Default affinity

[jhamman]

At this point, this is for illustration purposes only. It builds on #145 and gives #146 a try. By default, this now creates dask-worker pods with the following affinity and tolerations:

spec:
  affinity:
    nodeAffinity:
      preferredDuringSchedulingIgnoredDuringExecution:
      - preference:
          matchExpressions:
          - key: k8s.dask.org/node-purpose
            operator: In
            values:
            - worker
        weight: 100
  tolerations:
  - effect: NoSchedule
    key: k8s.dask.org/dedicated
    operator: Equal
    value: worker
  - effect: NoSchedule
    key: k8s.dask.org_dedicated
    operator: Equal
    value: worker
  - effect: NoExecute
    key: node.kubernetes.io/not-ready
    operator: Exists
    tolerationSeconds: 300
  - effect: NoExecute
    key: node.kubernetes.io/unreachable
    operator: Exists
    tolerationSeconds: 300

If my understanding is correct: A kubernetes cluster / node-pool with the following labels/taints should attract and accept dask-workers with this spec.

labels:

• k8s.dask.org/node-purpose : worker

taints:

• k8s.dask.org/dedicated=worker
• k8s.dask.org_dedicated=worker

I should note that I have a node-pool with these options set and my dask-workers are not landing in the desired place yet so I'm probably still missing at least one piece of the puzzle.

[mrocklin]

@quasiben if you have a moment can I ask you to check out this PR?

[jacobtomlinson]

Again this looks reasonable to me.

[jhamman]

Thanks @jacobtomlinson - I need to add a unit test or two but now that its passed your sniff test, I can forge ahead.

[jhamman]

I'm working on tests now. I've also created a binder with this branch on it that can be run on binder.pangeo.io:

[consideRatio]

I've done partial state handling in #148, doing this was really messy sadly.

[consideRatio]

You are very welcome to copy/paste/modify etc. to accomplish the desired outcome.

[jhamman]

@consideRatio - I merged our two efforts. Let me know what you think.

[consideRatio]

@jhamman LGTM except a small technical typo (I think).

[consideRatio]

The assignment above should be an array I think. If we could say the type of elements it should be an array of V1PreferredSChedulingTerm objects, but as we cannot type the arrays element it should simply be an array.

I understand it currently as it is a tuple with one element: an array. I'm not confident on how the parenthesis are interpreted though.

[jhamman]

This evaluates to an empty list.

In [1]: x = ([])

In [2]: x
Out[2]: []

As you say, we can't type this further. AFAIK, there isn't a way to instantiate an empty list of V1PreferredSchedulingTerm objects, like we do for the V1NodeSelectors above.

[consideRatio]

Ah okay! Technically then all good!!

I just learned that () is a 0-tuple or a tuple with 0 elements, and ("test",) is a tuple with 1 element, and ("test", "more") is a tuple with two elements, but ("something") is just "something".

[consideRatio]

LGTM!

[jhamman]

@yuvipanda / @jacobtomlinson - I think we're all done here. Ready to merge?