git-secret
A bash-tool to store your private data inside a git repository
...If you do choose to store these secrets unencrypted in your git repo, even if the repository is private, it is a security risk to copy the secrets everywhere you check out your repo. These files are not version controlled. Filenames, locations, and passwords change from time to time, or new information appears, and other information is removed. When secrets are stored separately from your repo, you can not tell for sure which version of the configuration file was used with each commit or deploy. When building the automated deployment system there will be one extra step: download and place these secret-configuration files where they need to be. ...