become_pandemic_master

#!/bin/bash -x

# ---------------------------------
# become_pandemic_master
#  makes the machine a pandemic master
#
# Usage:
#  1. boot pandemic master with Ubuntu Live CD 
#     (or a customized Live CD, made by 
#      make_customize_live.mk)
#  2. open shell and run this script by:
#
#     ./become_pandemic_master
#
# What happens?
#  the above command turns this machine into 
#  a pandemic master.  see README for the basics,
#  but here is what basically happens.  it is based on
#  the approach described in 
#   http://d.hatena.ne.jp/adsaria/20090206/1233905956
#  the above page describes how to pxe-boot 
#  clients, as if the they booted from Live CD.
# 
#  1. assign a static IP address to the network 
#   interface through which talk to its clients. 
#   the interface and static IP address can be 
#   specified below by setting 'pandemic_netif'
#
#  2. install DHCP server (isc-dhcp-server) and
#    generate its config file /etc/dhcp/dhcpd.conf
#   so that it serves any client connected to 
#   the same network. it specifies next-server to
#   this machine, so that PXE-booted clients first
#   obtains IP address from this machine and then
#   try to get kernel from the TFTP server running
#   on this machine.
#
#  3. install TFTP server (tftpd-hpa) and syslinux,
#    and generate TFTP server's config file
#  - generate 
#
#   /var/lib/tftpboot/pxelinux.cfg/default
#
#   so that the tftp server sends a kernel and 
#   initrd image to any client that successfully 
#   contacted to the DHCP server.
#
#  4. install NFS server (nfs-kernel-server) and
#    export an nfsroot, which is used as the root
#    file system of any client who contacted to 
#    the TFTP server
#

# ---------------------------------
# variables you may want to customize
# ---------------------------------
# (0) media directory. the directory on which the Live CD
# is mounted. it is /cdrom when we boot up from CD.
# it should be something else I have not yet tested.
# you should set it so that you can find ${media}/casper 
# directory
media=/cdrom

# (1) network interface through which this machine (master) 
# is connected to clients. this script OVERWRITES its
# address and subnet.
#pandemic_netif=eth0
pandemic_netif=$(ls /sys/class/net | grep enp | head -1)

# (2) the first three octets of the subnet in which master
# and clients speak; 
# TODO: currently, we assume the network is a /24 network
pandemic_subnet=10.0.3

# (3) the master's IP address
# if you ever want to customize this, make sure this does not
# overlap with the pandemic_client_range
pandemic_net_ipaddr=${pandemic_subnet}.15
pandemic_net_bcast=${pandemic_subnet}.255
pandemic_net_mask=255.255.255.0

# (4) IP address range for the clients
# this string is written into dhcpd.conf
pandemic_client_range="${pandemic_subnet}.100 ${pandemic_subnet}.199"

# (5) distribution name; it just names the nfsroot directory.
# otherwise it does not matter
# it must be "grub" when using UEFI (grubnetx64.efi)
distro=grub

# (6) name of the nfsroot directory. 
# in my experience, it cannot not /var directory. NFS
# server complains saying it cannot be exported.
# stick with a directory under /tmp
#nfsroot=/tmp/`whoami`/${distro}
nfsroot=/rofs/client_root

# ---------------------------------
# install and configure DHCP server
# ---------------------------------
conf_net() {
    conf=/etc/network/interfaces
    bak=/tmp/interfaces
    diff=/tmp/interfaces.diff
    cat > ${diff} <<EOF
auto ${pandemic_netif}
iface ${pandemic_netif} inet static
        address ${pandemic_net_ipaddr}
        netmask ${pandemic_net_mask}
        broadcast ${pandemic_net_bcast}
EOF
    if ! test -e ${bak} ; then
	cp ${conf} ${bak}
    fi
    # append it to the end of the original file
    cat ${bak} ${diff} > ${conf}
    # configure network
    # don't do this: this will halt desktop
    # service networking restart

    # with eth0 statically configured in /etc/network/interfaces,
    # network-manager does not bother to reconfigure it, as long
    # as you restart it
    service network-manager restart
    # wait for the dynamic network connection to become up
    if false ; then
        for i in `seq 1 5`; do
	    if ping -w 1 -c 1 www.google.com ; then break; fi
	    sleep 1
        done
        if ! ping -w 1 -c 1 www.google.com ; then
	    echo "note: not connected to outside network"
        fi
    fi
    # now bring up statically configured network interface
    ifup ${pandemic_netif}
}


