The overlay filesystem does not support inotify at this time. The
resolv.conf updater test was passing on overlay-based Jenkins because of
a fluke--because it was DIND, /etc/resolv.conf on the "host" was really
a bind-mounted resolv.conf from the outer container, which means a watch
directly on that file worked as it was not overlay backed. The new test
(from #10703) unmounts the bind-mounted copy to test create and modify
code-paths, which caused us to hit the issue.
This PR also adds a note to the docs about the lack of auto-update when
using the overlay storage driver.
See https://lkml.org/lkml/2012/2/28/223 for more info on inotify and
overlay.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
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