Skip to content

Instantly share code, notes, and snippets.

@jaybuff

jaybuff/LVM.pm

Created November 2, 2010 01:07
Show Gist options
  • Save jaybuff/659138 to your computer and use it in GitHub Desktop.
Save jaybuff/659138 to your computer and use it in GitHub Desktop.
Download ZIP
When I first started Joot I used LVM rather than QCOW for backing files.
Raw
LVM.pm
package Joot;
use strict;
use warnings;
use IPC::Cmd;
use LWP::Simple;
use Log::Log4perl qw(:easy);
use YAML::Tiny;
sub new {
my $proto = shift;
my $class = ref($proto) || $proto;
my $args = shift || {};
# initialize logging if it's not already
my $level = $args->{verbose} ? $DEBUG : $INFO;
if ( Log::Log4perl->initialized() ) {
get_logger()->level($level);
}
else {
Log::Log4perl->easy_init($level);
}
$IPC::Cmd::VERBOSE = $args->{verbose};
# determine which config file we're going to read in
if ( !$args->{config_file} || !-r $args->{config_file} ) {
$args->{config_file} = ( -r "$ENV{HOME}/.joot" ) ? "$ENV{HOME}/.joot" : "/etc/joot.cfg";
}
my $self = bless $args, $class;
$self->{joot_home} = $self->config("joot_home", "/var/joot");
$self->create_joot_vg();
return $self;
}
# return false if there is not JOOT volume group
# otherwise, return the directory that contains joot_disk
sub get_current_joot_home {
my $self = shift;
# return if we've already setup the JOOT volume group
my $pvs_out = $self->run( _bin('sudo'), _bin('pvs'), '-o', 'pv_name,vg_name', '--noheadings' );
foreach ( split "\n", $pvs_out ) {
# /dev/loop0 JOOT
m/(\S+)\s+(\S+)/;
my $pv_name = $1;
my $vg_name = $2;
if ( $vg_name && $vg_name eq "JOOT" ) {
my $lo_out = $self->run( _bin('sudo'), _bin('losetup'), $pv_name );
# /dev/loop0: [0802]:14548994 (/mnt/joot/joot_disk)
$lo_out =~ m#\((.*?)/joot_disk\)#;
return $1;
}
}
# return false; JOOT volume doesn't exist yet
return;
}
# verify that the joot vg has been correctly initialized
# if this is the first time we've has been run, we'll set everything up
sub create_joot_vg {
my $self = shift;
my $joot_home = $self->{joot_home};
DEBUG("initializing $joot_home");
die "joot_home $joot_home doesn't exist\n" if ( !-d $joot_home );
# return if we're already initialized
if ( my $current_home = $self->get_current_joot_home() ) {
if ( $current_home ne $joot_home ) {
die "JOOT volume already exists at $current_home; can't move to $joot_home\n. Try \"joot --purgeall\"";
}
return;
}
my $disk = "$joot_home/joot_disk";
DEBUG("creating JOOT volume group backed by $disk");
# create a 1 terabyte sparse file which will be our block based LVM volume
# TODO how did we settle on 1T for size of disk?
$self->run( _bin("sudo"), _bin("dd"), "if=/dev/zero", "of=$disk", qw(bs=1 count=1 seek=1T) );
# create loop back device
$self->run( _bin("sudo"), _bin("losetup"), '-f', "$disk" );
# determine the path of the loop back device we just created
my $losetup_out = $self->run( _bin("sudo"), _bin("losetup"), '-j', "$disk" );
$losetup_out =~ m#^([^:]+):#;
my $lo_dev = $1;
# create the joot volume based on that device
if ( !$lo_dev || !-b $lo_dev ) {
die "\"losetup -j $disk\" didn't return a block device\n";
}
$self->run( _bin("sudo"), _bin("vgcreate"), 'JOOT', "$lo_dev" );
}
sub _bin {
my $prog = shift;
# use this search path. die if $prog isn't in one of these dirs
my @paths = qw(/bin /sbin /usr/bin /usr/sbin /usr/local/bin /usr/local/sbin);
foreach my $path ( @paths ) {
if ( -x "$path/$prog" ) {
return "$path/$prog";
}
}
die "couldn't find $prog in " . join( ":", @paths);
}
sub run {
my $self = shift;
my @args = @_;
my $cmd = join( " ", @args );
my ( $success, $err, $full_buf, $stdout_buf, $stderr_buf ) = IPC::Cmd::run( command => \@args );
if ( !$success ) {
FATAL "Error executing $cmd";
if ($full_buf) {
FATAL join( "", @{$full_buf} );
}
die "$err\n";
}
return join( "", @{$stdout_buf} );
}
# two ways to call config:
# my $cfg = $self->config();
# print "foo setting is " . $cfg->{foo};
# or
# print "foo setting is " . $self->config( "foo", "foo_default" );
# default is optional (will die if setting is missing)
sub config {
my $self = shift;
my $field = shift;
my $default = shift;
# read in the config file, parse it and store it in the object
# only do this once
if ( !$self->{config} ) {
DEBUG("Reading config file " . $self->{config_file} );
$self->{config} = YAML::Tiny::LoadFile( $self->{config_file} );
