Makefile: T2640: add helper to convert ISO to OCI image to start a container

Use either "make oci" or call the script manually:

$ scripts/iso-to-oci build/live-image-amd64.hybrid.iso

I: mount ISO build/live-image-amd64.hybrid.iso
I: extracting squashfs content
I: generate OCI container image vyos-1.5-strongswan-202311241125.tar
I: to import the previously generated OCI image to your local images run:

   docker import vyos-1.5-strongswan-202311241125.tar vyos:1.5-strongswan-202311241125 --change 'CMD [/sbin/init]'

3 files changed, 69 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index 36643800..23101b27 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,4 @@ packages/*
 !packages/*/
 testinstall*.img
 *.qcow2
+*.tar
diff --git a/Makefile b/Makefile
index f9b5903f..393ef3b7 100644
--- a/Makefile
+++ b/Makefile
@@ -59,6 +59,11 @@ testraid: checkiso
 qemu-live: checkiso
 	scripts/check-qemu-install --qemu-cmd build/live-image-amd64.hybrid.iso
 
+.PHONE: oci
+.ONESHELL:
+oci: checkiso
+	scripts/iso-to-oci build/live-image-amd64.hybrid.iso
+
 .PHONY: clean
 .ONESHELL:
 clean:
diff --git a/scripts/iso-to-oci b/scripts/iso-to-oci
new file mode 100755
index 00000000..c9396290
--- /dev/null
+++ b/scripts/iso-to-oci
@@ -0,0 +1,63 @@
+#!/bin/bash
+
+function cleanup() {
+    if [[ -d $ROOTFS ]]; then
+        rm -rf $ROOTFS
+    fi
+    if [[ -d $UNSQUASHFS ]]; then
+        rm -rf $UNSQUASHFS
+    fi
+}
+
+if [[ $(/usr/bin/id -u) -ne 0 ]]; then
+    echo "Not running as root"
+    exit
+fi
+
+if [ "$#" -ne 1 ]; then
+    echo "Illegal number of parameters"
+fi
+
+ISO=$1
+ROOTFS=rootfs
+UNSQUASHFS=unsquashfs
+
+# ensure clean working directory
+cleanup
+
+mkdir $ROOTFS $UNSQUASHFS
+echo "I: mount ISO $ISO"
+mount -t iso9660 -o loop $ISO $ROOTFS/ >/dev/null 2>&1
+
+# create directory, unpack squashfs filesystem, get ISO version
+# and unmount ISO
+echo "I: extracting squashfs content"
+unsquashfs -follow -dest $UNSQUASHFS/ $ROOTFS/live/filesystem.squashfs >/dev/null 2>&1
+VERSION=$(jq --raw-output .version $ROOTFS/version.json)
+umount $ROOTFS/
+
+# fix locales for correct system configuration loading
+sed -i 's/^LANG=.*$/LANG=C.UTF-8/' $UNSQUASHFS/etc/default/locale
+
+# optional step: Decrease docker image size by deleting not necessary files for container
+rm -rf $UNSQUASHFS/boot/*.img
+rm -rf $UNSQUASHFS/boot/*vyos*
+rm -rf $UNSQUASHFS/boot/vmlinuz
+rm -rf $UNSQUASHFS/lib/firmware/
+rm -rf $UNSQUASHFS/usr/lib/x86_64-linux-gnu/libwireshark.so*
+rm -rf $UNSQUASHFS/lib/modules/*amd64-vyos
+rm -rf $UNSQUASHFS/root/.gnupg
+
+# create a symbolic link to the configuration
+ln -s /opt/vyatta/etc/config $UNSQUASHFS/config
+
+# create docker image
+echo "I: generate OCI container image vyos-$VERSION.tar"
+tar -C unsquashfs -c . -f vyos-$VERSION.tar
+
+echo "I: to import the previously generated OCI image to your local images run:"
+echo ""
+echo "   docker import vyos-$VERSION.tar vyos:$VERSION --change 'CMD ["/sbin/init"]'"
+echo ""
+
+cleanup