Merge pull request #865 from SUSE/ramdisk_deployment

Support ramdisk deployment in OEM images

doc/source/building/build_oem_disk.rst

@@ -1,3 +1,5 @@
+.. _oem:
+
 Build an OEM Expandable Disk Image
 ==================================
 

doc/source/building/working_with_images.rst

@@ -18,3 +18,4 @@ different image types.
    working_with_images/uninstall_package_requests 
    working_with_images/vagrant_setup
    working_with_images/pxe_live_iso_boot
+   working_with_images/oem_ramdisk_deployment

doc/source/building/working_with_images/oem_ramdisk_deployment.rst

@@ -0,0 +1,86 @@
+.. _ramdisk_deployment:
+
+Deploy and Run System in a RamDisk
+==================================
+
+.. sidebar:: Abstract
+
+   This page provides further information for handling
+   oem images built with KIWI and references the following
+   articles:
+
+   * :ref:`oem`
+
+If a machine should run the OS completely in memory without
+the need for any persistent storage, the approach to deploy
+the image into a ramdisk serves this purpose. KIWI allows
+to create a bootable ISO image which deploys the image
+into a ramdisk and activates that image with the following
+oem type definition:
+
+.. code:: xml
+
+    <type image="oem" filesystem="ext4" installiso="true" bootloader="grub2" initrd_system="dracut" installboot="install" boottimeout="1" kernelcmdline="rd.kiwi.ramdisk ramdisk_size=2048000">
+        <oemconfig>
+            <oem-skip-verify>true</oem-skip-verify>
+            <oem-unattended>true</oem-unattended>
+            <oem-unattended-id>/dev/ram1</oem-unattended-id>
+            <oem-swap>false</oem-swap>
+            <oem-multipath-scan>false</oem-multipath-scan>
+         </oemconfig>
+     </type>
+
+The type specification above builds an installation ISO image
+which deploys the System Image into the specified ramdisk
+device (/dev/ram1). The setup of the ISO image boots with a
+short boot timeout of 1sec and just runs through the process
+without asking any questions. In a ramdisk deployment the
+optional target verification, swap space and multipath targets
+are out of scope and therefore disabled.
+
+The configured size of the ramdisk specifies the size of the
+OS disk and must be at least of the size of the System Image.
+The disk size can be configured with the following value in
+the kernelcmdline attribute:
+
+*  ramdisk_size=kbyte-value"
+
+An image built with the above setup can be tested in QEMU as
+follows:
+
+.. code:: bash
+
+    $ qemu -cdrom LimeJeOS-Leap-42.3.x86_64-1.42.3.install.iso
+
+.. note:: Enough Main Memory
+
+    The machine, no matter if it's a virtual machine like QEMU
+    or a real machine, must provide enough RAM to hold the image
+    in the ramdisk as well as have enough RAM available to operate
+    the OS and its applications. The KIWI build image with the
+    extension .raw provides the System Image which gets deployed
+    into the RAM space. Substract the size of the System Image
+    from the RAM space the machine offers and make sure the result
+    is still big enough for the use case of the appliance. In
+    case of a virtual machine, attach enough main memory to fit
+    this calculation. In case of QEMU this can be done with
+    the `-m` option
+
+Like all other oem KIWI images, also the ramdisk setup supports
+all the deployments methods as explained in :ref:`deployment_methods`
+This means it's also possible to dump the ISO image on a USB
+stick let the system boot from it and unplug the stick from
+the machine because the system was deployed into RAM
+
+.. note:: Limitations Of RamDisk Deployments
+
+    Only standard images which can be booted by a simple root mount
+    and root switch can be used. Usually KIWI calls kexec after deployment
+    such that the correct, for the image created dracut initrd, will boot
+    the image. In case of a RAM only system kexec does not work because
+    it would loose the ramdisk contents. Thus the dracut initrd driving
+    the deployment is also the environment to boot the system.
+    There are cases where this environment is not suitable to boot
+    the system. One example would be luks encrypted images which requires
+    to run unlock code inside of the initrd which is not present in the
+    initrd created for deployment.

