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feat: add anti affinity to coredns deployment #249

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Jan 9, 2019
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feat: add anti affinity to coredns deployment #249

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21 changes: 21 additions & 0 deletions parts/k8s/addons/coredns.yaml
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Expand Up @@ -100,6 +100,27 @@ spec:
annotations:
seccomp.security.alpha.kubernetes.io/pod: docker/default
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
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Let's try to summarize what this is expressing. Is it:

"Don't schedule coredns pods onto a node that already has a kube-dns-labeled pod in the same availability zone."

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Yes, except it will only try, if it can't it will schedule both pods on the same node if no other is available.

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Indeed, thanks. Hence the preferredDuringSchedulingIgnoredDuringExecution instead of requiredDuringSchedulingIgnoredDuringExecution.

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Exactly

labelSelector:
matchExpressions:
- key: k8s-app
operator: In
values:
- kube-dns
topologyKey: failure-domain.beta.kubernetes.io/zone
weight: 10
- podAffinityTerm:
labelSelector:
matchExpressions:
- key: k8s-app
operator: In
values:
- kube-dns
topologyKey: kubernetes.io/hostname
weight: 5
serviceAccountName: coredns
tolerations:
- key: node-role.kubernetes.io/master
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