determining image URNs for otherwise unbound RSpec at IG

[Sarah Edwards]

Hi,

This is primarily an IG/PG question, but I think others might find the answer useful.

I want to create an unbound RSpec which specifies a standard image which is locally available at each IG rack. How do I do that in a way that will be quick (ie won't require fetching an image remotely)?

For example, the following RSpec snippet requests a xen VM with a standard Fedora image (which I believe is available at all IG racks).

<node client_id="left" exclusive="false">
<sliver_type name="emulab-xen">
<disk_image name="urn:publicid:IDN+utahddc.geniracks.net+image+emulab-ops:FEDORA15-STD"/> </sliver_type>
</node>

However the image URN is rack specific (it says `utahddc.geniracks.net`). If I use this RSpec at a rack other than UtahDDC, will it:
* use an copy of that image stored at the local rack? (which is fast)
* fetch this image from UtahDDC? (which will be slow)
* give me an error? (because I used a URN from another rack)
* something else

Alternatively, I could identify the image by URL, but won't that mean that it is almost always being fetched remotely?

What is the correct way to get an otherwise unbound RSpec which specifies the image in a way that will cause a local copy to be used?

Thanks,
Sarah

*******************************************************************************
Sarah Edwards
GENI Project Office

BBN Technologies
Cambridge, MA
phone: (617) 873-2329
email: sedw...@bbn.com

[Hussamuddin Nasir]

Josh , me and Leigh had this conversation on the list a while back.
Leigh mentioned that the AM looks at the image name in the URN and
searches its local DB for that name. If present its loaded regardless of
what the rest of the URN says. If not present the request fails.


On the same note i should add that i noticed that at IG-KY we are
missing the FEDORA15-STD image for xen. So what is the standard list ?
or is IG-KY missing some images ?

cheers,

Hussam
(Hussamuddin Nasir)

Netlab Operations Team

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[Jonathon Duerig]

Nasir, one of the nice things about Xen is that there is no longer a need
for sub-os images. So if you have that image, then it should just work
within Xen.

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[Hussamuddin Nasir]

Well we do have that image in the rack DB but the protogeni_export bit was not set. I set it manually and tried to load  the image at IG-KY on a xen VM (non-exclusive) but failed. Here's the log

https://www.lan.sdn.uky.edu/spewlogfile.php3?logfile=9456d86b11bebf20f1893e79a31a5c71

cheers,

Hussam
(Hussamuddin Nasir)

Netlab Operations Team 

-------------------------------------------------------------------
Laboratory for Adv. Networking  Phone  : (859)218-0059
James F Hardymon Building       Fax    : (859)323-3740
301 Rose Street, Rm 237         E-mail : na...@netlab.uky.edu
Lexington, KY 40506-0495        Web    : http://www.netlab.uky.edu

                        University of Kentucky
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[Sarah Edwards]

Ah. I had apparently forgotten.

Thank you,
Sarah

On Dec 10, 2013, at 4:34 PM, Hussamuddin Nasir <na...@netlab.uky.edu> wrote:

> Leigh mentioned that the AM looks at the image name in the URN and searches its local DB for that name. If present its loaded regardless of what the rest of the URN says. If not present the request fails.

[Jonathon Duerig]

When Leigh was updating some of the racks yesterday, we ran into the same
error. I'm not sure what he did to fix it, though. Turn off the
protogeni_export bit for now. When we setup all the racks to have this set
of standard images, we'll apply whatever Leigh's fix was.

> ����<disk_imagename="urn:publicid:IDN+utahddc.geniracks.net+image+emulab-ops:FEDORA15-STD"

[Nicholas Bastin]

On Tue, Dec 10, 2013 at 4:30 PM, Sarah Edwards <sedw...@bbn.com> wrote:

I want to create an unbound RSpec which specifies a standard image which is locally available at each IG rack. How do I do that in a way that will be quick (ie won't require fetching an image remotely)?

Templates?  :-)  (I have a python library that does this, I should probably make this more generally available) 

 

For example, the following RSpec snippet requests a xen VM with a standard Fedora image (which I believe is available at all IG racks).

<node client_id="left" exclusive="false">
        <sliver_type name="emulab-xen">
        <disk_image name="urn:publicid:IDN+utahddc.geniracks.net+image+emulab-ops:FEDORA15-STD"/>       </sliver_type>
</node>

I believe I know the answers to some of these questions...someone correct me if I'm wrong but I've been building images and using them a lot lately. 

 

However the image URN is rack specific (it says `utahddc.geniracks.net`).  If I use this RSpec at a rack other than UtahDDC, will it:
 * use an copy of that image stored at the local rack? (which is fast)

If it's already been used once at rack X, then it will be available locally at rack X.  For better or worse image names ignore their URNs, so standard images are generally instantly available at every rack.

 

 * fetch this image from UtahDDC? (which will be slow)

It will do this if the image is not available locally.

 

 * give me an error? (because I used a URN from another rack)

This is certainly legal for custom images, so I doubt it's any different for the standard ones.

 

Alternatively, I could identify the image by URL, but won't that mean that it is almost always being fetched remotely?

Still only the first time for each rack (there may be some aging, but certainly in the short term the image is cached).

--

Nick 

[Leigh Stoller]

> However the image URN is rack specific (it says
> `utahddc.geniracks.net`). If I use this RSpec at a rack other than
> UtahDDC, will it:
> * use an copy of that image stored at the local rack? (which is fast)

Hi Sarah. As a convenience to users, we ignore the authority part of the
disk image so that you do not have to worry about. FEDORA15-STD always
refers to the local copy, no matter what the authority in the URN says.

Lbs