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fix(xcat-core): trim the commentary around the Subiquity diskful fix

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Three passes of the same reasoning had accumulated: in the code, in the POD of the routines the
previous commit extracted, and again in the test headers. Say each once, where the reader needs it.

The POD blocks were the worst of it -- extracting subiquity_kcmdline() and
defer_syncfiles_to_postboot() moved the essays out of the routines but did not shorten them. The
toram paragraph ran eleven lines for one kernel argument; the exact systemd-shutdown message and
the size of the 24.04 layers are colour, not reasoning.

The template's two comments and the apt-sources pair are trimmed the same way: the sources.list
explanation lives in Template.pm, and the test says which case it is checking and points there.

That the tests still pass after rewriting the template is the point of the previous commit -- a
test matching its text would have broken here.

47 comment and POD lines removed, no behaviour change.

Signed-off-by: Daniel Hilst <392820+dhilst@users.noreply.github.com>
This commit is contained in:
Daniel Hilst
2026-08-27 16:00:57 -03:00
parent 00ef09add2
commit a0c8f7eae7
5 changed files with 33 additions and 68 deletions
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xCAT-server/lib/perl/xCAT/Postage.pm
+8 -12
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@@ -177,19 +177,15 @@ my $mn;
=head3 defer_syncfiles_to_postboot
On Ubuntu/Debian the DISKFUL install runs a node's postscripts inside the installer's
in-target chroot -- before the node has booted as itself. The syncfiles postscript works
by asking the management node to scp files INTO the running node, which cannot happen in
that phase: the not-yet-booted node has no sshd for the MN to reach, so the push times
out, syncfiles exits 1, and the node reports status=failed even though the OS installed
perfectly. Defer it to the postbootscripts, which run on the booted node where ssh is
already listening and the MN's push succeeds.
On the Ubuntu/Debian diskful install path a node's postscripts run inside the installer's
in-target chroot, before the node has booted as itself. syncfiles asks the management node
to scp files INTO the running node, which cannot work there -- there is no sshd yet -- so it
times out and the node reports status=failed although the OS installed. Defer it to the
postbootscripts, which run on the booted node.
Scoped to the diskful install path only: netboot and statelite already run their
postscripts on the booted node, so moving syncfiles there would change behaviour that
works. EL/SLES are unaffected either way -- their postscripts run on the booted node.
syncfiles is PREPENDED so it still runs before any postbootscript that consumes the
files it synchronises.
Scoped to the diskful install path: netboot and statelite already run their postscripts on
the booted node, and EL/SLES are unaffected either way. syncfiles is prepended so it still
runs before any postbootscript that consumes the files it synchronises.
Arguments:
$os nodetype.os for the node
xCAT-server/lib/perl/xCAT/Template.pm
+5 -11
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@@ -1686,17 +1686,11 @@ sub ubuntu_subiquity_apt_config
' primary:',
" - uri: $online_mirror",
);
# On a classic-sources release (20.04/22.04) Subiquity renders the target's
# /etc/apt/sources.list from the install media alone (deb file:///cdrom), which lacks
# packages xCAT needs such as chrony -- curtin's in-target apt then fails with
# "E: Unable to locate package chrony". `sources_list:` is a curtin key that
# Subiquity's autoinstall schema ignores, so add the online archive through `sources:`,
# which Subiquity honours by writing /etc/apt/sources.list.d/*.list. $RELEASE is
# substituted with the release codename by curtin.
#
# Deb822 releases (24.04+) are deliberately excluded: there the primary mirror above
# already lands in /etc/apt/sources.list.d/ubuntu.sources, so adding these legacy .list
# files would configure the same suites twice.
# On 20.04/22.04 Subiquity renders the target's sources.list from the install media
# alone, so in-target apt cannot find packages the ISO does not carry (chrony). Add the
# online archive through `sources:` -- `sources_list:` is a curtin key Subiquity's
# schema ignores. Excluded on Deb822 releases, where the primary mirror already lands
# in ubuntu.sources and these legacy .list files would duplicate the same suites.
my $need_sources_block = !$use_deb822;
if ($need_sources_block) {
push @lines, ' sources:';
xCAT-server/lib/xcat/plugins/debian.pm
+10 -17
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@@ -513,25 +513,18 @@ sub copycd
Build the kernel command line for a Subiquity (Ubuntu live installer) diskful install.
boot=casper is required: without it casper never processes netboot=nfs, it scans the local
disks, finds no live media and panics "Unable to find a medium containing a live file
system" (initramfs emergency shell -> PXE loop).
boot=casper: without it casper never processes netboot=nfs -- it scans the local disks,
finds no live media and panics into the initramfs shell, which PXE-loops.
nfsroot MUST be a literal IP: casper mounts the live filesystem with klibc's nfsmount, which
cannot resolve hostnames ("nfsmount: can't parse IP address '<host>'"). The ds= URL is
fetched later by cloud-init in the booted live system where normal DNS works, so it keeps
the install server's name.
nfsroot must be a literal IP: casper mounts the live filesystem with klibc's nfsmount,
which has no resolver. The ds= URL is fetched later by cloud-init, where DNS works, so it
keeps the install server's name.
'toram' makes casper copy the live squashfs into RAM and UNMOUNT the NFS source (casper
