Re: [atomic-devel] Fedora 26 change: using overlayfs as default

[Dusty Mabe <dusty dustymabe com>]

On 12/13/2016 01:02 PM, Colin Walters wrote:
> 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)
> 

So if we were to propose the "overlayfs as default" change for all of
Fedora, would you consider that to be problematic considering your 
"you shouldn't use overlayfs for persistent data," stance. In the case
of a user running pet containers on their local desktop environment,
what is the sentiment?

Dusty