.. image:: https://travis-ci.org/erikrose/peep.svg?branch=master :target: https://travis-ci.org/erikrose/peep

.. note::

Peep is deprecated, as we have `merged its functionality into pip 8
<https://pip.readthedocs.org/en/stable/reference/pip_install/#hash-checking
-mode>`_. This brings myriad improvements, including support for caching,
detection of omitted dependencies, and better handling of errors and corner
cases. To switch to pip 8's hash-checking without hitting any race
conditions...

1. Upgrade to peep 3.0 (which exists mainly as a stopgap to support
   race-free upgrades like this).
2. Upgrade to pip 8.
3. Atomically, switch the format of your requirements files using ``peep
   port`` (described below), and start calling pip instead of peep.
4. Delete peep from your project.

Thank you for using peep! Your early support helped establish hash
verification as a feature worth uplifting, and now the package ecosystem is
safer for everyone.

Here are some `more detailed upgrade instructions
<https://github.com/erikrose/peep/wiki/UpgradeToPip8>`_ in case you need
them.

==== Peep

Deploying Python projects has long been a source of frustration for the security-conscious: a compromise of PyPI or its third-party CDN could get you a package different from the one you signed up for. To guarantee known-good dependencies for your deployments, you had to run a local package index, manually uploading packages as you vetted them, maintaining a set of ACLs for that server, and trying to somehow keep an audit trail of who did what. Alternatively, you could check everything into a vendor library, but that meant a lot of fooling around with your VCS (or maintaining custom tooling) to do upgrades.

Peep fixes all that.

Vet your packages, and put hashes of the PyPI-sourced tarballs into requirements.txt, like this::

# sha256: L9XU_-gfdi3So-WEctaQoNu6N2Z3ZQYAOu4-16qor-8
Flask==0.9

# sha256: qF4YU3XbdcEJ-Z7N49VUFfA15waKgiUs9PFsZnrDj0k
Jinja2==2.6

Then, use peep install instead of pip install, and let the crypto do the rest. If a downloaded package doesn't match the expected hash, Peep will freak out, and installation will go no further.

There are no servers to maintain, no enormous vendor libs to wrestle, and no need to trust a package author's key management practices. With the addition of a few hashes to your requirements file, you can know that your chain of trust is safely rooted in your own source tree.

Switching to Peep

1. Install Peep::

   pip install peep

   (Or, better, embed peep.py into your codebase as described in the Embedding section below. That eliminates having to trust an unauthenticated PyPI download, assuming you manually vet peep.py itself the first time.)

2. Use Peep to install your project once::

    cd yourproject
    peep install -r requirements.txt
   

   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: L9XU_-gfdi3So-WEctaQoNu6N2Z3ZQYAOu4-16qor-8

   Flask==0.9

   sha256: qF4YU3XbdcEJ-Z7N49VUFfA15waKgiUs9PFsZnrDj0k

   Jinja2==2.6

   sha256: u_8C3DCeUoRt2WPSlIOnKV_MAhYkc40zNZxDlxCA-as

   Pygments==1.4

   sha256: A1gwhyCNozcxug18_9RjJTmJQa1rctOt-AnP7_yR0PM

   https://github.com/jsocol/commonware/archive/b5544185b2d24adc1eb512735990752400ce9cbd.zip#egg=commonware

   ---

   Not proceeding to installation.

3. Vet the packages coming off PyPI in whatever way you typically do. For instance, read them, or compare them with known-good local copies.

4. 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.)

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

.. warning::

Be careful not to nullify all your work when you install your actual
project. If you use ``python setup.py install``, setuptools will happily go
out and download, unchecked, any requirements you missed in
``requirements.txt`` (and it's easy to miss some as your project evolves).
One way to be safe is to pack up your project and then install that using
pip and ``--no-deps``::

    python setup.py sdist
    pip install --no-deps dist/yourproject-1.0.tar.gz

The Fearsome Warning

If, during installation, a hash doesn't match, Peep will say something like this::

THE FOLLOWING PACKAGES DIDN'T MATCH 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.

    requests: expected FWvz7Ce6nsfgz4--AoCHGAmdIY3kA-tkpxTXO6GimrE
                   got YhddA1kUpMLVODNbhIgHfQn88vioPHLwayTyqwOJEgY

It will then exit with a status of 1. Freak out appropriately.

