#!/usr/bin/perl -w

=head1 NAME

  xen-create-image - Create a new Xen instance of Debian Sarge.

=head1 SYNOPSIS

  xen-create-image [options]

  Help Options:
   --help     Show this scripts help information.
   --manual   Read this scripts manual.

  Size / General options:
   --size     Set the size of the primary disk image.
   --swap     Set the size of the swap partition.   
   --fs       Specify the filesystem type to use.
   --memory   Setup the amount of memory allocated to the instance.

  Networking options:
   --dhcp      Setup the image to get an IP address via DHCP
   --network   Setup the network the host is upon.
   --gateway   Setup the iamge's network gateway.
   --broadcast Setup the image's network broadcast address.
   --mirror    Setup the mirror to use when installing Sarge.

  Mandatory options:

   --dir       Specify where the output images should go.
   --hostname  Set the images hostname.

=cut



=head1 OPTIONS

=over 8

=item B<--size>  
Specify the size of the virtual images primary drive.  The size may be
suffixed with either Mb, or Gb.

=item B<--swap>
Specify the size of the virtual images swap partition.  The size may be
suffixed with either Mb, or Gb.

=item B<--help>
Show the brief help information.

=item B<--manual>
Read the manual, with examples.

=back

=cut



=head1 EXAMPLE

  The following will create a 2Gb disk image, along with a 128Mb 
 swap file with Debian Sarge setup and running via DHCP.

     xen-create-image --size=2Gb --swap=128Mb --dhcp \
          --dir=/home/xen --hostname=vm01.my.flat


=cut



=head1 DESCRIPTION


  This is a reasonably simple script which is more of a cheap hack
 than a production tool, however it does appear to work nicely for
 my own uses.

  The output of this script will be two files for each new instance:

   1.  One 2Gb file for the installations primary disk image.
   2.  One 128Mb file for the images swap partition.

  Usage:


  The initial two arguments '--hostname' and '--dir' are mandatory,
 and control the hostname and output directory respectively.  Other
 parameters are all network based, either give the list as shown above
 or use the '--dhcp' option to setup the host with a DHCP allocated
 IP address.

  'dir' is used to create the output disk images which are referenced
 in the Xen configuration file.  They will be created as:


   $dir/domains/
   $dir/domains/$hostname/disk.img
   $dir/domains/$hostname/swap.img

  The '/domains/' subdirectory, and sub-subdirectory named after the
 hostname will be created if necessary.

  Basic setup with your hosts file, resolv.conf, etc works just fine.

  The image will also have an OpenSSH server installed upon it, and
 an appropriate /etc/inittab file created.

  You are *strongly* advised to chroot() into the new instance once
 it has been setup to prune the users in the /etc/passwd file which
 will be copied from your hosts system.


=head1 AUTHOR


 Steve
 --
 http://www.steve.org.uk/

 $Id: xen-create-image,v 1.15 2005-12-18 18:38:21 steve Exp $

=cut


=head1 LICENSE

Copyright (c) 2005 by Steve Kemp.  All rights reserved.

This module is free software;
you can redistribute it and/or modify it under
the same terms as Perl itself.
The LICENSE file contains the full text of the license.

=cut


use strict;
use File::Copy;
use File::Temp qw/ tempdir /;
use Getopt::Long;
use Pod::Usage;



#
#  Configuration options.
#
my %CONFIG;


#
# Options set on the command line.
#
my $DIR;        # Mandatory.


#
# Either *all* the relevent networking options must be setup, or
# DHCP must be selected.
#
#
my $MIRROR="http://ftp.us.debian.org/debian"; # set with '--mirror=http://www.etc.com"'



#
# Constants for filesystem usage.
#
my %FILESYSTEM_CREATE;
my %FILESYSTEM_MOUNT;

$FILESYSTEM_CREATE{'ext3'}     = '/sbin/mkfs.ext3 -F ';
$FILESYSTEM_CREATE{'xfs'}      = '/sbin/mkfs.xfs -d name=';
$FILESYSTEM_CREATE{'reiserfs'} = '/sbin/mkfs.reiserfs -f -q ';

