Open Stack

On 22/09/14 11:04, Anant Patil 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?

Neither.

The only thing that matters is that we get to the state described in the 
latest template. With multiple updates rippling through at a time, it's 
likely that neither the last completed update nor the last issued update 
is representative of the current state that we need to modify.

Actually, given that updates can fail part-way through, that's already 
the case. That's why we now update the template incrementally in the 
database as we make individual changes.

cheers,
Zane.