This project helps you generate a JWT from a private key and is meant for developers of GitHub apps.
Make sure you are the publisher of a GitHub App (not a GitHub oAuth App), and create a private key to access that app.
Visit Authenticating with GitHub Apps, which has more on the topic.
Once you have a private key, download it to your computer at /path/to/key.pem.
Clone this repo:
git clone https://github.com/dcycle/docker-gh-key-to-jwt.git
cd docker-gh-key-to-jwt
Generate a JWT which expires after 10 minutes. This takes three arguments, first the path to the directory contain your private key ("/path/to"); second, the filename of your private key ("key.pem"); and third, your GitHub app's ID:
# This uses the ruby script
./scripts/generate-jwt.sh /path/to key.pem 12345
TO use the Javascript script, you can use:
./scripts/generate-jwt-js.sh /path/to key.pem 12345