sudo su and run the following

aptitude update

install all dependencies

aptitude -y install \
python-pip \
python2.7-dev \
libssl-dev \
libcurl4-openssl-dev \
python-numpy \
python-opencv \
libopencv-dev \
libjpeg-dev \
libpng-dev \
libx264-dev \
libass-dev \
libvpx1 \
libvpx-dev \
libwebp-dev \
webp \
gifsicle

install thumbor, will take a while

pip install thumbor

set default thumbor config

thumbor-config > /etc/thumbor.conf

adding a key

SECURITY_KEY = 'YZTlj1k5nFZA58U25eiJ5X3z9j8RhTg8'

create init file /etc/init/thumbor.conf

description "Thumbor image manipulation service"
author "Nicolas Danelon <nicolas@smarttly.com>"
start on startup
stop on shutdown
exec thumbor -c /etc/thumbor.conf -p 80
post-start script
    PID=`status thumbor | egrep -oi '([0-9]+)$' | head -n1`
    echo $PID > /var/run/thumbor.pid
end script
post-stop script
    rm -f /var/run/thumbor.pid
end script

set, check and run thumbor init file

chmod 755 /etc/init/thumbor.conf && \
init-checkconf /etc/init/thumbor.conf && \
initctl reload-configuration && \
service thumbor start

testing run

thumbor -c /etc/thumbor.conf -p 80