Merge ~xnox/cloud-initramfs-tools:master into cloud-initramfs-tools:master

[Dimitri John Ledkov]

Allow booting ephemeral rw overlayroot squashfs without fstab.

- Do not attempt to overlayrootify non-existing fstab, and mount
  rootfs rw thus removing need to generate any fstab entries; remount
  ro; for systemd to generate mount unit; and remount as rw again.

LP: #1890803

[Dimitri John Ledkov (xnox)]

How can I retest this with curtin's vmtests?

[Dimitri John Ledkov (xnox)]

I'd call this a MAAS bug too, why does it specify "ro" if it clearly wants ephemeral "rw" layer.

[Dimitri John Ledkov (xnox)]

Or does this too miss something?

I'm struggling to see reasons to (re)mount the overlayfs layer 3 times.

[Ryan Harper (raharper)]

> How can I retest this with curtin's vmtests?

In the bug I showed the repack instructions, I'll leave repacking the boot-initrd from MAAS to you.

Once done, you can

% git clone lp:curtin
% cd curtin
% make vmtest-deps
# run this you can control-c it after it syncs the groovy kernel/initrd/squashfs
% rm -rf output/; CURTIN_VMTEST_IMAGE_SYNC=1 ./tools/jenkins-runner tests/vmtests/test_basic.py:GroovyTestBasic
# replace the boot-initrd with your repack
% mv /srv/images/groovy/amd64/20200811/ga-20.10/boot-initrd /srv/images/groovy/amd64/20200811/ga-20.10/boot-initrd.orig
% cp boot-initrd.fixed /srv/images/groovy/amd64/20200811/ga-20.10/boot-initrd
% rm -rf ./output; ./tools/jenkins-runner tests/vmtests/test_basic.py:GroovyTestBasic

[Dimitri John Ledkov (xnox)]

Thanks!

On Thu, 13 Aug 2020 at 00:31, Ryan Harper <email address hidden> wrote:
>
> > How can I retest this with curtin's vmtests?
>
> In the bug I showed the repack instructions, I'll leave repacking the boot-initrd from MAAS to you.
>
> Once done, you can
>
> % git clone lp:curtin
> % cd curtin
> % make vmtest-deps
> # run this you can control-c it after it syncs the groovy kernel/initrd/squashfs
> % rm -rf output/; CURTIN_VMTEST_IMAGE_SYNC=1 ./tools/jenkins-runner tests/vmtests/test_basic.py:GroovyTestBasic
> # replace the boot-initrd with your repack
> % mv /srv/images/groovy/amd64/20200811/ga-20.10/boot-initrd /srv/images/groovy/amd64/20200811/ga-20.10/boot-initrd.orig
> % cp boot-initrd.fixed /srv/images/groovy/amd64/20200811/ga-20.10/boot-initrd
> % rm -rf ./output; ./tools/jenkins-runner tests/vmtests/test_basic.py:GroovyTestBasic
>
> --
> https://code.launchpad.net/~xnox/cloud-initramfs-tools/+git/cloud-initramfs-tools/+merge/389202
> You are the owner of ~xnox/cloud-initramfs-tools:master.

--
Regards,

Dimitri.

[Scott Moser (smoser)]

'ro' is common on 95% of linux kernel command lines since 1995.

[Dimitri John Ledkov (xnox)]

That's why Dimitri gets to build the OS the bootloader the kernel cmdline
and how it is operated. 😀

I find it weird that everything constantly requests to mount rootfs "ro"
only to ignore it later, and remount rewrite.

"ro" only makes sense without initrd, not with.

And once it was mounted "rw" it makes even less sense to remount it "ro" to
remount "rw" again. Clearly we should be better than that 95% of the time.

