I had some additional questions/comments on the Image Synchronization Options ( 
https://wiki.openstack.org/wiki/Image_handling_in_edge_environment ):


One Glance with multiple backends

·         In this scenario, are all Edge Clouds simply configured with the one 
central glance for its GLANCE ENDPOINT ?

o    i.e. GLANCE is a typical shared service in a multi-region environment ?

·         If so,
how does this OPTION support the requirement for Edge Cloud Operation when 
disconnected from Central Location ?



Several Glances with an independent synchronization service    (PUSH)

·         I refer to this as the PUSH model

·         I don’t believe you have to ( or necessarily should) rely on the 
backend to do the synchronization of the images

o    i.e. the ‘Synch Service’ could do this strictly through Glance REST APIs
(making it independent of the particular Glance backend ... and allowing the 
Glance Backends at Central and Edge sites to actually be different)


·         I think the ‘Synch Service’ MUST be able to support 
‘selective/multicast’ distribution of Images from Central to Edge for Image 
Synchronization

o    i.e. you don’t want Central Site pushing ALL images to ALL Edge Sites ... 
especially for the small Edge Sites


·         Not sure ... but I didn’t think this was the model being used in 
mixmatch ... thought mixmatch was more the PULL model (below)



One Glance and multiple Glance API Servers   (PULL)

·         I refer to this as the PULL model

·         This is the current model supported in StarlingX’s Distributed Cloud 
sub-project

o    We run glance-api on all Edge Clouds ... that talk to glance-registry on 
the Central Cloud, and

o    We have glance-api setup for caching such that only the first access to an 
particular image incurs the latency of the image transfer from Central to Edge

·

·         this PULL model affectively implements the location aware 
synchronization you talk about below,  (i.e. synchronise images only to those 
cloud instances where they are needed)?


In StarlingX Distributed Cloud,
We plan on supporting both the PUSH and PULL model ... suspect there are use 
cases for both.

Greg.





From: "Csatari, Gergely (Nokia - HU/Budapest)" <gergely.csat...@nokia.com>
Date: Thursday, June 7, 2018 at 6:49 AM
To: "openstack-dev@lists.openstack.org" <openstack-dev@lists.openstack.org>, 
"edge-comput...@lists.openstack.org" <edge-comput...@lists.openstack.org>
Subject: Re: [Edge-computing] [edge][glance][mixmatch]: Wiki of the possible 
architectures for image synchronisation

Hi,

I did some work ont he figures and realised, that I have some questions related 
to the alternative options:

Multiple backends option:
-          What is the API between Glance and the Glance backends?
-          How is it possible to implement location aware synchronisation 
(synchronise images only to those cloud instances where they are needed)?
-          Is it possible to have different OpenStack versions in the different 
cloud instances?
-          Can a cloud instance use the locally synchronised images in case of 
a network connection break?
-          Is it possible to implement this without storing database 
credentials ont he edge cloud instances?

Independent synchronisation service:
-          If I understood [1<https://mixmatch.readthedocs.io/en/latest/>] 
correctly mixmatch can help Nova to attach a remote volume, but it will not 
help in synchronizing the images. is this true?


As I promised in the Edge Compute Group call I plan to organize an IRC review 
meeting to check the wiki. Please indicate your availability in 
[2<https://doodle.com/poll/bddg65vyh4qwxpk5>].

[1]: https://mixmatch.readthedocs.io/en/latest/
[2]: https://doodle.com/poll/bddg65vyh4qwxpk5

Br,
Gerg0

From: Csatari, Gergely (Nokia - HU/Budapest)
Sent: Wednesday, May 23, 2018 8:59 PM
To: OpenStack Development Mailing List (not for usage questions) 
<openstack-dev@lists.openstack.org>; edge-comput...@lists.openstack.org
Subject: [edge][glance]: Wiki of the possible architectures for image 
synchronisation

Hi,

Here I send the wiki page 
[1<https://wiki.openstack.org/wiki/Image_handling_in_edge_environment>] where I 
summarize what I understood from the Forum session about image synchronisation 
in edge environment [2], [3].

Please check and correct/comment.

Thanks,
Gerg0


[1]: https://wiki.openstack.org/wiki/Image_handling_in_edge_environment
[2]: https://etherpad.openstack.org/p/yvr-edge-cloud-images
[3]: 
https://www.openstack.org/summit/vancouver-2018/summit-schedule/events/21768/image-handling-in-an-edge-cloud-infrastructure
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