Generate symlinks from install section in units

hooks/095-preset-all.chroot

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+set -eux
+
+systemctl preset-all
+systemctl --global preset-all

hooks/100-systemd-in-lib.chroot

@@ -3,7 +3,32 @@
 set -eux
 
 echo "ensure the systemd target.wants are in /lib instead of /etc"
-for d in multi-user.target.wants sysinit.target.wants timers.target.wants; do
-    mv etc/systemd/system/"$d"/* lib/systemd/system/"$d"
-done
 
+for path in /etc/systemd/system/*.wants /etc/systemd/system/*.requires; do
+    if ! [ -d "${path}" ]; then
+        continue
+    fi
+    want="$(basename "${path}")"
+    for link in "${path}"/*; do
+        if ! [ -L "${link}" ]; then
+            continue
+        fi
+        mkdir -p /lib/systemd/system/"${want}"
+        source="$(basename "${link}")"
+        unitpath="$(realpath "${link}")"
+        case "${unitpath}" in
+            /lib/systemd/system/*)
+                ln -rs "${unitpath}" "/lib/systemd/system/${want}/${source}"
+                ;;
+            /usr/lib/systemd/system/*)
+                ln -rs "${unitpath}" "/usr/lib/systemd/system/${want}/${source}"
+                ;;
+            *)
+                ln -s "${unitpath}" "/lib/systemd/system/${want}/${source}"
+                ;;
+        esac
+        rm "${link}"
+    done
+
+    rmdir "${path}"
+done

static/usr/lib/systemd/system-preset/90-ubuntu-core.preset

@@ -0,0 +1,8 @@
+enable core.start-snapd.service
+enable keep-entangled-mounts.target
+enable plymouth-show-install.service
+enable remount-data.service
+enable remount-seed.service
+enable snapd.seeded.service
+enable snapd.sshd-keygen.service
+enable swapfile.service

static/usr/lib/systemd/system/keep-entangled-mounts.target

@@ -5,3 +5,6 @@ Wants=run-mnt-data.mount
 Wants=run-mnt-ubuntu\x2dseed.mount
 Wants=usr-lib-modules.mount
 Wants=run-mnt-kernel.mount
+
+[Install]
+WantedBy=shutdown.target

static/usr/lib/systemd/system/remount-data.service

@@ -8,3 +8,6 @@ Before=shutdown.target
 [Service]
 Type=oneshot
 ExecStart=/bin/mount -o remount,ro /run/mnt/data
+
+[Install]
+WantedBy=shutdown.target

static/usr/lib/systemd/system/remount-seed.service

@@ -8,3 +8,6 @@ Before=shutdown.target
 [Service]
 Type=oneshot
 ExecStart=/bin/mount -o remount,ro /run/mnt/ubuntu-seed
+
+[Install]
+WantedBy=shutdown.target

static/usr/lib/systemd/system/snapd.sshd-keygen.service

@@ -6,3 +6,6 @@ Before=sshd.service
 Type=oneshot
 RemainAfterExit=yes
 ExecStart=/usr/bin/core-sshd-host-keygen
+
+[Install]
+WantedBy=multi-user.target

static/usr/lib/systemd/system/var-lib-snapd-save.mount

@@ -6,3 +6,6 @@ What=/run/mnt/ubuntu-save
 Where=/var/lib/snapd/save
 Options=bind
 Type=none
+
+[Install]
+WantedBy=local-fs.target