vserver

vserver is a kernel patch plus userland utils that lets you run multiple independent Linux servers inside a single physical server. To find out what vserver is about, see Jacques Gélinas' paper on vserver and then look at the new vserver project web site.

I've been using vserver since Jan 2002. In that time I've written a few Perl scripts to automate the generation of new virtual servers, but they haven't been fit for public release. Recently I discovered the Joy of Yum, and so I wrote a small shell script that uses yum to create a Fedora Core 1 vserver:

• vserver-fc1

The script has everything hard-coded, but is so small that it's not hard to read and understand it all.

Two non-obvious things to note:

• When I used the glibc from FC1 inside a vserver, it didn't want to let some important programs (such as RPM) run. I presume this is due to some bad interaction with the kernel I am running on the base server (you might not have this problem). To fix it, I rebuilt the glibc RPM after applying the following patch to the spec file (patch 3 is glibc-execstack-disable.patch):

  --- glibc.spec.orig     2003-11-12 09:17:31.000000000 +1030
  +++ glibc.spec  2003-11-17 23:40:48.000000000 +1030
  @@ -1,4 +1,4 @@
  -%define glibcrelease 101.1
  +%define glibcrelease 101.1nc1
   %define auxarches i586 i686 athlon sparcv9 alphaev6
   %define prelinkarches noarch
   %define nptlarches i686 athlon x86_64 ia64 s390 s390x sparcv9 ppc ppc64
  @@ -265,9 +265,9 @@
   gcc*\ 3.2.3*)
     case "`uname -r`" in *.ent*|*.EL*)
   %patch2 -p1
  -%patch3 -p1
     ;; esac ;;
   esac
  +%patch3 -p1
   %patch4 -p1
   %patch5 -p1
   %patch6 -p1
  

• The /tmp/utmp file referenced in the script is a utmp with just a runlevel record in it, which I use to silence the "cannot determine current run level" warnings from chkconfig. If you can't figure out how to create one of those you can comment out the line that refers to it, but can someone come up with an easy way to create that file?