$FILESYSTEM_MOUNT{'ext3'}      = '-t ext3';
$FILESYSTEM_MOUNT{'xfs'}       = '-t xfs';
$FILESYSTEM_MOUNT{'reiserfs'}  = '-t reiserfs';



#
#  Setup defaults:
#
#  Memory = 96M, Image = 2000Mb, Swap = 128Mb, and filesystem is ext3.
#
#  These may be overriden by one of the configuration files, or by the
# command line arguments.
#
$CONFIG{'memory'} = '96Mb';
$CONFIG{'size'}   = '2000Mb';
$CONFIG{'swap'}   = '128M';
$CONFIG{'fs'}     = 'ext3';


#
#  Read configuration file(s) if they exist.
#
if ( -e "etc/xen-tools.conf" )
{
    readConfigurationFile( "etc/xen-tools.conf" );
}
if ( -e "/etc/xen-tools/xen-tools.conf" )
{
    readConfigurationFile( "/etc/xen-tools/xen-tools.conf" );
}
if ( -e $ENV{'HOME'} . ".xen-tools.conf" )
{
    readConfigurationFile( $ENV{'HOME'} . ".xen-tools.conf" );
}


#
#  Parse command line arguments, these override the values from the
# configuration file.
#
parseCommandLineArguments();


#
#  Check that the arguments the user has supplied are both 
# valid, and complete.
#
checkArguments();

print "\n";
print "Hostname :  $CONFIG{'hostname'}\n";
print "Image size: $CONFIG{'size'}\n";
print "Swap size:  $CONFIG{'swap'}\n";
print "Fileystem:  $CONFIG{'fs'}\n";

if ( $CONFIG{'dhcp'} ) 
{
    print "DHCP\n";
}
else
{
   $CONFIG{'ip'}        && print "IP       : $CONFIG{'ip'}\n";
   $CONFIG{'network'}   && print "Network  : $CONFIG{'network'}\n";
   $CONFIG{'broadcast'} && print "Broadcast: $CONFIG{'broadcast'}\n";
   $CONFIG{'gateway'}   && print "Gateway  : $CONFIG{'gateway'}\n";
}
print "---\n";

#
#  If the output directories don't exist then create them.
#
if ( ! -d $DIR . "/domains/" )
{
    mkdir $DIR . '/domains', 0777
      || die "Cannot create $DIR/domains - $!";
}
if ( ! -d $DIR . "/domains/" . $CONFIG{'hostname'} )
{
    mkdir $DIR. '/domains/' . $CONFIG{'hostname'}, 0777
      || die "Cannot create $DIR/domains/$CONFIG{'hostname'} - $!" ;
}



#
# The two images we'll use, one for the disk image, one for swap.
#
my $image = $DIR . '/domains/' . $CONFIG{'hostname'} . "/disk.img" ;
my $swap  = $DIR . '/domains/' . $CONFIG{'hostname'} . "/swap.img" ;

#
#  Create swapfile and initialise it.
#
print "Creating swapfile : $swap\n";
$CONFIG{'swap'} =~ s/Mb*$//i;
`/bin/dd if=/dev/zero of=$swap bs=1024k count=$CONFIG{'swap'} >/dev/null 2>/dev/null`;
print "Initializing swap file\n";
`/sbin/mkswap $swap`;
print "Done\n";

#
#  Create disk file and initialise it.
#
print "Creating disk image: $image\n";
$CONFIG{'size'} =~ s/Mb*$/k/i;
`/bin/dd if=/dev/zero of=$image bs=$CONFIG{'size'} count=1 seek=1024 >/dev/null 2>/dev/null`;
print "Creating $CONFIG{'fs'} filesystem\n";

my $create = $FILESYSTEM_CREATE{lc( $CONFIG{'fs'} ) } . $image;
`$create`;
print "Done\n";


#
#  Now mount the image, in a secure temporary location.
#
my $dir = tempdir( CLEANUP => 1 );
my $mount_cmd = "mount " . $FILESYSTEM_MOUNT{lc($CONFIG{'fs'})} . " -o loop $image $dir";
`$mount_cmd`;


# Test that the mount worked

my $mount = `/bin/mount`;

if ( ! $mount =~ /$image/) {
    print "Something went wrong trying to mount the new filesystem\n";
    exit;
}

#
#  Install the base system.
#
print "Running debootstrap to install the system.   This will take a while!\n";
`debootstrap sarge $dir $MIRROR`;
print "Done\n";

#
#  If the debootstrap failed then we'll setup the output directories
# for the configuration files here.
#
`mkdir -p $dir/etc/apt`;
`mkdir -p $dir/etc/network`;

#
#  OK now we can do the basic setup.
#
print "Setting up APT sources .. ";
open( APT, ">", $dir . "/etc/apt/sources.list" );
print APT<<E_O_APT;
#
#  /etc/apt/sources.list
#


# Stable
deb $MIRROR     sarge main contrib non-free

# 
#  Security updates
#
deb     http://security.debian.org/ stable/updates  main contrib non-free


E_O_APT
close( APT );

print "Done\n";



#
#  Copy some files from the host system, after setting up the hostname.
#
#
my @hostFiles = ( "/etc/resolv.conf",
		  "/etc/hosts",
		  "/etc/passwd",
		  "/etc/group",
		  "/etc/shadow",
		  "/etc/gshadow" );

foreach my $file ( @hostFiles )
{
    File::Copy::cp( $file, $dir . "/etc" );
}


#
#  Disable TLS
#
if ( -d $dir . "/lib/tls" ) 
{
    `mv $dir/lib/tls $dir/lib/tls.disabled`;
}



#
#  Now setup the fstab
#
print "Setting up /etc/fstab .. ";
open( TAB, ">", $dir . "/etc/fstab" );
print TAB<<E_O_TAB;
/dev/sda1     /     $CONFIG{'fs'}     errors=remount-ro     0     1
/dev/sda2     none  swap     sw                    0     0
proc          /proc proc     defaults              0     0
E_O_TAB
close( TAB );

print "Done\n";


#
#  Setup the /etc/network/interfaces file upon the guest image
#
setupNetworking( $dir );


#
#  Install OpenSSH
#
installOpenSSH( $dir );

#
#  Fixup Inittab file
#
fixupInittab( $dir );



#
#  Now unmount the image.
#
`umount $dir`;


#
# Finally setup Xen to allow us to create the image.
#
print "Setting up Xen configuration file .. ";
open( XEN, ">", "/etc/xen/$CONFIG{'hostname'}.cfg" );
print XEN<<E_O_XEN;
kernel = "/boot/vmlinuz-2.6.12-xenU"
memory = $CONFIG{'memory'}
name   = "$CONFIG{'hostname'}"
disk   = [ 'file:$image,sda1,w','file:$swap,sda2,w' ]
root   = "/dev/sda1 ro"
E_O_XEN
if ( $CONFIG{'dhcp'} )
{
    print XEN "dhcp=\"dhcp\"\n";
}
else
{
    print XEN "#dhcp=\"dhcp\"\n";
}
close( XEN );

print "Done\n";


#
#  Give status message
#
print <<EOEND;

  To finish the setup of your new host $CONFIG{'hostname'} please run:

    mkdir /mnt/tmp
    mount -t $CONFIG{'fs'} -o loop $image /mnt/tmp

    chroot /mnt/tmp /bin/bash

    # Get security upgrades.
    apt-get upgrade

    # setup passwords, etc.
    passwd root

    # Cleanup.
    exit
    umount /mnt/tmp

 Once completed you may start your new instance of Xen with:

    xm create $CONFIG{'hostname'}.cfg -c

EOEND



=head2 readConfigurationFile

  Read the configuration file specified.

