Difference between revisions of "Development Team/Chroot"

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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.
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=== Status ===
  
=== Chroot Construction ===
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* 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.
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=== Purpose ===
  
==== debootstrap ====
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''You want to hack sugar. You don't want to fuss around. '''You want sugar-chroot.'''''
With debootstrap, in order to get a working chroot, you want something like:
 
  
  export CHROOT=`pwd`/sid-root
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=== Usage ===
  sudo 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
 
  
''Reference: http://www.debian.org/doc/manuals/reference/ch-tips.en.html ''
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As excerpted from the '''[http://dev.laptop.org/git/users/mstone/sugar-chroot/plain/README README]''':
  
==== mock ====
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sugar-chroot consists of simple scripts. Download and unpack them like so:
With mock, it would be more like:
 
  
  mock -r fedora-devel-i386 --init
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NV=sugar-chroot-0.1
  mock -r fedora-devel-i386 --shell
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curl http://dev.laptop.org/~mstone/releases/SOURCES/$NV.tar.xz | tar Zxf $NV.tar.xz
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cd $NV
  
=== X11 ===
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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:
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DISTRO=debian
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DISTRO=fedora
  
# bind-mount the X unix socket into the chroot.
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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:
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echo $DISTRO > conf/distro
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$EDITOR conf/$DISTRO.mk
  
Xephyr -ac :1
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Then run
  
And, ''inside'' the chroot, set the <tt>DISPLAY</tt> to <tt>localhost:1</tt>.
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sudo make r/distro
  
=== D-Bus ===
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to install your chroot.
  
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
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=== History ===
  
  mount --bind /var/run/dbus $CHROOT/var/run/dbus
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See http://wiki.sugarlabs.org/index.php?title=Development_Team/Chroot&oldid=36911 for the manual instructions which sugar-chroot automates.
 
 
before entering the chroot. (Mock uses unshare() to enter a new mount-point namespace since this makes garbage collection of mountpoints much easier.)
 
 
 
It also wants to have a session bus so, ''inside'' the chroot:
 
 
 
  export DBUS_SESSION_BUS_ADDRESS=$(dbus-daemon --session --print-address --fork)
 
 
 
=== 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
 
 
 
 
 
== Jhbuild ==
 
 
 
After, you can also build sugar inside your chroot without compromising your ''main'' system.
 
 
 
*[[Development Team/Jhbuild]]
 

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.