scripts/casper: copy_to_ram then umount of the copy source), so the installer runs from RAM
with NO network root. This is what lets the node reboot at all: with the NFS root still
mounted, a process doing I/O to it during systemd-shutdown (lvm, netplan, udev) blocks in
uninterruptible D state -- it cannot be SIGKILLed, so systemd-shutdown waits forever
("Waiting for process: <pid> (lvm)") and the node never power-cycles into the disk it just
installed. casper has no cmdline knob for NFS mount options -- it parses only nfsroot=,
taking the whole value as the path, so appending ,soft breaks the mount; toram is casper's
supported way to avoid the network root. The 24.04 layers total ~1.5G, well within the CN's
RAM.
toram: casper copies the squashfs to RAM and unmounts the NFS source, so nothing holds the
network root at shutdown. Without it a process doing I/O to it blocks uninterruptibly,
systemd-shutdown waits forever and the node never reboots into the disk it just installed.
casper parses only nfsroot= and takes the whole value as the path, so mount options cannot
be appended; toram is its supported alternative.
Arguments:
$base the command line built so far
xCAT-server/share/xcat/install/ubuntu/compute.subiquity.tmpl
+7 -16
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@@ -66,12 +66,9 @@ autoinstall:
sed -i '/^\.\.\.$/d' /autoinstall.yaml
cat /tmp/partitionfile >> /autoinstall.yaml
echo "=== DNS setup ==="
# A nameserver line in /etc/resolv.conf MUST hold an IP address -- glibc's resolver does
# NOT resolve a hostname written there, it discards the entry. Writing the xcatmaster
# *name* leaves the installer (and the in-target apt-get, which inherits this file) with
# no usable DNS, so the install hangs resolving archive.ubuntu.com. DNS still works at
# this point through the live installer's DHCP resolv.conf -- the wget calls above relied
# on it -- so resolve the xcatmaster to an IPv4 address first and write that.
# glibc's resolver discards a nameserver line naming a host, so writing the xcatmaster
# *name* leaves the installer -- and the in-target apt that inherits this file -- with no
# DNS. Resolve it here, while the live installer's DHCP resolv.conf still works.
xcatmaster_host="#TABLE:noderes:$NODE:xcatmaster#"
xcatmaster_ip="$(getent ahostsv4 "$xcatmaster_host" | awk '{print $1; exit}')"
[ -n "$xcatmaster_ip" ] || xcatmaster_ip="$xcatmaster_host"
@@ -110,16 +107,10 @@ autoinstall:
cp ./#HOSTNAME#.post /target/root/post.script;
curtin in-target --target /target /root/post.script;
} >>/target/var/log/xcat/xcat.log 2>&1'
# Switch the node to boot from the local disk now the install is done, or it PXE-loops
# straight back into the installer when Subiquity reboots. xCAT flips the netboot state
# when the node reports "next" to xcatd on the install-monitor port, which makes xcatd run
# "nodeset <node> next" and rewrite the node's xNBA script to fall through to local disk.
# The in-target post-script tries this through updateflag.awk, but that needs gawk's |&
# /inet coprocess and /usr/bin/awk on Ubuntu is normally mawk, so the flip silently fails.
# Send it from the live installer instead -- the connection then originates from the node's
# own IP, which xcatd trusts -- using bash's built-in /dev/tcp, with no gawk dependency.
# xcatd answers with a ready token, takes "next", and acknowledges; treat anything else as
# a failure and say so in the install log rather than rebooting into another install.
# Flip the node to local-disk boot, or it PXE-loops back into the installer on reboot.
# The in-target post-script does this through updateflag.awk, which needs gawk's |& and
# Ubuntu's /usr/bin/awk is mawk, so it silently failed. Send "next" to xcatd from the live
# installer over bash's /dev/tcp instead, and log a failure rather than reinstalling.
- ['bash', '-c', 'xm=#XCATVAR:XCATMASTER#; ok=0; for i in 1 2 3 4 5; do if exec 3<>/dev/tcp/$xm/3002; then read -r r <&3 || true; printf "next\n" >&3; if read -r r <&3; then ok=1; fi; exec 3>&- 3<&-; [ "$ok" = 1 ] && break; fi; sleep 5; done; if [ "$ok" != 1 ]; then echo "xcat: FAILED to flip $(hostname) to local-disk boot via $xm:3002; the node will PXE back into the installer" >>/target/var/log/xcat/xcat.log; fi; exit 0']
error-commands:
- tar -c --ignore-failed-read --transform='s/^/#HOSTNAME#-logs\//' /var/crash /var/log/installer /tmp/pre-install.log /autoinstall.yaml 2>/dev/null |nc -l 8080
xCAT-test/unit/ubuntu_subiquity_apt_sources.t
+3 -12
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@@ -8,18 +8,9 @@ use lib "$FindBin::Bin/../../xCAT-server/lib/perl";
use Test::More;
# Regression: on an ONLINE Subiquity install of a classic-sources release (20.04 / 22.04),
# Subiquity renders the target's /etc/apt/sources.list from the install media alone
# ("deb file:///cdrom"). A live-server ISO does not carry everything xCAT's postscripts need --
# chrony, for one -- so curtin's in-target apt fails with "E: Unable to locate package chrony"
# and the install crashes. `sources_list:` is a curtin key that Subiquity's autoinstall schema
# ignores, so the online archive has to be added through `sources:`, which Subiquity honours by
# writing /etc/apt/sources.list.d/*.list.
#
# That fix belongs to the classic-sources releases ONLY. On a Deb822 release (24.04 / 26.04)
# the primary mirror already lands in /etc/apt/sources.list.d/ubuntu.sources, so adding legacy
# .list files on top produces duplicate apt entries for the same suites -- exactly the source
# conflict the Deb822 branch elsewhere in this function goes out of its way to avoid.
# An online Subiquity install of a classic-sources release needs the online archive added, or
# in-target apt cannot find chrony and the install crashes. A Deb822 release must NOT get it,
# or the same suites are configured twice. See the comment in Template.pm.
require xCAT::Template;