Re: App image experiments

[Alexander Larsson <alexl redhat com>]

> On Mon, 2013-02-25 at 17:18 +0100, Alexander Larsson wrote:
> > Given that we don't currently have any union fs upstream the only
> way
> > we can do this currently is to use bind mounts. So, I've written a
> > small app to test this. It takes a directory with the base os and
> > a set of squashfs images, then it clones to get a new namespace
> > where it mounts a tmpfs. Inside it we mount loopback mount the
> images
> > and create a directory "root" where we build up the merged
> structure.
> > Any dir/file just in one of the sources gets bind-mounted in, but
> > if any directory is in multiple sources we create it on the tmpfs
> and
> > merge in the the children recursively.
>
> Looks like overlayfs is getting merged for 3.10:
> http://lwn.net/SubscriberLink/542707/4a9a00792c8b9ba5/
>
> > Yowzers! 5000 bind mounts! But i can run gtk3-demo and it works.
>
> This is likely going to be more efficient (and less resource
> intensive)
> than bind-mounting 5k mounts :)

I'll believe it when i see it (its been a long time), but yeah, if this
land its obviously a better approach (although it has some issues with
the limited fs stacking depth).