Hi Nicolas, thanks for your feedback 
@Rpi gave the right method, you can launch as many containers as you want, each of them using the internal port 80, but change the outcome port using the mapping parameter ( docker run -p 8080:80 …) or the docker-compose configuration.
… but it didn’t : the jeedom image install and launch its own mariaDB instance, and does not use any other external mariaDB container 
this is why I don’t use the official jeedom image until now, I try to have several distinct containers.
I tried your dockerfile project but didn’t manage, and had an unexpected error. Now I started a new Dockerfile project without using the official jeedom image, but using the official php.apache image. Same strategy as your, that is, install almost dependancies in the dockerfile, and also the current jeedom source from git.
This works for me but I didn’t try with several specific plugins, nor with host mode.
I didn’t try the final step, but it may be the good way to add a shared volume with a jeedom backup, then the final step will import and install the backup (backup restore) and run jeedom with every configuration and plugins already installed.