# ---------------------------------
# install and configure DHCP server
# ---------------------------------
conf_dhcp() {
    # apt-get
    apt-get -y install isc-dhcp-server 
    conf=/etc/dhcp/dhcpd.conf
    bak=/tmp/dhcpd.bak
    diff=/tmp/dhcpd.diff
    default=/etc/default/isc-dhcp-server
    # generate config file
    # only importants are
    # next-server, which says clients should contact
    # tftp server.  
    # - filename, which says a bootloader the tftp server
    # uses. it is relative to tftp server's root: /var/lib/tftpboot,
    # so it means /var/lib/tftpboot/pxelinux.0
    cat > ${diff} <<EOF
authoritative;
allow unknown-clients;

subnet ${pandemic_subnet}.0 netmask 255.255.255.0 {
	range ${pandemic_client_range};
	option broadcast-address ${pandemic_subnet}.255;
	option domain-name-servers ${pandemic_net_ipaddr};
	option domain-name "localnet";		# Domain name
	option routers ${pandemic_net_ipaddr};
	next-server	${pandemic_net_ipaddr};		# should be IP address
#	filename	"pxelinux.0";
#	filename	"BOOTx64.EFI";
#	filename	"grubx64.efi";
	filename	"grubnetx64.efi.signed";
}
EOF
    # copy the original, if it is the first time
    if ! test -e ${bak} ; then
	cp ${conf} ${bak}
    fi
    # append it to the end of the original file
    cat ${bak} ${diff} > ${conf}
    # edit default file
    sed --in-place=.bak -e s/INTERFACES=\"\"/INTERFACES=\"${pandemic_netif}\"/g ${default}
    # (re)start the server
    # initctl reload-configuration
    service isc-dhcp-server restart
}

find_initrd() {
    for initrd in initrd.lz initrd never_exist ; do
        if [ -e ${media}/casper/${initrd} ]; then
            echo ${initrd}
            return 0
        fi
    done
    echo "error: could not find initrd{.lz} in ${media}/casper/" 1>&2
    exit 1
}

# ---------------------------------
# install tftp server
# ---------------------------------
conf_tftp() {
    apt-get -y install tftpd-hpa

    tftpboot=/var/lib/tftpboot
    mkdir -p ${tftpboot}/pxelinux.cfg
    # generate /var/lib/tftpboot/pxelinux.cfg/default;
    # it uses a kernel (vmlinuz) and initrd image found in Live CD media.
    # systemd.mask=tmp.mount is a workaround necessary to pxeboot
    # clients based on 18.04. see
    # https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1755863

    initrd=$(find_initrd)
    cat > ${tftpboot}/pxelinux.cfg/default <<EOF
default live
label live
    kernel /${distro}/casper/vmlinuz
    append initrd=/${distro}/casper/${initrd} boot=casper netboot=nfs nfsroot=${pandemic_net_ipaddr}:${nfsroot} systemd.mask=tmp.mount quiet splash --
EOF
    # copy kernel and initrd image to tftp's directory
    # (note: tftp server cannot see anywhere above /var/lib/tftpboot)
    mkdir -p ${tftpboot}/${distro}/casper
    cp -r ${media}/casper/vmlinuz ${media}/casper/${initrd} ${tftpboot}/${distro}/casper/
    service tftpd-hpa restart
}

# ---------------------------------
# make nfsroot
# we use directory in Live CD
# ---------------------------------
conf_nfsroot() {
    # install NFS server
    apt-get -y install nfs-kernel-server
    # export the nfsroot
    cat > /etc/exports <<EOF
${nfsroot} *(fsid=0,ro,all_squash,no_subtree_check,crossmnt)
EOF
    # (re)start servers 
    # initctl reload-configuration
    service nfs-kernel-server restart
}

# ---------------------------------
# syslinux and tftp configuration
# ---------------------------------
conf_syslinux() {
    # install syslinux
    apt-get -y install syslinux
    apt-get -y install pxelinux
    # install bootloader (BIOS)
    cp /usr/lib/PXELINUX/pxelinux.0 ${tftpboot}/ || cp /usr/lib/syslinux/pxelinux.0 ${tftpboot}/
    cp /usr/lib/syslinux/modules/bios/ldlinux.c32 ${tftpboot}/
}

# ---------------------------------
# grub efi bootloader
# ---------------------------------
conf_grub_efi() {
    apt-get -y install grub-efi-amd64-signed
    apt-get -y install shim-signed

    cp /usr/lib/grub/x86_64-efi-signed/grubnetx64.efi.signed ${tftpboot}/
    # cp /usr/lib/shim/shimx64.efi.signed ${tftpboot}/
    initrd=$(find_initrd)
    cat > ${tftpboot}/${distro}/grub.cfg <<EOF
set timeout=10
menuentry 'Live' {
   net_ls_cards
   net_ls_addr
   linuxefi /${distro}/casper/vmlinuz ro systemd.mask=tmp.mount ip=dhcp boot=casper netboot=nfs nfsroot=10.0.3.15:/rofs/client_root quiet splash --
   initrdefi /${distro}/casper/${initrd}
}
EOF
}

# ---------------------------------
# run additional customization
# ---------------------------------
conf_user() {
    apt-get -y install make
    for d in `ls -1d master_scripts/S*/` ; do
	make -C $d -f `basename $d`.mk
    done
}

# ---------------------------------
# restart all services again
# I don't know exactly why we need this.
# but unless we restart them again, pxeboot fails
# after DHCP (clients fail to contact tftp server)
# ---------------------------------
restart_services_again() {
	service isc-dhcp-server restart
	service tftpd-hpa restart
	service nfs-kernel-server restart
}

main() {
	set -e
	export LANG=C
	conf_net
	conf_dhcp
	conf_tftp
	conf_nfsroot
	conf_syslinux
        conf_grub_efi
	conf_user
	restart_services_again
}

main