Currently, the service containers ( like nginx, varnish, phpfpm etc ) cannot assume ezpublish is yet installed because the ezpublish_prepare container might not yet be finish.

For simplicity, we want to make it possible for the service containers to assume ezpublish is installed and ready to run, ie : You cannot start the service containers before you have installed eZ Publish.

For making it easy to install eZ Publish from scratch we'll make a container which is able to install eZ Publish for the user ( from tarball and/or composer ). This basically means to separate out the ezpublish_prepare container and make the other containers independent of it.

Note:
The service containers will in some case still need to inject config changes in the ezpublish installation ( for instance, the varnish containers must let ez publish know the IP if the varnish server as this will be different every time the varnish container starts up