By default the port 5432 to is only available to the Docker host itself and you are not be able to reach the internal port on the Docker portaldb container.
from a remote machine,you can make docker publish the port for the outside world by running :
docker service update --publish-add "5432:5432" portal_portaldb --detach=false
This will add the port 5432 from the docker portaldb container a public port 5432 on the local docker service.
After that you are can connect to the Postgress database from a remote box using PgAdmin. on port 5432