===========
git-secrets
===========

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Prevents you from committing passwords and other sensitive information to a git repository.
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.. contents:: :depth: 2

Synopsis
--------

::

    git secrets --scan [-r|--recursive] [--cached] [--no-index] [--untracked] [<files>...]
    git secrets --scan-history
    git secrets --install [-f|--force] [<target-directory>]
    git secrets --list [--global]
    git secrets --add [-a|--allowed] [-l|--literal] [--global] <pattern>
    git secrets --add-provider [--global] <command> [arguments...]
    git secrets --register-aws [--global]
    git secrets --aws-provider [<credentials-file>]


Description
-----------

``git-secrets`` scans commits, commit messages, and ``--no-ff`` merges to
prevent adding secrets into your git repositories. If a commit,
commit message, or any commit in a ``--no-ff`` merge history matches one of
your configured prohibited regular expression patterns, then the commit is
rejected.


Installing git-secrets
----------------------

``git-secrets`` must be placed somewhere in your PATH so that it is picked up
by ``git`` when running ``git secrets``.

\*nix (Linux/macOS)
~~~~~~~~~~~~~~~~~~~

You can use the ``install`` target of the provided Makefile to install ``git secrets`` and the man page.
You can customize the install path using the PREFIX and MANPREFIX variables.

::

    make install

Windows
~~~~~~~

Run the provided ``install.ps1`` powershell script. This will copy the needed files
to an installation directory (``%USERPROFILE%/.git-secrets`` by default) and add
the directory to the current user ``PATH``.

::

    PS > ./install.ps1

Homebrew (for macOS users)
~~~~~~~~~~~~~~~~~~~~~~~~~~

::

    brew install git-secrets

.. warning::

    **You're not done yet! You MUST install the git hooks for every repo that
    you wish to use with** ``git secrets --install``.

Here's a quick example of how to ensure a git repository is scanned for secrets
on each commit::

    cd /path/to/my/repo
    git secrets --install
    git secrets --register-aws


Advanced configuration
----------------------

Add a configuration template if you want to add hooks to all repositories you
initialize or clone in the future.

::

    git secrets --register-aws --global


Add hooks to all your local repositories.

::

    git secrets --install ~/.git-templates/git-secrets
    git config --global init.templateDir ~/.git-templates/git-secrets


Add custom providers to scan for security credentials.

::

    git secrets --add-provider -- cat /path/to/secret/file/patterns


Before making public a repository
---------------------------------

With git-secrets is also possible to scan a repository including all revisions:

::

    git secrets --scan-history


Options
-------

Operation Modes
~~~~~~~~~~~~~~~

Each of these options must appear first on the command line.

``--install``
    Installs git hooks for a repository. Once the hooks are installed for a git
    repository, commits and non-fast-forward merges for that repository will be prevented
    from committing secrets.

``--scan``
    Scans one or more files for secrets. When a file contains a secret, the
    matched text from the file being scanned will be written to stdout and the
    script will exit with a non-zero status. Each matched line will be written with
    the name of the file that matched, a colon, the line number that matched,
    a colon, and then the line of text that matched. If no files are provided,
    all files returned by ``git ls-files`` are scanned.

``--scan-history``
    Scans repository including all revisions. When a file contains a secret, the
    matched text from the file being scanned will be written to stdout and the
    script will exit with a non-zero status. Each matched line will be written with
    the name of the file that matched, a colon, the line number that matched,
    a colon, and then the line of text that matched.

``--list``
    Lists the ``git-secrets`` configuration for the current repo or in the global
    git config.

``--add``
    Adds a prohibited or allowed pattern.

``--add-provider``
    Registers a secret provider. Secret providers are executables that when
    invoked output prohibited patterns that ``git-secrets`` should treat as
    prohibited.

``--register-aws``
    Adds common AWS patterns to the git config and ensures that keys present
    in ``~/.aws/credentials`` are not found in any commit. The following
    checks are added:

    - AWS Access Key IDs via ``(A3T[A-Z0-9]|AKIA|AGPA|AIDA|AROA|AIPA|ANPA|ANVA|ASIA)[A-Z0-9]{16}``
    - AWS Secret Access Key assignments via ":" or "=" surrounded by optional
      quotes
    - AWS account ID assignments via ":" or "=" surrounded by optional quotes
    - Allowed patterns for example AWS keys (``AKIAIOSFODNN7EXAMPLE`` and
      ``wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY``)
    - Known credentials from ``~/.aws/credentials``

    .. note::

        While the patterns registered by this command should catch most
        instances of AWS credentials, these patterns are **not** guaranteed to
        catch them **all**. ``git-secrets`` should be used as an extra means of
        insurance -- you still need to do your due diligence to ensure that you
        do not commit credentials to a repository.

``--aws-provider``
    Secret provider that outputs credentials found in an INI file. You can
    optionally provide the path to an INI file.


