net/redisclient: fix nil pointer dereference (#2939)

Fix use of logger before initialization.

Followup on #2261

Signed-off-by: Alexander Yastrebov <alexander.yastrebov@zalando.de>

net/redisclient.go

@@ -222,6 +222,10 @@ func NewRedisRingClient(ro *RedisOptions) *RedisRingClient {
 			ringOptions.NewConsistentHash = NewMultiprobe
 		}
 
+		if ro.Log == nil {
+			ro.Log = &logging.DefaultLog{}
+		}
+
 		if ro.AddrUpdater != nil {
 			address, err := ro.AddrUpdater()
 			for i := 0; i < retryCount; i++ {
@@ -232,16 +236,15 @@ func NewRedisRingClient(ro *RedisOptions) *RedisRingClient {
 				address, err = ro.AddrUpdater()
 			}
 			if err != nil {
-				r.log.Errorf("Failed at redisclient startup %v", err)
+				ro.Log.Errorf("Failed at redisclient startup %v", err)
 			}
 			ringOptions.Addrs = createAddressMap(address)
 		} else {
 			ringOptions.Addrs = createAddressMap(ro.Addrs)
 		}
-		if ro.Log == nil {
-			ro.Log = &logging.DefaultLog{}
-		}
-		ro.Log.Infof("create ring with addresses: %v", ro.Addrs)
+
+		ro.Log.Infof("Created ring with addresses: %v", ro.Addrs)
+
 		ringOptions.ReadTimeout = ro.ReadTimeout
 		ringOptions.WriteTimeout = ro.WriteTimeout
 		ringOptions.PoolTimeout = ro.PoolTimeout

net/redisclient_test.go

@@ -2,6 +2,7 @@ package net
 
 import (
 	"context"
+	"fmt"
 	"sync"
 	"testing"
 	"time"
@@ -1084,3 +1085,17 @@ func TestRedisClientSetAddr(t *testing.T) {
 		})
 	}
 }
+
+func TestRedisClientFailingAddrUpdater(t *testing.T) {
+	cli := NewRedisRingClient(&RedisOptions{
+		AddrUpdater: func() ([]string, error) {
+			return nil, fmt.Errorf("failed to get addresses")
+		},
+		UpdateInterval: 1 * time.Second,
+	})
+	defer cli.Close()
+
+	if cli.RingAvailable() {
+		t.Error("Unexpected available ring")
+	}
+}