Overlapping mounts don't work correctly

[jandubois]

I wanted to keep ~ readonly, but make another directory below it (say, ~/tmp) writable. I get one of 2 results:

1. ~/tmp is still readonly, all of ~ is visible, or
2. ~/tmp is writable, but it is the only entry under ~. ~ is also writable, but files created here are not copied over to the host (unlike files created under ~/tmp.

It seems like a reasonable requirement to make all of ~ readable, but only a subset writable. Using /tmp/lima is a workaround, but fragile as files there are automatically deleted after 3 days.

[afbjorklund]

Have you consider adding data disks as a feature ? It was considered for machine, but never implemented.

But maybe it wouldn't fit into the lima storage model, if it needs to be directly accessible from the host as well.

[jandubois]

Have you consider adding data disks as a feature ? It was considered for machine, but never implemented.

We kind of support data disks (automatically) if the boot image is an ISO. I suspect it only works for Alpine right now.

But maybe it wouldn't fit into the lima storage model, if it needs to be directly accessible from the host as well.

I don't think it fits. Lima provides the illusion that you can run nerdctl directly on it host, and it just works. But it really relies on the host files being mounted at the same location inside the instance, and then nerdctl running inside because it needs direct access to both the source files for building, and the containerd layers to directly manipulate the images.

We need to look again into using samba (#188).

My main worry is that once I test nfsd, it will turn out to be the fastest option. Unfortunately it is clumsy to configure (you need to manipulate /etc/exports on the host, as root), and the Apple implementation is (or used to be) buggy.

I've used it a couple of years ago with Vagrant (also for performance reasons), and while being fast, it sometimes didn't realize a host file was updated and served a cached copy. You had to create a sparsebundle layer on the host to avoid the bug. So yeah, I really hope nfsd isn't still the most performant option in 2021. Or if it is, that at least the bugs have been fixed!

[afbjorklund]

I think virtfs had a nice model, too bad it wasn't merged yet for Darwin. But it was very straightforward to use with qemu and mount (9p).

In terms of performance, I think that vsock and virtiofs had the most promise. But it is not available, "any year now". Since like 2016.

[afbjorklund]

Lima provides the illusion that you can run nerdctl directly on it host, and it just works.

Like Docker... I called it the "Wizard of Oz" model

As in pay no attention to the VM behind the curtain.