alpine, virtiofs: `/etc/fstab` contains `timezone: Asia/Tokyo`

[AkihiroSuda]

$ limactl -v
limactl version 0.20.1

$ limactl start --vm-type=vz --mount-type=virtiofs template://alpine 

$ limactl shell alpine cat /etc/fstab
# /etc/fstab
#LIMA-START
mount0	/Users/suda	virtiofs	ro,nofail	0	0
mount1	/tmp/lima	virtiofs	rw,nofail	0	0
timezone: Asia/Tokyo
#LIMA-END

Seems specific to alpine + virtiofs

[jandubois]

This is truly bizarre:

$ limactl shell alpine cat /etc/fstab
# /etc/fstab
#LIMA-START
mount0	/Users/suda	virtiofs	ro,nofail	0	0
mount1	/tmp/lima	virtiofs	rw,nofail	0	0
timezone: Asia/Tokyo
#LIMA-END

The only place we use the #LIMA-START marker is in /etc/environment.

There is no code in lima-init that writes to /etc/fstab, and the only place in the boot scripts is 05-lima-mounts, but it is only executed for selinux, and doesn't add these markers.

And as far as I can tell the only place timezone: Asia/Tokyo would be in user-data, and I don't see where that would be copied to /etc/fstab either.

I'll try to repro later.

[jandubois]

I'll try to repro later.

Happens to me too:

$ limactl shell alpine cat /etc/fstab
# /etc/fstab
#LIMA-START
mount0	/Users/jan	virtiofs	ro,nofail	0	0
mount1	/tmp/lima	virtiofs	rw,nofail	0	0
timezone: America/Vancouver
#LIMA-END

Still don't understand how this is even possible.

[jandubois]

I figured it out. My confusion comes from the fact that the Rancher Desktop fork of alpine-lima has a PR Create a mount script instead of editing /etc/fstab #15 that is not in the upstream repo.

This PR replaced the code that edited /etc/fstab and added the #LIMA-* markers with a separate mount script (to support mounting filenames with spaces in them).

I see the responsible code in upstream at https://github.com/lima-vm/alpine-lima/blob/main/lima-init.sh#L48-L68.

And it explains the timezone: line because there was supposed to be a newline after the mounts block, but timezome: appears directly behind it:

mounts:
- [mount0, /Users/jan, virtiofs, "ro,nofail", "0", "0"]
- [mount1, /tmp/lima, virtiofs, "rw,nofail", "0", "0"]
timezone: America/Vancouver

Since the mounts are modified via regular expressions, that just don't match on the timezone: line, it is copied verbatim.

Now the question is if the Rancher Desktop PR is appropriate for the Lima repo, or if we should fix the lima-init.sh script to break the block as soon as a line doesn't start with a -.

---

I have no idea why the PR never made it into the upstream repo; I guess I should audit the whole diff to see if anything else was dropped accidentally.

[jandubois]

The same thing happens with QEMU and 9p:

lima-alpine:~# cat /etc/fstab
# /etc/fstab
#LIMA-START
mount0	/Users/jan	9p	ro,trans=virtio,version=9p2000.L,msize=131072,cache=fscache,nofail	0	0
mount1	/tmp/lima	9p	rw,trans=virtio,version=9p2000.L,msize=131072,cache=mmap,nofail	0	0
timezone: America/Vancouver
#LIMA-END

It doesn't happen for reverse-sshfs because the user-data template omits the mounts: section:

{{- if or (eq .MountType "9p") (eq .MountType "virtiofs") }}
{{- if .Mounts }}
mounts:
  {{- range $m := $.Mounts}}
- [{{$m.Tag}}, {{$m.MountPoint}}, {{$m.Type}}, "{{$m.Options}}", "0", "0"]
  {{- end }}
{{- end }}
{{- end }}

The simplest fix would be to insert a blank line before the timezone (because the {{- … } part eats the newline before the template block):

--- pkg/cidata/cidata.TEMPLATE.d/user-data
+++ pkg/cidata/cidata.TEMPLATE.d/user-data
@@ -21,6 +21,7 @@ mounts:
 {{- end }}

 {{- if .TimeZone }}
+
 timezone: {{.TimeZone}}
 {{- end }}

[jandubois]

the question is if the Rancher Desktop PR is appropriate for the Lima repo

Yes, it is needed to successfully mount directories whose names contain spaces. I'll create a PR.

[jandubois]

I believe this is fixed:

$ limactl shell alpine cat /etc/fstab
# /etc/fstab
$ limactl shell alpine cat /etc/timezone
America/Vancouver