From e3a5468227a4cb44f61888e2a177975e38cf3cf4 Mon Sep 17 00:00:00 2001
From: Eric <cu.eric.lee@gmail.com>
Date: Fri, 14 Jan 2022 22:18:23 +0800
Subject: [PATCH] preferred cause single node failure of coredns (#260)

preferredDuringSchedulingIgnoredDuringExecution cause single node failure in mostly deployment when increasing node one by one by cluster. In most deployment, when one node running coredns is lost, coredns service is outage at least 5mins.Suggest to use **requiredDuringSchedulingIgnoredDuringExecution** instead to avoid single node failure issue.

Signed-off-by: Eric <cu.eric.lee@gmail.com>
---
 kubernetes/coredns.yaml.sed | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/kubernetes/coredns.yaml.sed b/kubernetes/coredns.yaml.sed
index e12813b..4910c04 100644
--- a/kubernetes/coredns.yaml.sed
+++ b/kubernetes/coredns.yaml.sed
@@ -105,15 +105,13 @@ spec:
         kubernetes.io/os: linux
       affinity:
          podAntiAffinity:
-           preferredDuringSchedulingIgnoredDuringExecution:
-           - weight: 100
-             podAffinityTerm:
-               labelSelector:
-                 matchExpressions:
-                   - key: k8s-app
-                     operator: In
-                     values: ["kube-dns"]
-               topologyKey: kubernetes.io/hostname
+           requiredDuringSchedulingIgnoredDuringExecution:
+           - labelSelector:
+               matchExpressions:
+               - key: k8s-app
+                 operator: In
+                 values: ["kube-dns"]
+             topologyKey: kubernetes.io/hostname
       containers:
       - name: coredns
         image: coredns/coredns:1.8.6