As a first step, we recommend creating a directory in your host system that will be later be mapped as Docker volume, and placing your licensekey in this directory. For this example, let's assume the path to the license key on the host system will be "/home/user12/prconfig/licensekey.txt".
In the next step, you should map the "/home/user12/prconfig" directory to a Docker volume. PDFreactor will now automatically detect the license key when the container is started using this configuration:
docker run -d -p 8080:9423 -v /home/user12/prconfig:/ro/config realobjects/pdfreactor