The pod definition:
Mesos agent logs:
Note that container_path has to be an absolute path in this case. If container_path is relative, that means it’s a volume from a subdirectory in the container sandbox to another subdirectory in the container sandbox. In that case, the user can just create a symlink, instead of using a volume.
The code constructing SELF SANDBOX_PATH volume was dead up until recently. And Mesos agent validation was made stricter in Sep, 2017. That's why ephemeral volumes for pods do not work anymore.