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Tool to scan staged files before commit and provide functionality to create configuration file from secret templates

Project description

Git-Heimdall is a guardian/gatekeeper tool for scanning sensitive data before committing files to github. It also provides functionality for creating configuration files from existing template files.

What is Git-Heimdall?

Git-Heimdall is a tool for scanning sensitive data before the staged files are added to a commit. So, if a developer makes some changes in his repository and tries to commit those changes via git commit, those files will be first scanned by Git-Heimdall to check whether there are any sensitive data in those changes and informs developer about it.

This process is automated. You don’t have to run extra commands in order to scan those files. Infact those files are scanned automatically when git commit is called.

Why Git-Heimdall?

Committing sensitive data has been one of the most common vulnerabilities in security world. Developers commit sensitive data and expose it to internet without even realising about it.

This is where Git-Heimdall comes in. Git-Heimdall provides a set of functionalities like :-

  • Scanning files before commit to track secrets
  • Keep configuration files in template format so that there are less chances of everytime modifying the config file and committing of secrets.(More about Git-Heimdall secretfy)


This section provides quick steps of how to setup this tool.

  1. Create a virtual Python environment and install Git-heimdall in it.

    python3 -m venv vheimdall
    . vheimdall/bin/activate
    pip3 install git-heimdall
    heimdall -i
  2. Run Sanity test

    heimdall secretfy -m

    The above command creates mock templates, secrets file at /tmp/git-heimdall directory. The -c or --config option is for providing your config.yaml file.

  3. Register current project with git-heimdall

    heimdall -a <absolute-path-of-project>

    The above command registers your project with heimdall scans. Next time when you try to commit staged files, it would start scanning those files before it gets added to commit and pushed to github.

More about Git-Heimdall secretfy

git-heimdall provides secretfy option for generating config files dynamically from your template files. The templates are nothing but configuration files, which holds your configuration in mustache format.

secretfy tool generates the required configuration file with help of secrets file which would contain the real values required for actual config/properties file.

Let’s just say you have a set of configuration which you keep in a file config.yaml, config.json, etc. These configuration might have some highly sensitive information required to execute your project like your user credentials, email, phone number, private key etc. Everytime, in your development process, you need to add these sensitive values to the config file and remove them before committing the code into github.

This process is pretty painful and often you endup committing one or the other sensitive information to git.

So, instead of having a config file, you can have a template which resembles your config file. Now before executing your project. All you need to do is generate the desired config file with the help of this tool and then follow the usual approach of running the project. The best part is that you don’t have to worry about accidently commit the actual config file to the git repo. That file won’t be shown in git status unless you forcibly add it.


This section describes how to set up a development environment for Git-Heimdall. This section is useful for those who would like to contribute to Git-Heimdall or run Git-Heimdall directly from its source.

We use primarily three tools to perform development on this project: Python 3, Git, and Make. Your system may already have these tools. But if not, here are some brief instructions on how they can be installed.

  1. On macOS, if you have Homebrew installed, then these tools can be be installed easily with the following command:

    brew install python git

    On a Debian GNU/Linux system or in another Debian-based Linux distribution, they can be installed with the following commands:

    apt-get update
    apt-get install python3 python3-venv git make

    On any other system, we hope you can figure out how to install these tools yourself.

  2. Clone the project repository and enter its top-level directory:

    git clone
    cd git-heimdall
  3. Create a virtual Python environment for development purpose:

    make vheimdall deps

    This creates a virtual Python environment at ~/.vheimdall/git-heimdall. Additionally, it also creates a convenience script named vheimdall in the current directory to easily activate the virtual Python environment which we will soon see in the next point.

    To undo this step at anytime in future, i.e., delete the virtual Python environment directory, either enter rm -rf vheimdall ~/.vheimdall/.

  4. Activate the virtual Python environment:

    . ./vheimdall
  5. In the top-level directory of the project, enter this command:

    python3 -m heimdall -i

    This initializes git-heimdall tool. This is just a one time process and need not be run everytime, unless if there is any change in the template resources. This command just updates in the location of the git templateDir in git configuration.

    python3 -m heimdall secretfy -m

    This generates mock data at /tmp/git-heimdall. This step serves as a sanity check that ensures that the development environment is correctly set up. Also, it gives a brief idea of how to create a config in form of template.

  6. Now to simulate the environment and test the tool. Do the following:-

    . ~/.vheimdall/git-heimdall/bin/activate
    mkdir /tmp/git-heimdall-tool-test
    cd /tmp/git-heimdall-tool-test
    echo -n "print('<insert-some-sensitive-value>')" >>
    git init
    git add .
    git commit -m "Sample commit"

    This will start scanning the file and will provide you with the sensitive data that you have in this file. Add more files and play with the tool to familiar yourself.

How to Use

This section provides samples of how to use this tool.

heimdall is initialized once after installation. That can be done for the following :-

heimdall -i

After initialization, any new repository created or cloned will be scanned by heimdall once any staged files are committed.

You can register existing repositories to heimdall to integrate scanning process.

heimdall -reg <absolute-path-of-repo>

heimdall secretfy consist of 3 components :-

Secrets file - This file can be in yaml, json and xml format.

Template files - These files are configuration files in template format. For eg:- If you have a file config.json then your template file will be config.json.mustache.

Extension - This is the file extension of your configuration file. Following are the example config files and their respective extension.

a. config.yaml       : yaml
b. config.xml        : xml
c. config.json       : json
d. : properties

These parameters can be added to a baseconfig.yaml file in the following way

    secret: res/secrets.yaml
          file: res/example.yaml.mustache
          extension: yaml
          file: res/example.json.mustache
          extension: json
          file: res/example.xml.mustache
          extension: xml

The baseconfig.yaml file starts with heimdall tag.

1. secret is the absolute path of the secrets file containing sensitive values.

2. templates tag is an array of template files. All these files are in .mustache format whose sensitive values resides in secrets.yaml file.

  • file is the absolute path of the template file.
  • extension is the extension of the configuration file which will be generated from the template file.

NOTE: Make sure that the template file are in <file_name>.<extension>.<mustache> format.

Run the following command to generate the config files.

heimdall secretfy -c baseconfig.yaml

This will create config files in the respective directories. Note that these configurations won’t be seen in git history. You can check that by doing git status.

Config template file samples


        val2: my_password
        val3: username
        val4: my_private_key


      val1: {{secrets.item.val1}}
      val2: {{secrets.item.val2}}
      result: This is just a dummy description.
      val3: {{secrets.item1.val3}}
      val4: {{secrets.item1.val4}}
      result: This is another dummy description.

The secrets.yaml file contains the sensitive information and example.yaml.mustache is the template file which contains the keys in mustache format. Hence the key secrets.item.val2 has value my_password which will be populated via heimdall secretfy tool.

NOTE: You can run `heimdall secretfy -m` to get more sample baseconfig, templates, secret files. These files will get generated at `/tmp/git-heimdall`.


How can i deploy my code in CICD pipeline or on remote server since it doesn’t have config files and needs to be generated.

You can generate all the config files required for your repository to compile and run in CICD pipeline or at remote server by the following command.

heimdall secretfy -e mustache -s <secrets_file_path> -r <repository_path>

-e is the template extension, -s is the absolute path of the secrets file and -r is absolute path of the repository


To report bugs, suggest improvements, or ask questions, please create a new issue at


This is free software. You are permitted to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of it, under the terms of the MIT License. See for the complete license.

This software is provided WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See for the complete disclaimer.

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