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Sugar ought to be easy to run from chroots. For a variety of silly reasons, this isn't yet the case, but it might be soon. Ping [[User:Mstone|Michael]] with questions.
=== Status ===


=== Chroot Construction ===
* sugar-chroot-0.1 released: see [http://dev.laptop.org/git/users/mstone/sugar-chroot sugar-chroot]


There are lots of ways to create appropriate chroots; e.g. by hand, with debootstrap, with mock, etc.
=== Purpose ===


With debootstrap, in order to get a working chroot, you want something like:
''You want to hack sugar. You don't want to fuss around. '''You want sugar-chroot.'''''


  export CHROOT=`pwd`/sid-root
=== Usage ===
  debootstrap --arch i386 sid $CHROOT http://debian.lcs.mit.edu/debian
  sudo chroot $CHROOT /bin/bash -l
  # and some of the following:
  mount -t proc proc $CHROOT/proc
  mount -t devpts devpts $CHROOT/dev/pts
  mount -t selinuxfs selinux $CHROOT/selinux


As excerpted from the '''[http://dev.laptop.org/git/users/mstone/sugar-chroot/plain/README README]''':


With mock, it would be more like:
sugar-chroot consists of simple scripts. Download and unpack them like so:


  mock -r fedora-devel-i386 --init
NV=sugar-chroot-0.1
  mock -r fedora-devel-i386 --shell
curl http://dev.laptop.org/~mstone/releases/SOURCES/$NV.tar.xz | tar Zxf $NV.tar.xz
cd $NV


=== X11 ===
To use them, pick a supported distro:


Most X11 servers are configured to disable TCP connections. This means that in order to get a working X connection we can:
DISTRO=debian
DISTRO=fedora


# bind-mount the X unix socket into the chroot.
To configure:
# ssh ''into'' the chroot with X11-forwarding enabled.
# enable TCP on an X server, e.g. a nested Xephyr.


We're going to try option (3) first:
echo $DISTRO > conf/distro
$EDITOR conf/$DISTRO.mk


  Xephyr -ac :1
Then run


::''NB: If you figure out how to make Xephyr bind only to localhost sockets (or how to make it use a custom xauth config), speak up!''
sudo make r/distro
 
and, inside the chroot:


  export DISPLAY=localhost:1
to install your chroot.


=== D-Bus ===
=== History ===


Sugar wants to be able to use global state stored in both HAL and NetworkManager, both of which live on the system bus. Consequently, we need to bind-mount
See http://wiki.sugarlabs.org/index.php?title=Development_Team/Chroot&oldid=36911 for the manual instructions which sugar-chroot automates.
 
  mount --bind /var/run/dbus $CHROOT/var/run/dbus
 
before entering the chroot. (Mock uses unshare() to enter a new mount-point namespace since this makes garbage collection of mountpoints much easier.)
 
=== User Account ===
 
For stupid reasons, it's necessary that Sugar run under a uid inside the chroot which exists as a real account outside the chroot. (Talk to the DBus people.)
 
Consequently, run something like this both inside and outside the chroot:
 
  groupadd -g 64002 sugar
  useradd -m -u 64002 -g sugar sugar
 
Then, inside the chroot, you can happily run sugar as user 'sugar' with something like
 
cat > as_person <<EOF
#!/usr/bin/env python
from os import environ, chdir, setgroups, setgid, setuid, execve
from sys import argv
from pwd import getpwnam
user = getpwnam(argv[1])
environ['HOME'] = user.pw_dir
environ['USER'] = user.pw_name
chdir(user.pw_dir)
setgroups([user.pw_gid])
setgid(user.pw_gid)
setuid(user.pw_uid)
execve(argv[2], argv[2:], environ)
EOF
chmod a+x as_person
./as_person sugar /usr/bin/sugar

Latest revision as of 20:33, 23 February 2010

Status

Purpose

You want to hack sugar. You don't want to fuss around. You want sugar-chroot.

Usage

As excerpted from the README:

sugar-chroot consists of simple scripts. Download and unpack them like so:

NV=sugar-chroot-0.1
curl http://dev.laptop.org/~mstone/releases/SOURCES/$NV.tar.xz | tar Zxf $NV.tar.xz
cd $NV

To use them, pick a supported distro:

DISTRO=debian
DISTRO=fedora

To configure:

echo $DISTRO > conf/distro
$EDITOR conf/$DISTRO.mk

Then run

sudo make r/distro

to install your chroot.

History

See http://wiki.sugarlabs.org/index.php?title=Development_Team/Chroot&oldid=36911 for the manual instructions which sugar-chroot automates.