Open Stack

Excerpts from Angus Salkeld's message of 2014-09-22 20:31:46 -0700:
> On Tue, Sep 23, 2014 at 1:04 AM, Anant Patil <anant.patil at hp.com> wrote:
> 
> > Hi,
> >
> > In convergence, we discuss about having concurrent updates to a stack. I
> > wanted to know if it is safe to assume that the an update will be a
> > super set of it's previous updates. Understanding this is critical to
> > arrive at implementation of concurrent stack operations.
> >
> > Assuming that an admin will have VCS setup and will issue requests by
> > checking-out the template and modifying it, I could see that the updates
> > will be incremental and not discreet. Is this assumption correct? When
> > an update is issued before a previous update is complete, would the
> > template for that be based on the template of previously issued
> > incomplete update or the last completed one?
> >
> 
> I don't think you can assume anything about the update. What if the user
> just posts a
> totally different template? That is still a valid update. Or they post an
> empty template
> to delete the resources.

Agreed. The new template simply replaces the graph with a new version.
If that graph happens to change everything, then the old things will now
be in a "should not exist" desired state and the new template convergence
should remove them when it gets to the garbage collection at the end.