=cut

sub readConfigurationFile
{
    my ($file) = ( @_ );

    open( FILE, "<", $file ) or die "Cannot read file '$file' - $!";

    my $line       = ""; 

    while (defined($line = <FILE>) ) 
    {
        chomp $line;
	if ($line =~ s/\\$//) 
	{
	    $line .= <FILE>;
	    redo unless eof(FILE);
	}
      
	# Skip lines beginning with comments
	next if ( $line =~ /^([ \t]*)\#/ );

	# Skip blank lines
	next if ( length( $line ) < 1 );

	# Strip trailing comments.
	if ( $line =~ /(.*)\#(.*)/ )
	{
	    $line = $1;
	}

	# Find variable settings
	if ( $line =~ /([^=]+)=([^\n]+)/ )
	{
	    my $key = $1;
	    my $val = $2;

	    # Strip leading and trailing whitespace.
	    $key =~ s/^\s+//;
	    $key =~ s/\s+$//;
	    $val =~ s/^\s+//;
	    $val =~ s/\s+$//;
	    
	    # Store value.
	    $CONFIG{ $key } = $val;
	}
    }

    close( FILE );
}




=head2 parseCommandLineArguments

  Parse the arguments specified upon the command line.

=cut

sub parseCommandLineArguments
{
    my $HELP   = 0;
    my $MANUAL = 0;

    #  Parse options.
    #
    GetOptions(
	       "hostname=s", \$CONFIG{'hostname'},
	       "ip=s",       \$CONFIG{'ip'},
	       "gateway=s",  \$CONFIG{'gateway'},
	       "mask=s",     \$CONFIG{'netmask'},
	       "broadcast=s",\$CONFIG{'broadcast'},
	       "network=s",  \$CONFIG{'network'},
	       "dir=s", \$DIR,
	       "dhcp",       \$CONFIG{'dhcp'},
	       "mirror=s", \$MIRROR,
	       "size=s",     \$CONFIG{'size'},
	       "swap=s",     \$CONFIG{'swap'},
	       "memory=s",   \$CONFIG{'memory'},
	       "fs=s",    \$CONFIG{'fs'},
	       "help",    \$HELP,
	       "manual",  \$MANUAL
	      );
    
    pod2usage(1) if $HELP;
    pod2usage(-verbose => 2 ) if $MANUAL;
}



=head2 checkArguments

  Check that the arguments the user has specified are complete and
 make sense.

=cut

sub checkArguments
{

    if (!defined( $CONFIG{'hostname'} ) )
    {
	print<<EOF

  You should set a hostname with '--hostname=foo'.

  This option is required.
EOF
      ;
	exit;
    }


    if (!defined( $DIR ) )
    {
	print<<EOF

  You should set an output directory with '--dir=/my/path'.

  This option is required.  Subdirectories will be created
 beneath the directory you name.

EOF
	  ;
	exit;
    }



    #
    #  Make sure the directory exists.
    #
    if ( ! -d $DIR )
    {
	print "Output directory '$DIR' doesn't exist\n";
	exit;
    }

    # 
    #  Make sure we have a valid size
    #
    if ( !(($CONFIG{'size'} =~ /^\d+[GM]b*$/i) && ($CONFIG{'swap'} =~ /^\d+[GM]b*$/i)) )
    {
        print "Invalid size formats.  Please use something like:\n";
	print " --size=128Mb\n";
	print " --size=2Gb\n";
        exit;
    }


    # Convert Gb -> Mb
    if ( $CONFIG{'size'} =~ /^(\d+)Gb*$/i )
    {
	$CONFIG{'size'} = $1 * 1024 . "M";
    }
    if ( $CONFIG{'swap'} =~ /^(\d+)Gb*$/i )
    {
	$CONFIG{'swap'} = $1 * 1024 . "M";
    }

