alpine-overlay/kubezero/zdt-base/boot.sh

#!/bin/sh
# We have no metadata nor instance parameters yet!

# We built on top of tiny-cloud
. /lib/tiny-cloud/common

# archive orig /var, mount new var on top and restore orig var
copy_and_mount() {
  local dev=$1

  tar cf /tmp/var.tar /var 2>/dev/null
  mount -t xfs -o noatime "$dev" /var
  tar xf /tmp/var.tar -C / && rm -f /tmp/var.tar
}

setup_var() {
  local _devices="$(find /dev/xvd[a-z] /dev/sd[a-z] -maxdepth 0 2>/dev/null || true)"

  for d in $_devices; do
    # resolve to a valid block device
    dev="$(realpath "$d")"
    [ -b "$dev" ] || continue

    # already mounted
    mount | grep -q "$d" && continue

    case "$CLOUD" in
      aws)
        # on AWS look for sdx/xvdx
        if [ "$d" = "/dev/sdx" -o "$d" = "/dev/xvdx" ]; then
          # check volume for existing filesystem
          type=$(file -Lbs $d)
          if [[ "$type" =~ "XFS filesystem" ]]; then
            xfs_repair $d >/dev/null 2>&1
            mount -t xfs -o noatime "$d" /var
          else
            mkfs.xfs -qf $d >/dev/null
            copy_and_mount "$d"
          fi

          add_once /etc/fstab "$d /var xfs defaults,noatime,nofail 0 2"

          log -i -t early info "mounted $d at /var"
        fi
        ;;
      nocloud)
        # Todo: should we try to mount a special tagged block device as /var ?
        return 0
        ;;
      *)
        ewarn "Unsupported cloud: $CLOUD"
        return 1
        ;;
    esac
  done
}