Units & resources: are units homogeneous?

[Adam Collard]

Hi Katherine,


On Tue, 16 Feb 2016 at 18:20 Katherine Cox-Buday <
katherine.cox-buday at canonical.com> wrote:

> The team is looking closely at some of our CLI surrounding resources, and
> an interesting question came up: should units be considered homogeneous?
>
> My understanding is that it's a goal to make the management of units more
> consistent, and making the units more homogeneous would support this, but
> I'm wondering from a workload perspective if this is also true? One example
> I could think of to support the discussion is a unit being elected leader
> and thus taking a different path through it's workflow than the other
> units. When it comes to resources, maybe this means it pulls a different
> sub-set of the declared resources, or maybe doesn't pull resources at all
> (e.g. it's coordinating the rest of the units or something).
>

Yes, as a concrete example the Landscape charm[0], does just that and runs
different Landscape services on different units, using the leader to decide
what goes where. The units are heterogeneous and under the control of the
charm.

Cheers,

Adam

[0] https://jujucharms.com/landscape-server/trusty/
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