for scrapy with Python 3, you'll need
sudo apt-get install python3 python-dev python3-dev \
build-essential libssl-dev libffi-dev \libxml2-dev libxslt1-dev zlib1g-dev python-pip
with Python 2, you'll need
sudo apt-get install python-dev \build-essential libssl-dev libffi-dev \libxml2-dev libxslt1-dev zlib1g-dev \python-pip