Building Xenopsd

Xenopsd is the "domain management" component within the XCP toolstack.

Prerequisites

You will need:

1. the normal build tools (on Debian install "build-essential git rsync wget")
2. the Xen development headers (on Debian install "libxen-dev")
3. the OCaml compiler (at least version 3.12.1)
4. the OCaml package manager, OPAM

Assuming a Debian wheezy system (other systems may differ), first install the system packages:

 $ sudo apt-get install build-essential git rsync wget libxen-dev ocaml

Then install the OPAM tool:

 $ wget http://github.com/OCamlPro/opam/archive/0.8.3.tar.gz
 $ tar -xvzf 0.8.3.tar.gz
 $ cd opam-0.8.3
 $ ./configure
 $ make
 $ sudo make install

NB the current release fails to build because it tries to download a dependency from a broken URL: https://github.com/OCamlPro/opam/issues/356

Next initialise OPAM, this will read in the definitions of common OCaml packages.

 $ opam init

Since OPAM packages are installed by default into a custom directory in $HOME/.opam, it's necessary to update some paths. The instructions will be printed to your terminal and typically look like the following:

To update $PATH, $MANPATH, $OCAML_TOPLEVEL_PATH, $CAML_LD_LIBRARY_PATH; you can now run:
           
   $ which opam && eval `opam config -env`

and add this in your ~/.profile

Building xenopsd (and associated tools)

To make building easy, the development versions of xenopsd (and associated tools) are packaged into OPAM packages in a custom repository. To build, first add this repository as a remote:

 $ opam remote -add xen-dev git://github.com/xen-org/opam-repo-dev

The new packages found in this remote will be listed on your terminal and may be queried via "opam list". At the time of writing this list looked like:

The following NEW packages are available:
- fd-send-recv.1.0.0
- forkexecd.1.0.0
- message_switch.1.0.0
- shared-memory-ring.1.0.0
- xcp.1.0.0
- xen-api-client.1.0.0
- xenctrl.4.1.0
- xenops-cli.1.0.0
- xenopsd.1.0.0
- xenstore.2.0.0
- xenstore_transport.1.0.0

Finally, to build xenopsd (and its CLI) and all their dependencies, use the following command:

 $ opam install xenopsd xenops-cli

The xenospd binary will end up in .opam/system/bin and should be on your $PATH (if you followed the earlier instructions to update your environment)

Running xenopsd

The build process also creates a basic configuration file. It can be started using:

 $ sudo ./.opam/system/bin/xenopsd -config ./.opam/system/etc/xenopsd.conf

by default it will not daemonize and continue writing debug messages to the terminal.

To read the CLI help, try:

 $ xenops-cli
 $ xenops-cli add --help

Starting a simple VM

The xenops-cli is able to read and write VM config files in xm/xl syntax. First create a file with contents like:

TBD

Future

There's lots of stuff to do, including:

1. add support for libxl (in progress: Rob Hoes is working on it)
2. update the Debian packages (Mike McClurg is working on it)
3. package up squeezed, rrdd and xapi in the same way
4. separate the storage code from xapi so it can be used without xapi

Development

If you're interested in taking part or influencing development:

1. join the mailing list <xen-api@lists.xen.org>
2. join the IRC channel #xen-api on freenode
3. check out the code on http://github.com/djs55/xenopsd