From 87262e4f915c03596547d63159d2c30ac459beeb Mon Sep 17 00:00:00 2001
From: Jeremi Piotrowski <jpiotrowski@microsoft.com>
Date: Mon, 11 Mar 2024 09:41:01 +0000
Subject: [PATCH] build_library: Add mangle script for zfs sysext

There are two challenges with the sysext: it needs config files in /etc
and it needs udev rules for mounting during boot to work. The etc files
are placed in the standard flatcar etc overlay path but the overlay is
mounted from the initrd. So instead, we create a tmpfiles.d rule that
symlinks the best important files over. For the udev issue, we create a
drop-in in /etc that ensures udev runs after systemd-sysext.

We also can't rely on systemd presets to work, so instead parse the
preset file and statically create the service dependencies. For the
primary zfs.target we rely on an Upholds entry. Users can still disabled
unwanted services if they want.

We also removed unnecessary files:
- development files
- initramfs related scripts

Signed-off-by: Jeremi Piotrowski <jpiotrowski@microsoft.com>
---
 build_library/sysext_mangle_flatcar-zfs | 43 +++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100755 build_library/sysext_mangle_flatcar-zfs

diff --git a/build_library/sysext_mangle_flatcar-zfs b/build_library/sysext_mangle_flatcar-zfs
new file mode 100755
index 0000000000..13e9135b3c
--- /dev/null
+++ b/build_library/sysext_mangle_flatcar-zfs
@@ -0,0 +1,43 @@
+#!/bin/bash
+
+set -euo pipefail
+rootfs="${1}"
+
+pushd "${rootfs}"
+
+rm -rf ./usr/{lib/debug/,lib64/cmake/,include/}
+rm -rf ./usr/lib/dracut/
+rm -rf ./usr/share/initramfs-tools
+rm -rf ./usr/src
+
+mkdir -p ./usr/share/zfs/etc
+rm -rf ./etc/{csh.env,environment.d/,profile.env}
+cp -a ./etc/. ./usr/share/zfs/etc/
+
+pushd ./usr/lib/systemd/system
+while read cmd unit; do
+  if [ "$cmd" = enable ]; then
+    target=$(awk -F= '/WantedBy/ { print $2 }' $unit)
+    mkdir -p "${target}.wants"
+    ln -svr "${unit}" "${target}".wants/
+  fi
+done < <(grep -v '^#' "${rootfs}"/usr/lib/systemd/system-preset/50-zfs.preset)
+mkdir -p "multi-user.target.d"
+{ echo "[Unit]"; echo "Upholds=zfs.target"; } > "multi-user.target.d/10-zfs.conf"
+popd
+
+mkdir -p ./usr/lib/tmpfiles.d
+cat <<EOF >./usr/lib/tmpfiles.d/10-zfs.conf
+d  /etc/zfs                                                 0755  root  root  -  -
+L  /etc/zfs/zed.d                                           -     -     -     -  /usr/share/zfs/etc/zfs/zed.d
+L  /etc/zfs/zfs-functions                                   -     -     -     -  /usr/share/zfs/etc/zfs/zfs-functions
+L  /etc/zfs/zpool.d                                         -     -     -     -  /usr/share/zfs/etc/zfs/zpool.d
+C  /etc/systemd/system/systemd-udevd.service.d/10-zfs.conf  -     -     -     -  /usr/lib/systemd/system/systemd-udevd.service.d/10-zfs.conf
+EOF
+
+mkdir -p ./usr/lib/systemd/system/systemd-udevd.service.d
+cat <<EOF >./usr/lib/systemd/system/systemd-udevd.service.d/10-zfs.conf
+[Unit]
+After=systemd-sysext.service
+EOF
+popd