On Thu, 13 Aug 2020, 01:43 Scott Moser, <email address hidden> wrote:

> 'ro' is common on 95% of linux kernel command lines since 1995.
>
> --
>
> https://code.launchpad.net/~xnox/cloud-initramfs-tools/+git/cloud-initramfs-tools/+merge/389202
> You are the owner of ~xnox/cloud-initramfs-tools:master.
>

[Scott Moser (smoser)]

I do have to agree that 'ro' is a archaic thing.
but overlayroot is correctly respecting it.

If you want to change kernel command lines, then you can/should do that. But don't *break* overlayroot.

[Dimitri John Ledkov (xnox)]

So, at this point i think rharpers merge is better. It's accurate (reading /proc/mounts) and is more minimal change than this one (thus easier to review/test/validate/land/etc).

Please reject this merge proposal.

review: Disapprove

Unmerged commits

bef4640... by Dimitri John Ledkov on 2020-08-12

Allow booting ephemeral rw overlayroot squashfs without fstab.

 - Do not attempt to overlayrootify non-existing fstab, and mount
 rootfs rw thus removing need to generate any fstab entries; remount
 ro; for systemd to generate mount unit; and remount as rw again.

LP: #1890803

diff --git a/debian/changelog b/debian/changelog
index a9c6a6c..8182b00 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,9 +1,17 @@
 cloud-initramfs-tools (0.45ubuntu1) UNRELEASED; urgency=medium
 
+  [ Scott Moser ]
   * Add dependency on flock for growroot's use of growpart.
     (LP: #1834875)
 
- -- Scott Moser <[e-mail]>  Mon, 24 Feb 2020 20:22:30 -0500
+  [ Dimitri John Ledkov ]
+  * Allow booting ephemeral rw overlayroot squashfs without fstab. LP:
+    #1890803
+    - Do not attempt to overlayrootify non-existing fstab, and mount
+    rootfs rw thus removing need to generate any fstab entries; remount
+    ro; for systemd to generate mount unit; and remount as rw again.
+
+ -- Dimitri John Ledkov <[e-mail]>  Wed, 12 Aug 2020 23:31:07 +0100
 
 cloud-initramfs-tools (0.44ubuntu1) disco; urgency=medium
 
diff --git a/overlayroot/scripts/init-bottom/overlayroot b/overlayroot/scripts/init-bottom/overlayroot
index c13c02b..b926c85 100755
--- a/overlayroot/scripts/init-bottom/overlayroot
+++ b/overlayroot/scripts/init-bottom/overlayroot
@@ -804,10 +804,12 @@ cat <<EOF >${ROOTMNT}/etc/fstab
 EOF
 
 [ $? -eq 0 ] || log_fail "failed to modify /etc/fstab (step 1)"
+if [ -e "${ROOTMNT}${root_ro}/etc/fstab" ]; then
 overlayrootify_fstab "${ROOTMNT}${root_ro}/etc/fstab" "$root_ro" \
 	"$root_rw" "$dir_prefix" "$recurse" "$swap" "${overlayroot_driver}" \
 	>> "${ROOTMNT}/etc/fstab" ||
 	log_fail "failed to modify /etc/fstab (step 2)"
+fi
 
 # we have to make the directories in ${root_rw} because if they do not
 # exist, then the 'upper=' argument to overlayfs will fail.
@@ -820,6 +822,7 @@ if [ "${overlayroot_driver}" = "overlayfs" ]; then
 		log_fail "failed to fix upstart for overlayfs"
 fi
 
+if [ -e "${ROOTMNT}${root_ro}/etc/fstab" ]; then
 # if / is supposed to be mounted read-only (cmdline with 'ro')
 # then mount our overlayfs as read-only just to be more normal
 read cmdline < /proc/cmdline
@@ -829,6 +832,7 @@ if [ "${cmdline#* ro }" != "$cmdline" ]; then
 		log_fail "failed to remount overlayroot read-only"
 	debug "mounted $ROOTMNT read-only per kernel cmdline"
 fi
+fi
 
 msg="configured root with '$overlayroot' using ${overlayroot_driver} per"
 msg="$msg ${used_desc}"