Merge pull request #61210 from hzxuzhonghu/etcd-random-check

Automatic merge from submit-queue. 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>. check etcd servers by a random order **What this PR does / why we need it**: Every time a health check is called on the APIServer via the /healthz endpoint, an etcd healthcheck is performed. Here makes servers check with a random order. **Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*: Fixes #61180 **Special notes for your reviewer**: **Release note**: ```release-note NONE ```

Merge pull request #61210 from hzxuzhonghu/etcd-random-check
a0a742c3 · Kubernetes Submit Queue · GitHub · 3e4268f5 · fffa4055 · a0a742c3
Unverified Commit a0a742c3 authored Apr 13, 2018 by Kubernetes Submit Queue Committed by GitHub Apr 13, 2018
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Showing with 6 additions and 9 deletions

checks.go ...rc/k8s.io/apiserver/pkg/storage/etcd3/preflight/checks.go +6 -9

No files found.
--- a/staging/src/k8s.io/apiserver/pkg/storage/etcd3/preflight/checks.go
+++ b/staging/src/k8s.io/apiserver/pkg/storage/etcd3/preflight/checks.go
@@ -18,6 +18,7 @@ package preflight

 import (
 	"fmt"
+	"math/rand"
 	"net"
 	"net/url"
 	"time"
@@ -25,12 +26,6 @@ import (

 const connectionTimeout = 1 * time.Second

-type connection interface {
-	serverReachable(address string) bool
-	parseServerList(serverList []string) error
-	CheckEtcdServers() (bool, error)
-}
-
 // EtcdConnection holds the Etcd server list
 type EtcdConnection struct {
 	ServerList []string
@@ -59,9 +54,11 @@ func parseServerURI(serverURI string) (*url.URL, error) {
 // CheckEtcdServers will attempt to reach all etcd servers once. If any
 // can be reached, return true.
 func (con EtcdConnection) CheckEtcdServers() (done bool, err error) {
-	// Attempt to reach every Etcd server in order
-	for _, serverURI := range con.ServerList {
-		host, err := parseServerURI(serverURI)
+	// Attempt to reach every Etcd server randomly.
+	serverNumber := len(con.ServerList)
+	serverPerms := rand.Perm(serverNumber)
+	for _, index := range serverPerms {
+		host, err := parseServerURI(con.ServerList[index])
 		if err != nil {
 			return false, err
 		}