diskimage-builder/elements/dracut-ramdisk/post-install.d/99-build-dracut-ramdisk

#!/bin/bash

set -eux
set -o pipefail

_LIB="/tmp/ramdisk-build"

source "$_LIB/common-defaults"
source "$_LIB/img-defaults"
source "$_LIB/ramdisk-defaults"

source "$_LIB/common-functions"
source "$_LIB/img-functions"
source "$_LIB/ramdisk-functions"

KERNEL_VERSION="${DIB_KERNEL_VERSION:-$(find_kernel_version)}"
MODULE_DIR="$MODULE_ROOT/lib/modules/$KERNEL_VERSION"
FIRMWARE_DIR="$MODULE_ROOT/lib/firmware"
LIB_UDEV="$LIB_UDEV_ROOT/lib/udev"
INIT="$_LIB/scripts/init"
FUNCTIONS_D="$_LIB/scripts/d"
MODULE="$_LIB/scripts/module"
# NOTE(bnemec): IMAGE_ELEMENT is normally set in disk-image-create, but we're
# not using that to build the image here.
IMAGE_ELEMENT=

mk_build_dir
mkdir -p "$TMP_BUILD_DIR/mnt"
export TMP_HOOKS_PATH=/tmp
export TMP_MOUNT_PATH="$TMP_BUILD_DIR/mnt"

echo "building ramdisk in $TMP_MOUNT_PATH"

populate_init
SCRIPT_HOME=/tmp/in_target.d/bin TMP_HOOKS_PATH=/tmp/in_target.d run_d ramdisk-install
MODULE_PATH="/usr/lib/dracut/modules.d"
cp -r "$MODULE" "$MODULE_PATH/80deploy-ramdisk"
cp "$TMP_MOUNT_PATH/init" "$MODULE_PATH/80deploy-ramdisk/init.sh"

# Notes on the options passed to Dracut:
# -N: Do not build a host-specific ramdisk.  We want to be able to run this ramdisk
#     on as many different machines as possible.
# --install: A list of the binaries needed by our ramdisk script fragments.
# --kernel-cmdline: Kernel parameters to pass to the ramdisk.  rd.neednet is required
#                   to force Dracut to bring up networking even if it isn't passed a
#                   network target root.  Pre-loading the ahci module is necessary
#                   on some systems to ensure that SATA disks are recognized.
# --include: Files from the chroot to include in the ramdisk.
# --kver: The kernel version to use, as determined above.
# --add-drivers: Extra kernel modules to include in the ramdisk.
# -o: Force omission of these dracut modules.  Our scripts are written for bash,
#     so dash is not desirable, and plymouth was causing some issues on Ubuntu.
dracut -N \
    --install "$(cat /etc/dib_binary_deps)" \
    --kernel-cmdline "rd.shell rd.debug rd.neednet=1 rd.driver.pre=ahci" \
    --include "$TMP_MOUNT_PATH/init-func" /init-func \
    --kver "${KERNEL_VERSION}" \
    --add-drivers "virtio virtio_net virtio_blk" \
    -o "dash plymouth" \
    /tmp/ramdisk

cp "/boot/vmlinuz-${KERNEL_VERSION}" /tmp/kernel
chmod o+r /tmp/kernel
# We don't want to run cleanup (set in mk_build_dir above) when this exits
trap EXIT