Distinct Host constraint accepts bool or string.

[dadgar]

Distinct Host constraint accepts bool or string.

Fixes #489

[diptanu]

Extract this in a method like toBool? I think it would read better.

[c4milo]

@dadgar, I'm curious, why wasn't this constrain handled through the generic constraint configuration? I'm also wondering if having a distinct_datacenter option will make sense within the context of the scheduling algorithms. Or, do you think that by having the scheduling dynamism the need for that type of constrain would be irrelevant.

[dadgar]

The distinct data center is an interesting constraint. It is definitely
something Nomad is capable of. As for why distinct host is treated
differently, the normal constraints actually just restrict feasible nodes
based on their attributes. Distinct nodes restricts based on existing and
planned allocations. There will be more of these types of constraints so it
was easier to separate them.
On Fri, Nov 27, 2015 at 6:14 AM Camilo Aguilar [email protected]
wrote:

@dadgar https://github.com/dadgar, I'm curious, why wasn't this
constrain handled through the generic constraint configuration? I'm also
wondering if having a distinct_datacenter option will make sense within the
context of the scheduling algorithms. Or, do you think that by having the
scheduling dynamism the need for that type of constrain would be irrelevant.

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Reply to this email directly or view it on GitHub
#501 (comment).

[diptanu]

@c4milo @dadgar I think instead of distinct_datacenter, something on the lines of "Balance across DataCenters" is more effective. People usually want the scheduler to run services equally across all the fault domains, for ex: spread the third of workload of a service across every AWS Zones.

One can achieve distinct DCs by having the count same as number of DCs and number of DCs don't change everyday :)

[c4milo]

@diptanu, right, balancing is what I'm looking for as well. I'm going to create a new issue to keep track of that.

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