We have installed PIMCore within Docker with the following template: https://github.com/dpfaffenbauer/pimcore-docker-compose
We can print to pdf, although we do not have have any pictures.
The locations are provided, but the pictures do not load.
We guess it must be related to the Hostname (WkHTMLtoPDF) or BaseURL (PDFreactor) with the use with Docker.
According explanation on the Pimcore, this should be correct. I guess this must be related with use with Docker.