Each domain should get their own directory structure. Since you are
using chroot you will require duplicate copies of the shared
libraries, binaries, conf files, etc. I use /virtual/domain1.com for
each domain that I create.
I realize that you are taking up more disk space but it is cheaper than a whole new machine and network cards. If you really want to preserve space you can hard link the files together so only one copy of each binary exists. The filesystem that I use takes up a little over 2M. However, this script attempts to copy all the files from the main filesystem in order to be as generic as possible.
Here is a sample virtfs script:
#!/bin/sh
echo '$Revision: 1.49 $'
echo -n "Enter the domain name: "
read domain
if [ "$domain" = "" ]
then
echo Nothing entered: aborting
exit 0
fi
leadingdir=/virtual
echo -n "Enter leading dir: (Enter for default: $leadingdir): "
read ans
if [ "$ans" != "" ]
then
leadingdir=$ans
fi
newdir=$leadingdir/$domain
if [ -d "$newdir" ]
then
echo New directory: $newdir: ALREADY exists
exit 0
else
echo New directory: $newdir
fi
echo Create $newdir
mkdir -p $newdir
echo Create bin
cp -pdR /bin $newdir
echo Create dev
cp -pdR /dev $newdir
echo Create dev/log
ln -f /virtual/log $newdir/dev/log
echo Create etc
mkdir -p $newdir/etc
for i in /etc/*
do
if [ -d "$i" ]
then
continue
fi
cp -pd $i $newdir/etc
done
echo Create etc/skel
mkdir -p $newdir/etc/skel
echo Create home
for i in a b c d e f g h i j k l m n o p q r s t u v w x y z
do
mkdir -p $newdir/home/$i
done
echo Create home/c/crc
mkdir -p $newdir/home/c/crc
chown crc.users $newdir/home/c/crc
echo Create lib
mkdir -p $newdir/lib
for i in /lib/*
do
if [ -d "$i" ]
then
continue
fi
cp -pd $i $newdir/lib
done
echo Create proc
mkdir -p $newdir/proc
echo Create sbin
cp -pdR /sbin $newdir
echo Create tmp
mkdir -p -m 0777 $newdir/tmp
chmod +t $newdir/tmp
echo Create usr
mkdir -p $newdir/usr
echo Create usr/bin
cp -pdR /usr/bin $newdir/usr
echo Create usr/lib
mkdir -p $newdir/usr/lib
echo Create usr/lib/locale
cp -pdR /usr/lib/locale $newdir/usr/lib
echo Create usr/lib/terminfo
cp -pdR /usr/lib/terminfo $newdir/usr/lib
echo Create usr/lib/zoneinfo
cp -pdR /usr/lib/zoneinfo $newdir/usr/lib
echo Create usr/lib/\*.so\*
cp -pdR /usr/lib/*.so* $newdir/usr/lib
echo Create usr/sbin
cp -pdR /usr/sbin $newdir/usr
echo Linking usr/tmp
ln -s /tmp $newdir/usr/tmp
echo Create var
mkdir -p $newdir/var
echo Create var/lock
cp -pdR /var/lock $newdir/var
echo Create var/log
mkdir -p $newdir/var/log
echo Create var/log/wtmp
cp /dev/null $newdir/var/log/wtmp
echo Create var/run
cp -pdR /var/run $newdir/var
echo Create var/run/utmp
cp /dev/null $newdir/var/run/utmp
echo Create var/spool
cp -pdR /var/spool $newdir/var
echo Linking var/tmp
ln -s /tmp $newdir/var/tmp
echo Create var/www/html
mkdir -p $newdir/var/www/html
chown webmast.www $newdir/var/www/html
chmod g+s $newdir/var/www/html
echo Create var/www/master
mkdir -p $newdir/var/www/master
chown webmast.www $newdir/var/www/master
echo Create var/www/server
mkdir -p $newdir/var/www/server
chown webmast.www $newdir/var/www/server
exit 0
To execute commands in a virtual environment you have to
chroot to that directory and then run the command.
I have written a special shell script called virtexec
that handles this for any command:
#!/bin/sh
echo '$Revision: 1.49 $'
BNAME=`basename $0`
FIRST4CHAR=`echo $BNAME | cut -c1-4`
REALBNAME=`echo $BNAME | cut -c5-`
if [ "$BNAME" = "virtexec" ]
then
echo Cannot run virtexec directly: NEED a symlink
exit 0
fi
if [ "$FIRST4CHAR" != "virt" ]
then
echo Symlink not a virt function
exit 0
fi
list=""
num=1
for i in /virtual/*
do
if [ ! -d "$i" ]
then
continue
fi
if [ "$i" = "/virtual/lost+found" ]
then
continue
fi
list="$list $i $num"
num=`expr $num + 1`
done
if [ "$list" = "" ]
then
echo No virtual environments exist
exit 0
fi
dialog --clear --title 'Virtexec' --menu Pick 20 70 12 $list 2> /tmp/menu.$$
if [ "$?" = "0" ]
then
newdir=`cat /tmp/menu.$$`
else
newdir=""
fi
tput clear
rm -f /tmp/menu.$$
echo '$Revision: 1.49 $'
if [ ! -d "$newdir" ]
then
echo New directory: $newdir: NOT EXIST
exit 0
else
echo New directory: $newdir
fi
echo bname: $BNAME
echo realbname: $REALBNAME
if [ "$*" = "" ]
then
echo args: none
else
echo args: $*
fi
echo Changing to $newdir
cd $newdir
echo Running program $REALBNAME
chroot $newdir $REALBNAME $*
exit 0
Please note that you must have the dialog program installed on
your system for this to work. To use virtexec just symlink a
program to it. For example,
ln -s /usr/local/bin/virtexec /usr/local/bin/virtpasswd ln -s /usr/local/bin/virtexec /usr/local/bin/virtvi ln -s /usr/local/bin/virtexec /usr/local/bin/virtpico ln -s /usr/local/bin/virtexec /usr/local/bin/virtemacs ln -s /usr/local/bin/virtexec /usr/local/bin/virtmailq
Then if you type virtvi or virtpasswd or virtmailq it will allow you to vi a program, change a user's password or check the mail queue on your virtual system. You can create as many virtexec symlinks as you want. Please note that if your program requires a shared library it has to be in the virtual filesystem as well as the binary.
I install all the scripts in /usr/local/bin. Anything that I do not want to put on the virtual filesystem I put in /usr/local. The script does not copy any of the files in /usr/local to the virtual filesystem. Any files that are important to not cross virtual filesystems should be removed. For example, ssh is installed on my system and I did not want the private key for the server available on all the virtual filesystems so I remove it from each virtual filesystem after I run virtfs. I also change resolv.conf and remove anything that has the name of another domain on it for legal reasons. For example, /etc/hosts and /etc/HOSTNAME.
The programs that I symlink to virtexec are: