[Openstack-devel] New Debconf template for the nova source package

[Thomas Goirand]

On 06/20/2012 01:01 AM, Justin B Rye wrote:
> Thomas Goirand wrote:
>> Template: nova-compute-xen/xenapi_url
>> Type: string
>> Default: https://my-dom0.example.com
>> _Description: Address of the XenAPI dom0:
>>  Nova Compute Xen needs to know the address of the server running XenAPI. This
>>  can be a server running XenServer, the Citrix CentOS XCP appliance installed
>    ^^^
> s/can/may/, probaby.  I'm not 100% clear whether I should be reading
> this as a list of three possible kinds of *server* or three kinds of
> *software* that the server is running...

Let me explain then. First, there was XenServer, a closed source product
from Citrix (license fee was around 500 USD / year / server). Then they
decided to open source it, and released Xen Cloud Platform (XCP). It was
(and still is) possible to download this CentOS iso image. Then they
realized that having the product open source, being invasive and
changing many things in the system didn't make much sense and was hard
to maintain. So they released XCP, and I worked with them to package it
in Debian. The main package name is called xcp-xapi (source package
xen-api), which is what you have to install in Debian, and what has been
called "project Kronos". All of these are providing "xen api" (or xapi).

Obviously, my intention here was to make the promotion of the Debian
package, even though all of the flavors of Xen-API will work.

>>  from Citrix ISO image, or even a Debian server running Xen Cloud Platform
>        ^
> Possibly "from a Citrix ISO image"; or conceivably even "from the
> Citrix ISO image", depending on how many such images I have got to
> choose from.
> 
> When you say "Debian server", do you mean some sort of xen.debian.net
> or just any machine running a Debian-based distro?

I mean a Debian-based server, with xcp-xapi installed and running.

>>  (XCP / Kronos project), which is available directly in Debian under the
> 
> The reference to "(XCP / Kronos Project)" is confusing.  Try "running
> the Kronos Project's Xen Cloud Platform (available as the package
> xcp-xapi)".
> 
>>  package name xcp-xapi. You can enter an IP address or a fully qualified domain
>>  name if it resolves correctly.
> 
> Is that condition applicable to both options or is it just a warning
> against using hostnames without reliable DNS?

Just a warning that Openstack should be able to find the IP out of the
hostname, either using /etc/hostnames or DNS.

> I'd suggest:
>    Nova Compute Xen needs to know the address of the server running XenAPI. This
>    may be a server running XenServer, the Citrix CentOS XCP appliance installed
>    from a Citrix ISO image, or even the Kronos Project's Xen Cloud Platform
>    (available as the package xcp-xapi). You can enter an IP address, or a fully
>    qualified domain name if it resolves correctly.

The last sentence is perfect, though the first one is a bit confusing to
me now. To make it clear, there's:
- Citrix XenServer (iso image appliance, CentOS based)
- Citrix Xen Cloud Platform or XCP appliance (iso image appliance,
CentOS based)
- XenAPI available as the xcp-xapi Debian package (available in both
Debian and Ubuntu)

All of the above are ok, and would run with openstack-compute-xen.

I do find hard to write this as a short and correct English sentence,
but I think we could write:

> Nova Compute Xen needs to know the address of the server running
> XenAPI. This may be a server running Citrix XenServer, the Citrix
> CentOS XCP appliance installed from an ISO image, or even the
> Kronos Project's Xen Cloud Platform (available in Debian and Ubuntu
> as the package xcp-xapi). You can enter an IP address, or a fully
> qualified domain name if it resolves correctly.

> [...]
>> Template: nova-compute-xen/xenapi_password
> 
> No please_type_it_again and oops_they_dont_match messages?

Do you find it nice? I find it rather annoying, and not necessary in
this case, because If the password is wrong, it can anyway be changed
later on in /etc/nova/nova-compute.conf. Also, I like Debconf, but it is
there mainly so that we can use preseeding later on (it's the best way
to do automatic installs). Maybe we should tell about this fact in the
Debconf template?

>> [...] Also, I'm not sure if we need that much
>> information on the first message (eg: maybe only having "Please enter
>> the address of your XenAPI server." may be enough).
> 
> It's hard to guess without being more familiar with XenAPI use cases.
> One option might be to spit out the crucial instructions from the
> supplementary hints:
> 
>    Nova Compute Xen needs to know the address of the server running XenAPI,
>    either as an IP address or a resolvable fully qualified domain name.
>    .
>    The server may be running XenServer, the Citrix CentOS XCP appliance
>    installed from a Citrix ISO image, or even the Kronos Project's Xen
>    Cloud Platform (available as the package xcp-xapi).
> 
> (Or indeed drop the second paragraph.)

Yes, doing like above is really cool. Thanks for the suggestion.

So, where down to:

> Nova Compute Xen needs to know the address of the server running
> XenAPI. You can enter an IP address, or a fully qualified domain name
> if it resolves correctly.
> .
> This may be a server running Citrix XenServer, the CentOS Xen Cloud
> Patform (XCP) appliance installed from an ISO image, or even the
> Kronos Project's XCP (available in Debian and Ubuntu as the package
> xcp-xapi).

(please note that I rewrote a bit the last sentence)

Does it look good now?

Thomas