Improve searching for configured AWS credentials

The previous approach for finding AWS credentials was pretty naive and
only covered contents of a single file (~/.aws/credentials by
default).

The AWS CLI documentation states various other ways to configure
credentials which weren't covered:
https://docs.aws.amazon.com/cli/latest/topic/config-vars.html#credentials
Even that aren't all ways, a look into the code shows:
https://github.com/boto/botocore/blob/develop/botocore/credentials.py

This commit changes the behavior so the hook will behave in a way
that if the AWS CLI is able to obtain credentials from local files,
the hook will find them as well.

The changes in detail are:
- detect AWS session tokens and handle them like secret keys.
- always search credentials in the default AWS CLI file locations
  ( ~/.aws/config, ~/.aws/credentials, /etc/boto.cfg and ~/.boto)
- detect AWS credentials configured via environment variables in
  AWS_SECRET_ACCESS_KEY, AWS_SECURITY_TOKEN and AWS_SESSION_TOKEN
- check additional configuration files configured via environment
  variables (AWS_CREDENTIAL_FILE, AWS_SHARED_CREDENTIALS_FILE and
  BOTO_CONFIG)
- print out the first four characters of each secret found in files to
  be checked in, to make it easier to figure out, what the secrets
  were, which were going to be checked in
- improve error handling for parsing ini-files
- improve tests

There is a major functional change introduced by this commit:
Locations the AWS CLI gets credentials from are always searched and
there is no way to disable them. --credentials-file is still there to
specify one or more additional files to search credentials in. It's
the purpose of this hook to find and check files for found
credentials, so it should work in any case. As this commit also
improves error handling for not-existing or malformed configuration
files, it should be no big deal.

Receiving credentials via the EC2 and ECS meta data services is not
covered intentionally, to not further increase the amount of changes
in this commit and as it's probably an edge case anyway to have this
hook running in such an environment.
10 files changed
tree: 71435491c5e8ffde413ff0b512ab7115b0796201
  1. pre_commit_hooks/
  2. testing/
  3. tests/
  4. .coveragerc
  5. .gitignore
  6. .pre-commit-config.yaml
  7. .travis.yml
  8. appveyor.yml
  9. CHANGELOG
  10. get-git-lfs.py
  11. hooks.yaml
  12. LICENSE
  13. Makefile
  14. README.md
  15. requirements-dev.txt
  16. setup.cfg
  17. setup.py
  18. tox.ini
README.md

Build Status Coverage Status Build status

pre-commit-hooks

Some out-of-the-box hooks for pre-commit.

See also: https://github.com/pre-commit/pre-commit

Using pre-commit-hooks with pre-commit

Add this to your .pre-commit-config.yaml

-   repo: git://github.com/pre-commit/pre-commit-hooks
    sha: ''  # Use the sha you want to point at
    hooks:
    -   id: trailing-whitespace
    # -   id: ...

Hooks available

  • autopep8-wrapper - Runs autopep8 over python source.
    • Ignore PEP 8 violation types with args: ['-i', '--ignore=E000,...'] or through configuration of the [pep8] section in setup.cfg / tox.ini.
  • check-added-large-files - Prevent giant files from being committed.
    • Specify what is “too large” with args: ['--maxkb=123'] (default=500kB).
  • check-ast - Simply check whether files parse as valid python.
  • check-byte-order-marker - Forbid files which have a UTF-8 byte-order marker
  • check-case-conflict - Check for files with names that would conflict on a case-insensitive filesystem like MacOS HFS+ or Windows FAT.
  • check-docstring-first - Checks for a common error of placing code before the docstring.
  • check-json - Attempts to load all json files to verify syntax.
  • check-merge-conflict - Check for files that contain merge conflict strings.
  • check-symlinks - Checks for symlinks which do not point to anything.
  • check-xml - Attempts to load all xml files to verify syntax.
  • check-yaml - Attempts to load all yaml files to verify syntax.
  • debug-statements - Check for pdb / ipdb / pudb statements in code.
  • detect-aws-credentials - Checks for the existence of AWS secrets that you have set up with the AWS CLI. The following arguments are available:
    • --credential-file - additional AWS CLI style configuration file in a non-standard location to fetch configured credentials from. Can be repeated multiple times.
  • detect-private-key - Checks for the existence of private keys.
  • double-quote-string-fixer - This hook replaces double quoted strings with single quoted strings.
  • end-of-file-fixer - Makes sure files end in a newline and only a newline.
  • fix-encoding-pragma - Add # -*- coding: utf-8 -*- to the top of python files.
    • To remove the coding pragma pass --remove (useful in a python3-only codebase)
  • flake8 - Run flake8 on your python files.
  • forbid-new-submodules - Prevent addition of new git submodules.
  • name-tests-test - Assert that files in tests/ end in _test.py.
    • Use args: ['--django'] to match test*.py instead.
  • pyflakes - Run pyflakes on your python files.
  • pretty-format-json - Checks that all your JSON files are pretty. “Pretty” here means that keys are sorted and indented. You can configure this with the following commandline options:
    • --autofix - automatically format json files
    • --indent ... - Control the indentation (either a number for a number of spaces or a string of whitespace). Defaults to 4 spaces.
    • --no-sort-keys - when autofixing, retain the original key ordering (instead of sorting the keys)
    • --top-keys comma,separated,keys - Keys to keep at the top of mappings.
  • requirements-txt-fixer - Sorts entries in requirements.txt
  • trailing-whitespace - Trims trailing whitespace.
    • Markdown linebreak trailing spaces preserved for .md and.markdown; use args: ['--markdown-linebreak-ext=txt,text'] to add other extensions, args: ['--markdown-linebreak-ext=*'] to preserve them for all files, or args: ['--no-markdown-linebreak-ext'] to disable and always trim.

As a standalone package

If you‘d like to use these hooks, they’re also available as a standalone package.

Simply pip install pre-commit-hooks