Alerting: Add support for running HA using Redis (#65267)

Co-authored-by: Steve Simpson <steve.simpson@grafana.com>

pkg/setting/setting_unified_alerting.go

@@ -71,6 +71,12 @@ type UnifiedAlertingSettings struct {
 	HAPeerTimeout                  time.Duration
 	HAGossipInterval               time.Duration
 	HAPushPullInterval             time.Duration
+	HARedisAddr                    string
+	HARedisPeerName                string
+	HARedisPrefix                  string
+	HARedisUsername                string
+	HARedisPassword                string
+	HARedisDB                      int
 	MaxAttempts                    int64
 	MinInterval                    time.Duration
 	EvaluationTimeout              time.Duration
@@ -224,6 +230,12 @@ func (cfg *Cfg) ReadUnifiedAlertingSettings(iniFile *ini.File) error {
 	}
 	uaCfg.HAListenAddr = ua.Key("ha_listen_address").MustString(alertmanagerDefaultClusterAddr)
 	uaCfg.HAAdvertiseAddr = ua.Key("ha_advertise_address").MustString("")
+	uaCfg.HARedisAddr = ua.Key("ha_redis_address").MustString("")
+	uaCfg.HARedisPeerName = ua.Key("ha_redis_peer_name").MustString("")
+	uaCfg.HARedisPrefix = ua.Key("ha_redis_prefix").MustString("")
+	uaCfg.HARedisUsername = ua.Key("ha_redis_username").MustString("")
+	uaCfg.HARedisPassword = ua.Key("ha_redis_password").MustString("")
+	uaCfg.HARedisDB = ua.Key("ha_redis_db").MustInt(0)
 	peers := ua.Key("ha_peers").MustString("")
 	uaCfg.HAPeers = make([]string, 0)
 	if peers != "" {