Linking containers in swarm using filter not working

Setup of my swarm:
3 servers from which two have label sort=db and one label sort=app. When starting the database container with constraint:sort==db the container ends up as expected on the a server with label db. The name of this container is thedb.
When starting a dependent container with --link thedb:thedb and -e constraint:sort==app the startup will fail because it can’t find the linked container. However if I remove the -e constraint:sort==app the container does startup but is located next to the thedb container on a server with label db.

We are using a file based setup of the swarm, so no swarm agent is running on the different servers.

My questions:
Is it correct that the given constraint is also used to lookup the container specified in the --link?
Are linked containers always deployed on the server running the container it depends on.

Any pointer is welcome.



I forgot to mention, I use docker version 1.6, this is due to the use of centos 6. This weekend we try to move over to centos 7 and docker 1.7. Hopefully linking between containers over multiple hosts will work then.

Answer: I seems I have to wait for version 1.8.0. So for now going to setup an environment with the 1.8.0dev version to try it out