Options for ``--install``
~~~~~~~~~~~~~~~~~~~~~~~~~

``-f, --force``
    Overwrites existing hooks if present.

``<target-directory>``
    When provided, installs git hooks to the given directory. The current
    directory is assumed if ``<target-directory>`` is not provided.

    If the provided ``<target-directory>`` is not in a git repository, the
    directory will be created and hooks will be placed in
    ``<target-directory>/hooks``. This can be useful for creating git template
    directories using with ``git init --template <target-directory>``.

    You can run ``git init`` on a repository that has already been initialized.
    From the `git init documentation <https://git-scm.com/docs/git-init>`_:

        From the git documentation: Running ``git init`` in an existing repository
        is safe. It will not overwrite things that are already there. The
        primary reason for rerunning ``git init`` is to pick up newly added
        templates (or to move the repository to another place if
        ``--separate-git-dir`` is given).

    The following git hooks are installed:

    1. ``pre-commit``: Used to check if any of the files changed in the commit
       use prohibited patterns.
    2. ``commit-msg``: Used to determine if a commit message contains a
       prohibited patterns.
    3. ``prepare-commit-msg``: Used to determine if a merge commit will
       introduce a history that contains a prohibited pattern at any point.
       Please note that this hook is only invoked for non fast-forward merges.

    .. note::

        Git only allows a single script to be executed per hook. If the
        repository contains Debian-style subdirectories like ``pre-commit.d``
        and ``commit-msg.d``, then the git hooks will be installed into these
        directories, which assumes that you've configured the corresponding
        hooks to execute all of the scripts found in these directories. If
        these git subdirectories are not present, then the git hooks will be
        installed to the git repo's ``.git/hooks`` directory.


Examples
^^^^^^^^

Install git hooks to the current directory::

    cd /path/to/my/repository
    git secrets --install

Install git hooks to a repository other than the current directory::

    git secrets --install /path/to/my/repository

Create a git template that has ``git-secrets`` installed, and then copy that
template into a git repository::

    git secrets --install ~/.git-templates/git-secrets
    git init --template ~/.git-templates/git-secrets

Overwrite existing hooks if present::

    git secrets --install -f


Options for ``--scan``
~~~~~~~~~~~~~~~~~~~~~~

``-r, --recursive``
    Scans the given files recursively. If a directory is encountered, the
    directory will be scanned. If ``-r`` is not provided, directories will be
    ignored.

    ``-r`` cannot be used alongside ``--cached``, ``--no-index``, or
    ``--untracked``.

``--cached``
    Searches blobs registered in the index file.

``--no-index``
    Searches files in the current directory that is not managed by git.

``--untracked``
    In addition to searching in the tracked files in the working tree,
    ``--scan`` also in untracked files.

``<files>...``
    The path to one or more files on disk to scan for secrets.

    If no files are provided, all files returned by ``git ls-files`` are
    scanned.


Examples
^^^^^^^^

Scan all files in the repo::

    git secrets --scan

Scans a single file for secrets::

    git secrets --scan /path/to/file

Scans a directory recursively for secrets::

    git secrets --scan -r /path/to/directory

Scans multiple files for secrets::

    git secrets --scan /path/to/file /path/to/other/file

You can scan by globbing::

    git secrets --scan /path/to/directory/*

Scan from stdin::

    echo 'hello!' | git secrets --scan -


Options for ``--list``
~~~~~~~~~~~~~~~~~~~~~~

``--global``
    Lists only git-secrets configuration in the global git config.


Options for ``--add``
~~~~~~~~~~~~~~~~~~~~~

``--global``
    Adds patterns to the global git config

``-l, --literal``
    Escapes special regular expression characters in the provided pattern so
    that the pattern is searched for literally.

``-a, --allowed``
    Mark the pattern as allowed instead of prohibited. Allowed patterns are
    used to filter out false positives.

``<pattern>``
    The regex pattern to search.


Examples
^^^^^^^^

Adds a prohibited pattern to the current repo::

    git secrets --add '[A-Z0-9]{20}'

Adds a prohibited pattern to the global git config::

    git secrets --add --global '[A-Z0-9]{20}'

Adds a string that is scanned for literally (``+`` is escaped)::

    git secrets --add --literal 'foo+bar'

Add an allowed pattern::

    git secrets --add -a 'allowed pattern'


Options for ``--register-aws``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``--global``
    Adds AWS specific configuration variables to the global git config.


Options for ``--aws-provider``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``[<credentials-file>]``
    If provided, specifies the custom path to an INI file to scan. If not
    provided, ``~/.aws/credentials`` is assumed.


Options for ``--add-provider``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``--global``
    Adds the provider to the global git config.

``<command>``
    Provider command to invoke. When invoked the command is expected to write
    prohibited patterns separated by new lines to stdout. Any extra arguments
    provided are passed on to the command.


