Adding iso-scan feature to kiwi-live dracut module

[davidcassany]

This commit adds the iso-scan scripts to kiwi-live module_setup
if the former files are found in the system inside the dmsquash-live
dracut module directory.

Fixes #574 and is related to #521

[davidcassany]

With this change is it possible to boot from an iso (regardless of using flags="overlay" or flags="dmsquash") with a grub2 menu entry like this:

menuentry 'Live openSUSE' --class suse --class gnu-linux --class gnu --class os {
        set isolabel=CDROM
        set isofile="/boot/iso/LimeJeOS-tumbleweed.x86_64-1.99.1.iso"
        loopback loop $isofile
        linux (loop)/boot/x86_64/loader/linux boot=isolinux iso-scan/filename=$isofile root=live:CDLABEL=$isolabel ro rd.live.image rhgb
        initrd (loop)/boot/x86_64/loader/initrd
}

Also managed to boot from a vfat usb using the live-fat-stick command and adjusting syslinux bootloader config afterwards:

host:~> sudo live-fat-stick LimeJeOS-tumbleweed.x86_64-1.99.1.iso /dev/sdc1

Where /dev/sdc1 is the vfat partition of the USB stick. Later I updated the <usbmountpoint>/boot/syslinux/syslinux.cfg file to include the iso-scan/filename=/LimeJeOS-tumbleweed.x86_64-1.99.1.iso root=live:CDLABEL=CDROM parameters to the append line, something like:

LABEL LimeJeOS-tumbleweed.x86_64-1.99.1.iso
        kernel linux-LimeJeOS-tumbleweed.x86_64-1.99.1.iso
        append initrd=initrd-LimeJeOS-tumbleweed.x86_64-1.99.1.iso isofrom=/dev/disk/by-uuid/5E0C-AA8A:/LimeJeOS-tumbleweed.x86_64-1.99.1.iso isofrom_device=/dev/disk/by-uuid/5E0C-AA8A isofrom_system=/LimeJeOS-tumbleweed.x86_64-1.99.1.iso loader=syslinux splash=silent   quiet showopts iso-scan/filename=/LimeJeOS-tumbleweed.x86_64-1.99.1.iso root=live:CDLABEL=CDROM 

About #521 I am not sure that much more can be done from KIWI perspective, as moving the ISO to a vfat stick and set the bootloader and other parameters is out if the scope of KIWI, but there is the great live-fat-stick tool for that matter.

Persistent COW files are not part of this PR and I believe it should be handled in another PR in order to facilitate reviewing and tests.

[schaefi]

This is great and again we participate from what dracut already provides :)

Regarding live-fat-stick I think it would be worth mentioning in the documentation

[davidcassany]

Yes, I was afraid that iso-scan scripts would be somehow coupled with dmsquash-live module, but it turned out that it is pretty simple and atomic.

Sure, live-fat-stick should be mentioned in the documentation, this is true.

[cyberorg]

There is https://software.opensuse.org/package/live-grub-stick using grub2(works with all partitions supported by grub2) instead of syslinux(only vfat), and https://software.opensuse.org/package/live-usb-gui script that act as gui frontend to both those scripts.

[cyberorg]

Tried with http://widehat.opensuse.org/tumbleweed/iso/openSUSE-Tumbleweed-Rescue-CD-x86_64-Snapshot20180129-Media.iso get just dracut shell, there is no /var/log/boot.kiwi, what should I be looking for to check if this patch is included in the initrd?

[davidcassany]

@cyberorg In order to see if the patch is included you should check the dracut modules version, as I can see the patch should be in any dracut-kiwi-live package equal or higher than v9.12.0. You can check the installed version from the packages file produced by kiwi.

Also you can check /usr/lib/dracut/modules.d/90kiwi-live/module_setup.sh script from the dracut shell, there should be something like that:

dmsquashdir=$(find "${dracutbasedir}/modules.d" -name "*dmsquash-live")     
if [ -n "${dmsquashdir}" ] && \                                             
    [ -f "${dmsquashdir}/parse-iso-scan.sh" ] && \                          
    [ -f "${dmsquashdir}/iso-scan.sh" ]; then                               
    inst_hook cmdline 31 "${dmsquashdir}/parse-iso-scan.sh"                 
    inst_script "${dmsquashdir}/iso-scan.sh" "/sbin/iso-scan"               
fi

This is the patch I did to include iso-scan.sh script, which basically looks for the iso in devices and loop mounts it. If this part is there then the patch is included into the iso.

[cyberorg]

Works, tested using images here: https://build.opensuse.org/project/show/openSUSE:Factory:Live

Thanks