On Tue, Dec 13, 2016, at 12:45 PM,
Clayton Coleman wrote:
Are the POSIX issues in applications running on
overlay mostly resolved now? I.e. if we flipped the default
would be reasonably able to support a diverse range of Linux
workloads without the risk that previously existed?
overlayfs will never be fully
POSIX compatible, but I think that's OK,
because remember - you shouldn't
use overlayfs for persistent data,
or really anything that's not
code/config files (and we want to get
to where that's overlayfs-type
semantics for builds, and read-only
for deployment). Data should be
in Kube persistent volumes etc.
I think the thing to focus on is
tools that are run during builds - the
yum-in-overlayfs bug is a good
example, because the RPM database
*is* a database which is the type
of workload that's going to
be sensitive to the overlayfs
semantics. How many of those
are there? Probably not many, I
suspect most of the compat
issues with userspace have been
shaken out by now.
(But long term we may end up in a
situation where people
who want to run e.g. rhel5's yum
in a container need to
somehow fall back to devmapper)
I have heard that the issue with yum/rpm is being worked on in the
kernel.