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From Chris Lalancette <clala...@redhat.com>
Subject Re: Question about instance states
Date Thu, 07 Oct 2010 17:04:48 GMT
On 10/07/10 - 05:27:28AM, Ladislav Martincik wrote:
> Hey guys,
> 
> I have already asked the question on ICQ channel, but I think it deserves it's own thread
on this mailing list.
> 
> At the moment I'm working on Linode driver for Deltacloud Core project and I'm having
problem map all Linode instance states to our Deltacloud default states. Currently we have
PENDING, RUNNING, SHUTTING_DOWN, STOPPED. Linode has 3 other states from which 2 can be mapped
to our standard PENDING state but 1 called "Boot failed" cannot be.
> 
> There seems to be 2 obvious ways to go:
> 
> 1) Create one more state which we can call UNKNOWN and pull all the other states into
this status.
> pros: It's simple solution and easy to handle.
> cons: Some of the states could be important to outside world and we will just dump them
into one unknown state
> 
> 2) Let each driver populate different as strings to our API
> pros: Transparent for outside world.
> cons: Can be problematic for different clients as they could rely on predefined states
for their apps.

There is another downside to 2), in that if each individual driver specifies
it's own set of states, then you cannot write a generic client; your client
needs to know whether it is using EC2, or Linode, or Rackspace, etc.  That
defeats the whole purpose of deltacloud.  In my opinion, option 1 is the only
reasonable choice; define it as a state that all drivers could use, and then
just define it for the ones that can actually get there.

FYI: recently we removed the "SHUTTING_DOWN" state, since it was poorly
defined.  Therefore, the only valid states at present are PENDING, RUNNING,
and STOPPED.

-- 
Chris Lalancette

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