Generate a JWT from a GitHub App for REST API access by your App

token.sh

# Install JWT Creator https://github.com/trstringer/jwt-creator
go install github.com/trstringer/jwt-creator@latest

# Download GitHub App Private Key as $HOME/app.pem
# https://docs.github.com/en/developers/apps/building-github-apps/authenticating-with-github-apps#generating-a-private-key

# Generate public key from GitHub App Private Key
openssl rsa -in "$HOME/app.pem"  -pubout -out "$HOME/app.pub"

# Generate JWT
APP_ID='123456' # ID Of installed App
PRIVATE_KEY_FILE="$HOME/app.pem"
PUBLIC_KEY_FILE="$HOME/app.pub"
GH_OAUTH_TOKEN=$(jwt-creator create --private-key-file $PRIVATE_KEY_FILE --issued-at-now --expires-in-seconds 300 --issuer $APP_ID)

# Optional verify
jwt-creator verify --public-key-file $PUBLIC_KEY_FILE --token $GH_OAUTH_TOKEN

# Use Token
curl -i -H "Authorization: Bearer ${GH_OAUTH_TOKEN}" -H "Accept: application/vnd.github+json" https://api.github.com/app