When starting this tutorial on using scrapy to crawl a site on a fresh Ubuntu 16.04 droplet with only python installed via apt install python python-pip - I ran the scrapy install command:

pip install scrapy

and got the following errors:

Failed building wheel for cryptography

and

Command "/usr/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-uMrPxH/cryptography/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-w7GcS0-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /tmp/pip-build-uMrPxH/cryptography/

The Solution

I was missing some vital cryptography libs that scrapy depends on, to install them I ran:

sudo apt-get install build-essential libssl-dev libffi-dev python-dev
pip install cryptography

once that executed I could install scrapy with a pip install scrapy and get on with the excellent tutorial!