Merge pull request #52193 from StevenACoffman/kube-dns-anti-affinity

Automatic merge from submit-queue (batch tested with PRs 53106, 52193, 51250, 52449, 53861). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>. kube-dns-anti-affinity: kube-dns never-co-located-in-the-same-node **What this PR does / why we need it**: This is upstreaming the kubernetes/kops#2705 pull request by @jamesbucher that was originally against [kops](github.com/kubernetes/kops). Please see kubernetes/kops#2705 for more details, including a lengthy discussion. Briefly, given the constraints of how the system works today: + if you need multiple DNS pods primarily for availability, then requiredDuringSchedulingIgnoredDuringExecution makes sense because putting more than one DNS pod on the same node isn't useful + if you need multiple DNS pods primarily for performance, then preferredDuringScheduling IgnoredDuringExecution makes sense because it will allow the DNS pods to schedule even if they can't be spread across nodes **Which issue this PR fixes** fixes kubernetes/kops#2693 **Release note**: ```release-note Improve resilience by annotating kube-dns addon with podAntiAffinity to prefer scheduling on different nodes. ```

Merge pull request #52193 from StevenACoffman/kube-dns-anti-affinity
ef874829 · Kubernetes Submit Queue · GitHub · 27b35602 · e6540d42 · ef874829
Commit ef874829 authored Oct 16, 2017 by Kubernetes Submit Queue Committed by GitHub Oct 16, 2017
Showing with 33 additions and 0 deletions

kube-dns.yaml.base cluster/addons/dns/kube-dns.yaml.base +11 -0

kube-dns.yaml.in cluster/addons/dns/kube-dns.yaml.in +11 -0

kube-dns.yaml.sed cluster/addons/dns/kube-dns.yaml.sed +11 -0

No files found.
--- a/cluster/addons/dns/kube-dns.yaml.base
+++ b/cluster/addons/dns/kube-dns.yaml.base
@@ -84,6 +84,17 @@ spec:
      annotations:
        scheduler.alpha.kubernetes.io/critical-pod: ''
    spec:
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+          - weight: 100
+            podAffinityTerm:
+              labelSelector:
+                matchExpressions:
+                  - key: k8s-app
+                    operator: In
+                    values: ["kube-dns"]
+              topologyKey: kubernetes.io/hostname
      tolerations:
      - key: "CriticalAddonsOnly"
        operator: "Exists"

--- a/cluster/addons/dns/kube-dns.yaml.in
+++ b/cluster/addons/dns/kube-dns.yaml.in
@@ -84,6 +84,17 @@ spec:
      annotations:
        scheduler.alpha.kubernetes.io/critical-pod: ''
    spec:
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+          - weight: 100
+            podAffinityTerm:
+              labelSelector:
+                matchExpressions:
+                  - key: k8s-app
+                    operator: In
+                    values: ["kube-dns"]
+              topologyKey: kubernetes.io/hostname
      tolerations:
      - key: "CriticalAddonsOnly"
        operator: "Exists"

--- a/cluster/addons/dns/kube-dns.yaml.sed
+++ b/cluster/addons/dns/kube-dns.yaml.sed
@@ -84,6 +84,17 @@ spec:
      annotations:
        scheduler.alpha.kubernetes.io/critical-pod: ''
    spec:
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+          - weight: 100
+            podAffinityTerm:
+              labelSelector:
+                matchExpressions:
+                  - key: k8s-app
+                    operator: In
+                    values: ["kube-dns"]
+              topologyKey: kubernetes.io/hostname
      tolerations:
      - key: "CriticalAddonsOnly"
        operator: "Exists"