git config --global credential.helper "/bin/bash /git_creds.sh"
echo '#!/bin/bash' > /git_creds.sh
echo "sleep 1" >> /git_creds.sh
echo "echo username=$SERVICE_USER" >> /git_creds.sh
echo "echo password=$SERVICE_PASS" >> /git_creds.sh

# to test it
git clone https://my-scm-provider.com/project.git