xzf node*.tar.gz
cd node-v0.12.7/
make -j 3
sudo make install


Well, if you're willing to break nearly every other part of this ecosystem in order to get node working, just upgrade the system to Jessie and then install Node/Mongodb/etc with apt-get.

Nearly the worst idea I've had this summer. Next time we use ArchlinuxArm.


uv4l is a promising tool to replace mjpg-streamer with faster performance on the RPi 2. Right now it just crashes my pi though.