overlay.d: abort booting if system has more than 1 'boot' partition

Inspired by: coreos/fedora-coreos-tracker#976

Signed-off-by: Nikita Dubrovskii <[email protected]>

overlay.d/05core/usr/lib/dracut/modules.d/35coreos-ignition/coreos-ensure-single-partition.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+# checks and aborts the boot if system has several partitions with label specified by $1
+
+set -euo pipefail
+
+PARTITIONS=()
+mapfile -t PARTITIONS < <(lsblk -o LABEL,NAME --pairs --paths --noheadings | grep "LABEL=\""$1"\"")
+
+LENGTH=${#PARTITIONS[@]}
+if [[ ${LENGTH} -gt 1 ]]; then
+    echo "System has "${LENGTH}" partitions with '"$1"' label:"
+    for PT in "${PARTITIONS[@]}"; do
+        echo "${PT}"
+    done
+    echo "Please 'wipefs' other partitions/disks and reboot. Aborting..."
+    exit 1
+fi

overlay.d/05core/usr/lib/dracut/modules.d/35coreos-ignition/coreos-gpt-setup.service

@@ -33,4 +33,5 @@ OnFailureJobMode=isolate
 [Service]
 Type=oneshot
 RemainAfterExit=yes
+ExecStartPre=/usr/sbin/coreos-ensure-single-partition boot
 ExecStart=/usr/sbin/coreos-gpt-setup /dev/disk/by-label/boot

overlay.d/05core/usr/lib/dracut/modules.d/35coreos-ignition/module-setup.sh

@@ -30,6 +30,9 @@ install() {
     inst_script "$moddir/coreos-gpt-setup.sh" \
         "/usr/sbin/coreos-gpt-setup"
 
+    inst_script "$moddir/coreos-ensure-single-partition.sh" \
+        "/usr/sbin/coreos-ensure-single-partition"
+
     inst_script "$moddir/coreos-ignition-setup-user.sh" \
         "/usr/sbin/coreos-ignition-setup-user"