[Hawkular-dev] Inventory and 'transient' servers

[Heiko W.Rupp]

On 24 Jan 2017, at 10:35, Joel Takvorian wrote:

> Re-using the state would mean there's always 1 or 0 running instance of
> that server at a given time, but what happens if it's scaled up to 2
> instances or more? Is it a possible scenario? If yes, it seems

Yes of course it is possible. And the number of running
servers for a given DC can be scaled up and down "at will".

> complicated
> to use dc+version+tenant as the feed id.

Yes I am aware that this is not enough - was more meant
to be an example.

> I filed an issue in JIRA about introducing some kind of TTL :
> https://issues.jboss.org/browse/HWKINVENT-205
> Maybe those expired feeds fall in the scope of this issue.

Yes, a TTL could be a good solution. If a server re-connects
we reset the "last seen" value. We need to make sure to set the
TTL long enough that a short outage does not expire
servers that are not in containers.

Perhaps we need to also store some information in inventory
if the server is in containers or not (well, we need that
info anyway, see e.g.
https://issues.jboss.org/browse/HAWKULAR-1186 )
For the inventory use case we should perhaps expose
this more prominently than just 'hidden away' in some
property in some json.