These are the standard Chef cookbooks used by AWS OpsWorks.
If you want to override any template (like the Rails database.yml or the Apache vhost definition), this is the place to look for the originals.
The master branch is the one deployed on the instances.
See also https://aws.amazon.com/opsworks/
LICENSE: Unless otherwise stated, cookbooks/recipes originated by Amazon Web Services are licensed under the Apache 2.0 license. See the LICENSE file. Some files are just imported and authored by others. Their license will of course apply.