All that glitters

Makefile

TARGET_HOSTNAME=golden
TEMPLATE=template
RELEASE=squeeze
PROXY=http://lsip.4a.telent.net:3142
MIRROR=$(PROXY)/ftp.debian.org/debian

# this must be in a format that works as input to sfdisk
PARTITIONS='1,1044,L,*\n1045,243\n1288,\n;'

all: checkuid0 disk.img

checkuid0:
        [ `id -u` = 0 ] 

root:
        test -d root1 || mkdir root1
        debootstrap --variant=minbase --include=aptitude,linux-image-2.6-amd64,net-tools,isc-dhcp-client,make,rsync,netcat-traditional $(RELEASE) root1 $(MIRROR)
        mv root1 root


define FIRSTTIMEBOOT
#!/bin/sh
set -e
PATH=/usr/sbin:/sbin:/bin:/usr/bin
dhclient eth0
ifconfig lo 127.0.0.1 up
( echo "GET /" | nc $$(echo $(PROXY)| awk -F/ '{sub(":"," ",$$3);print $$3}')  ) && QEMU=1
export QEMU
test -f /firstboot-mkfs.sh && . /firstboot-mkfs.sh
make -C /usr/local/master sync
test -f /firstboot-postinstall.sh && . /firstboot-postinstall.sh
endef
export FIRSTTIMEBOOT
firstboot.sh: Makefile
        @echo "$$FIRSTTIMEBOOT" >$@
        chmod +x $@

define EXTLINUXCONF
DEFAULT linux
LABEL linux
  KERNEL /vmlinuz
  APPEND ro root=/dev/sda1 initrd=/initrd.img
endef
export  EXTLINUXCONF
extlinux.conf: Makefile
        @echo "$$EXTLINUXCONF" >$@

root/firstboot-mkfs.sh: firstboot-mkfs.sh
        cp $< $@

root/firstboot-postinstall.sh: firstboot-postinstall.sh
        cp $< $@


root/firstboot.sh: root root/firstboot-mkfs.sh root/firstboot-postinstall.sh firstboot.sh $(shell find $(TEMPLATE)/ -type f )
        -rm -rf root/usr/local/master
        mkdir -p root/usr/local/master
        git gc
        (find .git && git ls-files) | \
            cpio -p --make-directories  root/usr/local/master
        echo '127.0.0.1 localhost' > root/etc/hosts
        echo $(TARGET_HOSTNAME) >root/etc/hostname
        -rm root/etc/udev/rules.d/70-persistent-net.rules
        cp firstboot.sh $@
        # this needs to exist at package installation time
        touch root/etc/default/roles
        echo 'test -x /firstboot.sh && sh /firstboot.sh && chmod 444 /firstboot.sh' > root/etc/rc.local

# qemu ignores the CHS settings in a disk image and assumes a geometry of
# 255 heads, 63 sectors per track.  For more on this see
#  http://ww.telent.net/2009/6/3/migrating_xen_to_kvm
BYTES_IN_CYLINDER=$(shell expr 63 \* 255 \* 512)

disk.img: root/firstboot.sh extlinux.conf Makefile
        cp /usr/lib/syslinux/mbr.bin qemudisk.raw
        dd if=/dev/zero of=qemudisk.raw bs=$(BYTES_IN_CYLINDER) seek=3134 count=1
        echo $(PARTITIONS)  | sfdisk qemudisk.raw
        sfdisk -A1  qemudisk.raw
        kpartx -a qemudisk.raw 
        kpartx -l qemudisk.raw > partitions.dat
        mkfs.ext4 -L root /dev/mapper/`awk < partitions.dat '/loop[0-9]+p1/ {print $$1}'`
        test -d mnt || mkdir mnt
        mount qemudisk.raw mnt -t ext4 -o loop,offset=$(BYTES_IN_CYLINDER) 
        tar -C root -cf - . | tar -C mnt -xpvf -
        extlinux --install mnt
        cp extlinux.conf mnt
        umount mnt
        kpartx -d  qemudisk.raw 
        mv  qemudisk.raw disk.img

kvm: disk.img
        # Vary these params according to your needs
        # The live server we seek to emulate has 2+GB and two ethernet cards.
        # Our postgres config doesn't even startup unless it can get a shm
        # segment exceeding 1GB 
        kvm -hda disk.img  -m 2048  -k en-gb -net nic,model=e1000 -net  tap,ifname=tap0,script=no -net nic,model=e1000 -net  tap,ifname=tap1,script=no

clean:
        -umount mnt
        -rmdir mnt
        -kpartx -d  qemudisk.raw        
        -rm -rf root disk.img qemudisk.raw firsttimeboot.sh partitions.dat extlinux.conf

# these commands are run natively on a live host, either on first
# boot to install all the config and packages, or at a later date to 
# synchronise them with the versions supposed to be installed

ifdef QEMU
  AP=-o Acquire::http::Proxy="$(PROXY)"
else
  AP=
endif

sync: 
        rsync -av --exclude \*~ --exclude ./Makefile `pwd`/$(TEMPLATE)/ /
        (cd /home ; for i in * ; do chown -R $$i $$i ;done )
        for i in `seq 10 250` ; do echo "10.0.0.$$i host$$i" ;done >$@ >/etc/more_hosts
        insserv $(shell for i in $(TEMPLATE)/etc/init.d/*; do basename $$i  ;done)
        aptitude $(AP) -y update
        /sbin/restore-package-versions.sh $(TEMPLATE)/etc/installed-packages.list
        debconf-set-selections $(TEMPLATE)/etc/debconf-selections.list
        aptitude $(AP) -y  -o Dpkg::Options::="--force-confdef" install 

show-upgraded:
        /sbin/save-package-versions.sh installed-packages.list
        debconf-get-selections > debconf-selections.list
        diff -u installed-packages.list $(TEMPLATE)/etc/installed-packages.list ||true
        diff -u debconf-selections.list $(TEMPLATE)/etc/debconf-selections.list ||true

save-upgraded:
        cp installed-packages.list $(TEMPLATE)/etc/installed-packages.list
        cp  debconf-selections.list $(TEMPLATE)/etc/debconf-selections.list

A souped-up and rather more generalised version of this is now available at https://github.com/telent/goldleaf