Examples
^^^^^^^^

Registers a secret provider with arguments::

    git secrets --add-provider -- git secrets --aws-provider

Cats secrets out of a file::

    git secrets --add-provider -- cat /path/to/secret/file/patterns


Defining prohibited patterns
----------------------------

``egrep``-compatible regular expressions are used to determine if a commit or
commit message contains any prohibited patterns. These regular expressions are
defined using the ``git config`` command. It is important to note that
different systems use different versions of egrep. For example, when running on
macOS, you will use a different version of ``egrep`` than when running on something
like Ubuntu (BSD vs GNU).

You can add prohibited regular expression patterns to your git config using
``git secrets --add <pattern>``.


Ignoring false positives
------------------------

Sometimes a regular expression might match false positives. For example, git
commit SHAs look a lot like AWS access keys. You can specify many different
regular expression patterns as false positives using the following command:

::

    git secrets --add --allowed 'my regex pattern'

You can also add regular expressions patterns to filter false positives to a
``.gitallowed`` file located in the repository's root directory. Lines starting
with ``#`` are skipped (comment line) and empty lines are also skipped.

First, git-secrets will extract all lines from a file that contain a prohibited
match. Included in the matched results will be the full path to the name of
the file that was matched, followed by ':', followed by the line number that was
matched, followed by the entire line from the file that was matched by a secret
pattern. Then, if you've defined allowed regular expressions, git-secrets will
check to see if all of the matched lines match at least one of your registered
allowed regular expressions. If all of the lines that were flagged as secret
are canceled out by an allowed match, then the subject text does not contain
any secrets. If any of the matched lines are not matched by an allowed regular
expression, then git-secrets will fail the commit/merge/message.

.. important::

    Just as it is a bad practice to add prohibited patterns that are too
    greedy, it is also a bad practice to add allowed patterns that are too
    forgiving. Be sure to test out your patterns using ad-hoc calls to
    ``git secrets --scan $filename`` to ensure they are working as intended.


Secret providers
----------------

Sometimes you want to check for an exact pattern match against a set of known
secrets. For example, you might want to ensure that no credentials present in
``~/.aws/credentials`` ever show up in a commit. In these cases, it's better to
leave these secrets in one location rather than spread them out across git
repositories in git configs. You can use "secret providers" to fetch these
types of credentials. A secret provider is an executable that when invoked
outputs prohibited patterns separated by new lines.

You can add secret providers using the ``--add-provider`` command::

    git secrets --add-provider -- git secrets --aws-provider

Notice the use of ``--``. This ensures that any arguments associated with the
provider are passed to the provider each time it is invoked when scanning
for secrets.


Example walkthrough
-------------------

Let's take a look at an example. Given the following subject text (stored in
``/tmp/example``)::

    This is a test!
    password=ex@mplepassword
    password=******
    More test...

And the following registered patterns:

::

    git secrets --add 'password\s*=\s*.+'
    git secrets --add --allowed --literal 'ex@mplepassword'

Running ``git secrets --scan /tmp/example``, the result will
result in the following error output::

    /tmp/example:3:password=******

    [ERROR] Matched prohibited pattern

    Possible mitigations:
    - Mark false positives as allowed using: git config --add secrets.allowed ...
    - List your configured patterns: git config --get-all secrets.patterns
    - List your configured allowed patterns: git config --get-all secrets.allowed
    - Use --no-verify if this is a one-time false positive

Breaking this down, the prohibited pattern value of ``password\s*=\s*.+`` will
match the following lines::

    /tmp/example:2:password=ex@mplepassword
    /tmp/example:3:password=******

...But the first match will be filtered out due to the fact that it matches the
allowed regular expression of ``ex@mplepassword``. Because there is still a
remaining line that did not match, it is considered a secret.

Because that matching lines are placed on lines that start with the filename
and line number (e.g., ``/tmp/example:3:...``), you can create allowed
patterns that take filenames and line numbers into account in the regular
expression. For example, you could whitelist an entire file using something
like::

    git secrets --add --allowed '/tmp/example:.*'
    git secrets --scan /tmp/example && echo $?
    # Outputs: 0

Alternatively, you could allow a specific line number of a file if that
line is unlikely to change using something like the following:

::

    git secrets --add --allowed '/tmp/example:3:.*'
    git secrets --scan /tmp/example && echo $?
    # Outputs: 0

Keep this in mind when creating allowed patterns to ensure that your allowed
patterns are not inadvertently matched due to the fact that the filename is
included in the subject text that allowed patterns are matched against.


Skipping validation
-------------------

Use the ``--no-verify`` option in the event of a false positive match in a
commit, merge, or commit message. This will skip the execution of the
git hook and allow you to make the commit or merge.


About
------

- Author: `Michael Dowling <https://github.com/mtdowling>`_
- Issue tracker: This project's source code and issue tracker can be found at
  `https://github.com/awslabs/git-secrets <https://github.com/awslabs/git-secrets>`_
- Special thanks to Adrian Vatchinsky and Ari Juels of Cornell University for
  providing suggestions and feedback.

Copyright 2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.