Other Features

• Peep implicitly turns on pip's --no-deps option so unverified dependencies of your requirements can't sneak through.

• 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.

• Have a manually downloaded package you've vetted? Run peep hash on its tarball (the original, from PyPI--be sure to keep it around) to get its hash line::

  % peep hash nose-1.3.0.tar.gz

  sha256: TmPMMyXedc-Y_61AvnL6aXU96CRpUXMXj3TANP5PUmA

• If a package is already present--which might be the case if you're installing into a non-empty virtualenv--Peep doesn't bother downloading or building it again. It assumes you installed it with Peep in a previous invocation and thus trusts it. The only exception to this is for URL-specified requirements where the URL contains a SHA-like filename (eg https://github.com/foo/bar/archive/<SHA>.zip), since the package version number is typically not incremented for every commit, so Peep cannot be sure the contents have not changed. Note: Re-using a virtualenv during deployment can really speed things up, but you will need to manually remove dependencies that are no longer in the requirements file.

• peep port converts a peep-savvy requirements file to one compatible with pip 8's new hashing functionality <https://pip.pypa.io/en/latest/reference/pip_install/#hash-checking-mode>_::

  % peep port requirements.txt certifi==2015.04.28
  --hash=sha256:268fa00c27de756d71663dd61f73a4a8d8727569bb1b474b2ce6020553826872
  --hash=sha256:99785e6cf715cdcde59dee05a676e99f04835a71e7ced201ca317401c322ba96 click==4.0 --hash=sha256:9ab1d313f99b209f8f71a629f36833030c8d7c72282cf7756834baf567dca662

  Note that comments and URLs don't make it through, but the hard part—hash format conversion—is taken care of for you.

Embedding

Peep was designed for unsupervised continuous deployment scenarios. In such scenarios, manual ahead-of-time preparation on the deployment machine is a liability: one more thing to go wrong. To relieve you of having to install (and upgrade) Peep by hand on your server or build box, we've made Peep embeddable. You can copy the peep.py file directly into your project's source tree and call it from there in your deployment script. This also gives you an obvious starting point for your chain of trust: however you trust your source code is how you trust your copy of Peep, and Peep verifies everything else via hashes. (Equivalent would be if your OS provided Peep as a package--presumably you trust your OS packages already--but this is not yet common.)

Security and Insecurity

Here's what you get for free with Peep--and what you don't.

You get repeatability. If you peep install package Foo==1.2.3, every subsequent install of Foo==1.2.3 will be the same as the original (or Peep will complain).

Peep does not magically vet your packages. Peep is not a substitute for combing through your packages for malicious code or comparing them with known-good versions. If you don't vet them, they are not vetted.

Peep does not make authors or indices trustworthy. All Peep does is guarantee that subsequent downloads of Foo==1.2.3 are the same as the first one. It doesn't guarantee the author of that package is trustworthy. It doesn't guarantee that the author of that package is the one who released that package. It doesn't guarantee that the package index is trustworthy.

Troubleshooting

Multiple Hashes: Architecture-Specific Packages and Old Versions of PyPI

Are you suddenly getting the Fearsome Warning? Maybe you're really in trouble, but maybe something more innocuous is happening.

If your packages install from wheels or other potentially architecture-specific sources, their hashes will obviously differ across platforms. If you deploy on more than one, you'll need more than one hash.

Also, some packages offer downloads in multiple formats: for example, zips and tarballs, or zips and wheels. Which version gets downloaded can vary based on your version of pip, meaning some packages may effectively have more than one valid hash.

To support these scenarios, you can stack up multiple known-good hashes above a requirement, as long as they are within a contiguous block of commented lines::

# Tarball:
# sha256: lvpN706AIAvoJ8P1EUfdez-ohzuSB-MyXUe6Rb8ppcE
#
# And th