}
# if the user requests a field, send back the value (or the default)
# otherwise, give them the whole hash reference
if ( defined $field ) {
if ( exists $self->{config}->{$field} ) {
return $self->{config}->{$field};
}
elsif ( defined $default ) {
return $default;
}
else {
die "Config file is missing required setting \"$field\"\n";
}
}
return $self->{config};
}
sub chroot {
my $self = shift;
my $joot_name = shift || die "missing joot name to chroot into\n";
die "not implemented";
}
sub install_image {
my $self = shift;
my $image_url = shift;
my $image_name = shift;
my $images = $self->images();
if ( $images->{$image_name} ) {
WARN "tried to install an image that is already installed";
return;
}
# TODO fetch image and untar it into $tmpfile
# should I use curl (progress meter is nice) or LWP::Simple (part of perl base)
my $tmpfile = "/tmp/lucid.tar";
my $joot_home = $self->{joot_home};
DEBUG("creating and mounting a logic volume to install $image_name into");
# XXX how big?
$self->run( _bin("sudo"), _bin("lvcreate"), qw(-L 1G -n), "image_$image_name", "JOOT" );
$self->run( _bin("sudo"), _bin("mkfs.ext3"), "/dev/JOOT/image_$image_name" );
$self->run( _bin("sudo"), _bin("mkdir"), "-p", "$joot_home/images/$image_name" );
$self->run( _bin("sudo"), _bin("mount"), "/dev/JOOT/image_$image_name", "$joot_home/images/$image_name" );
$self->run( _bin("sudo"), _bin("tar"), "xf", $tmpfile, "-C", "$joot_home/images/$image_name" );
$self->run( _bin("sudo"), _bin("umount"), "/dev/JOOT/image_$image_name" );
#TODO resize the lv to a bit larger than the space it takes?
#XXX
#unlink $tmpfile;
}
sub create {
my $self = shift;
my $joot_name = shift or die "missing joot name to create\n";
my $image_name = shift;
my $joots = $self->list();
if ( $joots->{$joot_name} ) {
die "$joot_name already exists.\n";
}
#TODO default image name
die "missing image name for create" if !$image_name;
my $images = $self->images();
if ( !exists $images->{$image_name} ) {
die "\"$image_name\" is an invalid image name\n";
}
# download and install it if it's not already installed
if ( !$images->{$image_name} ) {
# TODO
$self->install_image( "XXX", "Ubuntu-10.04" );
}
DEBUG "snapshotting lvm logical volume to create a new joot";
my $joot_home = $self->{joot_home};
# TODO make the default size configurable
$self->run( _bin("sudo"), _bin("lvcreate"), qw(-s -n), "joot_$joot_name", qw(-L 1G), "/dev/JOOT/image_$image_name" );
$self->run( _bin("sudo"), _bin("mkdir"), "-p", "$joot_home/joots/$joot_name" );
$self->run( _bin("sudo"), _bin("mount"), "/dev/JOOT/joot_$joot_name", "$joot_home/joots/$joot_name" );
}
sub images {
my $self = shift;
my $lvs = $self->lvs();
return $lvs->{image};
}
sub list {
my $self = shift;
my $lvs = $self->lvs();
return $lvs->{joot};
}
# inspect all the LVs in the JOOT volume group
# return all installed images and joots in a hash
sub lvs {
my $self = shift;
my $lv = {
joot => {},
image => {},
};
my $lvs_out = $self->run( _bin('sudo'), _bin('lvs'), qw(JOOT --noheadings -o lv_name) );
foreach ( split "\n", $lvs_out ) {
m/\s*(joot|image)_(\S+)/;
my $type = $1 or die "invalid lvs command output\n";
my $name = $2 or die "invalid lvs command output\n";
$lv->{$type}->{$name} = 1;
}
return $lv;
}
sub delete {
my $self = shift;
my $joot_name = shift || die "missing joot name to delete\n";
die "delete not implemented";
}
sub rename {
my $self = shift;
my $old_name = shift || die "rename: missing old name\n";
my $new_name = shift || die "rename: missing new name\n";
die "rename not implemented";
}
# delete the joot volume group and the disk that backed it
sub purgeall {
my $self = shift;
# confirm the user really wants to do this
my $current_home = $self->get_current_joot_home();
print "WARNING: this will destroy all joots installed at $current_home. Are you sure? ";
while ( <STDIN> ) {
last if $_ eq "yes\n";
print "type \"yes\" to purge all data. Ctrl+C otherwise.\n";
}
$self->run(_bin("sudo"), _bin("vgremove"), "JOOT" );
my $lo_out = $self->run( _bin('sudo'), _bin('losetup'), "-j", "$current_home/joot_disk" );
foreach ( split "\n", $lo_out ) {
m/\s*([^:]+):/;
my $dev = $1;
$self->run( _bin('sudo'), _bin('losetup'), "-d", $dev );
}
$self->run( _bin('sudo'), _bin('rm'), "$current_home/joot_disk" );
}
1;
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment