PhoenixBlog20081030x1645 < LCGTier2

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KeyWords: SysAdmin, [[Xen]]


---+ xen-strap

Kudos to [[mailto:m.klein@rl.ac.uk Marian Klein]] for writing the _truly amazing_ 
script ==xen-strap==!  It can bootstrap a Xen !DomU based on
any of: Scientific Linux 4.x/5.x (also in the CERN variants), CentOS
4.x/5.x, or Debian etch/lenny/sid.  And all of this in _one single script_
with no dependencies - just [[http://www.gridpp.rl.ac.uk/pps/xen-strap/xen-strap download]] 
and run.  It hasn't been from the C64 times that I have seen a tool
requiring no configuration at all!

Last but not least, it install a truly _minimal_ system: no need to
have X11 or other fat daemons running on VMs...

Here is the incantation I used to build a template SL4.7 !DomU:
<verbatim>
  /root/xen-strap --name=sl4-template \
    --memory=1024 \
    --size=8G \
    --label=root \
    --noswap \
    --mac=00:16:3E:00:66:01 \
    --dhcp \
    --ssh \
    --update \
    --locales-en-only \
    --dwc --no-ntp \
    --post-install="host:/var/cfengine/scripts/newmachine" \
    sl47 \
    lvm:vg_root/sl4template:8G \
    ftp://mirror.switch.ch/mirror/scientificlinux/47/i386/SL/RPMS/
</verbatim>
A few words of explanation:
   * =--name= is the name of the Xen configuration generated in =/etc/xen=, and also the hostname (unless overridden with =--hostname=)
   * =--size= is the size of the partition/LV that ==xen-strap== will create for hosting the VM's root filesystem;
   * =--label= is the label of the VM root filesystem (as seen from _inside_ the VM);
   * =--noswap= turns off creating a swap partition for the VM;
   * =--mac=...= sets the MAC address (not in the mainstream ==xen-strap==, you need to apply the patch below)
   * =--dhcp= will configure the !DomU to use DHCP for networking;
   * =--ssh= will install and enable the SSH server on the !DomU;
   * =--update= will start an OS update after everything has been installed;
   * =--locales-en-only= will remove non-English locales, saving some space on the !DomU disk;
   * =--dwc --no-ntp= turns off the NTP daemon in the !DomU (will use the clock in the Dom0, no worry);
   * =--post-install="host:/path/to/script"= runs the post-install script found on the Dom0 at /path/to/script;
   * =sl46= is the distribution to install (Scientific Linux 4.7, you need to apply the patch below - stock ==xen-strap== only has 4.6)
   * =lvm:...= creates the specified LV to host the !DomU root filesystem;
   * the rest is the OS mirror URL - if you don't specify it, you get ==xen-strap=='s default choice (which is in the UK).

The long story and explanations can be found in the 
[[http://www.gridpp.ac.uk/wiki/ GridPP Wiki]]: 
  http://www.gridpp.ac.uk/wiki/Xen-strap

---++ Readers' comments

%COMMENT{type="below"}%

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
diff	xen-strap.diff	r1	manage	13.0 K	2008-10-30 - 17:11	RiccardoMurri	Patch to enable: 1) SL4.7 install; 2) the --mac-address=... command-line option; 3) creation of the empty workdir with "mktemp"