peep 0.2

A "pip install" that is cryptographically guaranteed repeatable

Historically, deploying Python projects has been a pain in the neck if you want any kind of security. PyPI lets package authors change the contents of their packages without revving the version number, and, until very recently, there was no support for HTTPS, leaving it open to man-in-the-middle attacks. If you wanted to guarantee known-good dependencies for your deployment, you had to either run a local PyPI mirror, manually uploading packages as you vetted them, or you had to check everything into a vendor library, necessitating a lot of fooling around with your VCS (or maintaining custom tooling) to do upgrades.

Peep fixes all that.

Vet your packages, put hashes of the PyPI-sourced tarballs into requirements.txt, use peep install instead of pip install, and let the crypto do the rest. If a downloaded package doesn’t match the hash, peep will freak out, and installation will go no further. No servers to maintain, no enormous vendor libs to wrestle. Just requirements.txt with some funny-looking comments and peace of mind.

Switching to Peep

0. Install peep:

   pip install peep

1. Use peep install -r requirements.txt to install your project once. You’ll get output like this:

   <a bunch of pip output>
   
   The following packages had no hashes specified in the requirements file,
   which leaves them open to tampering. Vet these packages to your
   satisfaction, then add these "sha256" lines like so:
   
       # sha256: qF4YU3XbdcEJ-Z7N49VUFfA15waKgiUs9PFsZnrDj0k
       Jinja2==x.y.z
   
       # sha256: u_8C3DCeUoRt2WPSlIOnKV_MAhYkc40zNZxDlxCA-as
       Pygments==x.y.z
   
       # sha256: EIw9QftwHEr07wDo677cFHYyyCJHvreYyNhlehKBAgY
       Werkzeug==x.y.z
   
       # sha256: FWvz7Ce6nsfgz4--AoCHGAmdIY3kA-tkpxTXO6GimrE
       requests==x.y.z
   
   Not proceeding to installation.

2. Vet the packages coming off PyPI in whatever way you typically do.

3. Add the recommended hash lines to your requirements.txt, each one directly above the requirement it applies to. (The hashes are of the original, compressed tarballs from PyPI.)

4. In the future, always use peep install to install your requirements. You are now cryptographically safe!

The Fearsome Warning

If, during installation, a hash doesn’t match, peep will say something like this:

THE FOLLOWING PACKAGES DIDN'T MATCHES THE HASHES SPECIFIED IN THE
REQUIREMENTS FILE. If you have updated the package versions, update the
hashes. If not, freak out, because someone has tampered with the packages.

    futures: expected goofYhddA1kUpMLVODNbhIgHfQn88vioPHLwayTyqwOJEgY
                  got YhddA1kUpMLVODNbhIgHfQn88vioPHLwayTyqwOJEgY

…and will exit with a status of 1. Freak out appropriately.

Other Niceties

• peep implicitly turns on pip’s --no-deps option, because obviously you’ll need to list all your packages in your requirements file in order to specify hashes for all of them.

• All non-install commands just fall through to pip, so you can use peep all the time if you want. This comes in handy for existing scripts that have a big $PIP=/path/to/pip at the top.

• peep-compatible requirements files remain entirely usable with pip, because the hashes are just comments, after all.

Version History

0.2

• Fix repeated-logging bug.

• Fix spurious error message about not having any requirements files.

• Pass pip’s exit code through to the outside for calls to non-install subcommands.

• Improve spacing in the final output.

0.1

• Proof of concept. Does all the crypto stuff. Should be secure. Some rough edges in the UI.