    # Strip trailing Mb from the memory size.
    if ( $CONFIG{'memory'} =~ /^(\d+)Mb*$/i )
    {
	$CONFIG{'memory'} = $1;
    }


    #    
    #  Check mirror format
    #
    if (!($MIRROR =~ /^http/i)) 
    {
	print "Please enter a valid mirror.\n";
	exit;
    }

    #
    #  Only one of DHCP / IP is required.
    #
    if ( $CONFIG{'ip'} && $CONFIG{'dhcp'})
    {
	print "You've chosen both DHCP and an IP address.\n";
	print "Only one is supported\n";
	exit;
    }

    if ( $CONFIG{'dhcp'} )
    {
	$CONFIG{'gateway'}   = '';
	$CONFIG{'netmask'}   = '';
	$CONFIG{'broadcast'} = '';
	$CONFIG{'ip'}	     = '';
    }

    #
    #  Ensure we know how to create *and* mount the given filesystem.
    #
    if ( !defined( $FILESYSTEM_CREATE{lc( $CONFIG{'fs'} ) } ) ||
	 !defined( $FILESYSTEM_MOUNT{lc( $CONFIG{'fs'} ) } ) )
    {
	print "Unknown filesystem.  Valid choices are:\n";
	foreach my $key (sort keys %FILESYSTEM_MOUNT ) 
	{
	    print "\t" . $key . "\n";
	}
	exit;
    }
}



=head2 setupNetworking

  Setup the /etc/network/interfaces file, and the hostname 
 upon the virtual instance.

=cut

sub setupNetworking
{
    my ( $prefix ) = ( @_ );

    `echo '$CONFIG{'hostname'}' > $prefix/etc/hostname`;

    open( IP, ">", $prefix . "/etc/network/interfaces" );

    if ( $CONFIG{'dhcp'} )
    {
	print IP<<E_O_DHCP;
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback
	    
# The primary network interface
auto eth0
iface eth0 inet dhcp

E_O_DHCP
    }
    else
    {
	print IP<<E_O_STATIC_IP;
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback
	    
# The primary network interface
auto eth0
iface eth0 inet static
 address $CONFIG{'ip'}
 gateway $CONFIG{'gateway'}
 netmask $CONFIG{'netmask'}
 network $CONFIG{'network'}
 broadcast $CONFIG{'broadcast'}

E_O_STATIC_IP
    }

    close( IP );
}



=head2 installOpenSSH

  Install OpenSSH upon the virtual instance via apt-get.

=cut

sub installOpenSSH
{
    my ( $prefix ) = ( @_ );

    `chroot $prefix /usr/bin/apt-get update`;
    `DEBIAN_FRONTEND=noninteractive chroot $prefix /usr/bin/apt-get --yes --force-yes install ssh`;
    `chroot $prefix /etc/init.d/ssh stop`;
}



=head2 fixupInittab

  Copy the host systems /etc/inittab to the virtual installation 
 making a couple of minor changes:

  1. Setup the first console to be "Linux".
  2. Disable all virtual consoles.

=cut 

sub fixupInittab
{
    my ( $prefix ) = ( @_ );


    my @init;
    open( INITTAB, "<", "/etc/inittab" );
    foreach my $line ( <INITTAB> )
    {
	chomp $line;
	if ( $line =~ /:respawn:/ )
	{
	    if ( $line =~ /^1/ )
	    {
		$line = "s0:12345:respawn:/sbin/getty 115200 ttyS0 linux"
	    }
	    else
	    {
		$line = "#" . $line;
	    }
	}
	push @init, $line;
    }
    close( INITTAB );
    
    
    open( OUTPUT, ">", "$prefix/etc/inittab" );
    foreach my $line ( @init )
    {
	print OUTPUT $line . "\n";
    }
    close( OUTPUT )
}