dracut/modules.d/90kiwi-dump/kiwi-dump-image.sh

@@ -36,14 +36,29 @@ function get_disk_list {
     local disk_meta
     local item_status=on
     local list_items
+    local blk_opts
     if [ ! -z "${kiwi_devicepersistency}" ];then
         disk_id=${kiwi_devicepersistency}
     fi
-    if [ ! -z "${kiwi_oemmultipath_scan}" ];then
+    if getargbool 0 rd.kiwi.ramdisk; then
+        # target should be a ramdisk on request. Thus actively
+        # load the ramdisk block driver and support custom sizes
+        local rd_size
+        local modfile=/etc/modprobe.d/99-brd.conf
+        rd_size=$(getarg ramdisk_size=)
+        if [ ! -z "${rd_size}" ];then
+            echo "options brd rd_size=${rd_size}" > ${modfile}
+        fi
+        modprobe brd
+        udev_pending
+        # target should be a ramdisk on request. Thus instruct
+        # lsblk to list only ramdisk devices (Major=1)
+        blk_opts="-I 1"
+    elif [ ! -z "${kiwi_oemmultipath_scan}" ];then
         scan_multipath_devices
     fi
     for disk_meta in $(
-        lsblk -p -n -r -o NAME,SIZE,TYPE | grep disk | tr ' ' ":"
+        lsblk "${blk_opts}" -p -n -r -o NAME,SIZE,TYPE | grep disk | tr ' ' ":"
     );do
         disk_device="$(echo "${disk_meta}" | cut -f1 -d:)"
         if [ "$(blkid "${disk_device}" -s LABEL -o value)" = \
@@ -373,6 +388,14 @@ fi
 
 check_image_integrity "${image_target}"
 
-boot_installed_system
-
-exit 0
+if getargbool 0 rd.kiwi.ramdisk; then
+    # For ramdisk deployment a kexec boot is not possible as it
+    # will wipe the contents of the ramdisk. Therefore we prepare
+    # the switch_root from this deployment initrd. Also see the
+    # unit generator: dracut-kiwi-ramdisk-generator
+    kpartx -s -a "${image_target}"
+else
+    # Standard deployment will use kexec to activate and boot the
+    # deployed system
+    boot_installed_system
+fi

dracut/modules.d/90kiwi-dump/kiwi-ramdisk-deployment-generator.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+
+type getarg >/dev/null 2>&1 || . /lib/dracut-lib.sh
+
+GENERATOR_DIR="$1"
+[ -z "${GENERATOR_DIR}" ] && exit 1
+[ -d "${GENERATOR_DIR}" ] || mkdir -p "${GENERATOR_DIR}"
+
+root_uuid=$(
+    while read -r -d ' ' opt; do echo "${opt}";done < /config.bootoptions |\
+    grep root= | cut -f2- -d=
+)
+
+{
+    echo "[Unit]"
+    echo "Before=initrd-root-fs.target"
+    echo "[Mount]"
+    echo "Where=/sysroot"
+    echo "What=${root_uuid}"
+    _dev=RamDisk_rootfs
+} > "$GENERATOR_DIR"/sysroot.mount
+
+if [ ! -e "$GENERATOR_DIR/initrd-root-fs.target.requires/sysroot.mount" ]; then
+    mkdir -p "$GENERATOR_DIR"/initrd-root-fs.target.requires
+    ln -s "$GENERATOR_DIR"/sysroot.mount \
+        "$GENERATOR_DIR"/initrd-root-fs.target.requires/sysroot.mount
+fi
+
+mkdir -p "$GENERATOR_DIR/$_dev.device.d"
+{
+    echo "[Unit]"
+    echo "JobTimeoutSec=60"
+} > "$GENERATOR_DIR/$_dev.device.d/timeout.conf"

dracut/modules.d/90kiwi-dump/module-setup.sh

@@ -14,8 +14,9 @@ installkernel() {
 # called by dracut
 install() {
     declare moddir=${moddir}
+    declare systemdutildir=${systemdutildir}
     inst_multiple \
-        tr lsblk dd md5sum head pv kexec basename awk
+        tr lsblk dd md5sum head pv kexec basename awk kpartx
 
     inst_hook pre-udev 30 "${moddir}/kiwi-installer-genrules.sh"
     inst_hook pre-udev 60 "${moddir}/kiwi-dump-net-genrules.sh"
@@ -25,6 +26,10 @@ install() {
 
     inst_hook cmdline 30 "${moddir}/parse-kiwi-install.sh"
     inst_hook pre-mount 30 "${moddir}/kiwi-dump-image.sh"
+
+    inst_script "${moddir}/kiwi-ramdisk-deployment-generator.sh" \
+        "${systemdutildir}/system-generators/dracut-kiwi-ramdisk-generator"
+
     inst_rules 60-cdrom_id.rules
     dracut_need_initqueue
 }