Change redis client logic and deprecate hosts with addrs in redis conf (

TykTechnologies#2765)

This PR deprecates `hosts` field in redis configuration. Instead `addrs` is defined. Example:
```
"addrs": [
"localhost:30001",
"localhost:30002",
"localhost:30003"
],
```

Also, this PR changes the redis client definition logic. The old version was defining cluster client if given address number is more than one. Otherwise, it was defining a simple redis client.
With this PR, if `enable_cluster` is `true`, the client will be automatically defined as cluster client no matter number of given addresses in config.

Fixes TykTechnologies#2742

cli/linter/schema.json

@@ -32,6 +32,12 @@
             "null"
           ]
         },
+        "addrs": {
+          "type": [
+            "array",
+            "null"
+          ]
+        },
         "optimisation_max_active": {
           "type": "integer"
         },
@@ -1030,8 +1036,8 @@
     "enable_http_profiler": {
       "type": "boolean"
     },
-    "ssl_force_common_name_check":{
-	    "type":"boolean"
+    "ssl_force_common_name_check": {
+      "type": "boolean"
     }
   }
 }

config/config.go

@@ -80,7 +80,8 @@ type StorageOptionsConf struct {
 	Type                  string            `json:"type"`
 	Host                  string            `json:"host"`
 	Port                  int               `json:"port"`
-	Hosts                 map[string]string `json:"hosts"`
+	Hosts                 map[string]string `json:"hosts"` // Deprecated: Addrs instead.
+	Addrs                 []string          `json:"addrs"`
 	Username              string            `json:"username"`
 	Password              string            `json:"password"`
 	Database              int               `json:"database"`

storage/redis_cluster.go

@@ -111,10 +111,6 @@ func NewRedisClusterPool(isCache bool) redis.UniversalClient {
 		poolSize = cfg.MaxActive
 	}
 
-	if cfg.EnableCluster {
-		log.Info("--> Using clustered mode")
-	}
-
 	timeout := 5 * time.Second
 
 	if cfg.Timeout > 0 {
@@ -127,9 +123,13 @@ func NewRedisClusterPool(isCache bool) redis.UniversalClient {
 
 	var seedHosts []string
 
-	for h, p := range cfg.Hosts {
-		addr := h + ":" + p
-		seedHosts = append(seedHosts, addr)
+	if len(cfg.Addrs) != 0 {
+		seedHosts = cfg.Addrs
+	} else {
+		for h, p := range cfg.Hosts {
+			addr := h + ":" + p
+			seedHosts = append(seedHosts, addr)
+		}
 	}
 
 	if len(seedHosts) == 0 {
@@ -145,11 +145,8 @@ func NewRedisClusterPool(isCache bool) redis.UniversalClient {
 		}
 	}
 
-	if !cfg.EnableCluster {
-		seedHosts = seedHosts[:1]
-	}
-
-	client := redis.NewUniversalClient(&redis.UniversalOptions{
+	var client redis.UniversalClient
+	opts := &RedisOpts{
 		Addrs:        seedHosts,
 		Password:     cfg.Password,
 		DB:           cfg.Database,
@@ -159,11 +156,90 @@ func NewRedisClusterPool(isCache bool) redis.UniversalClient {
 		IdleTimeout:  240 * timeout,
 		PoolSize:     poolSize,
 		TLSConfig:    tlsConfig,
-	})
+	}
+
+	if cfg.EnableCluster {
+		log.Info("--> [REDIS] Using clustered mode")
+		client = redis.NewClusterClient(opts.cluster())
+	} else {
+		log.Info("--> [REDIS] Using single node mode")
+		client = redis.NewClient(opts.simple())
+	}
 
 	return client
 }
 
+// RedisOpts is the overriden type of redis.UniversalOptions. simple() and cluster() functions are not public
+// in redis library. Therefore, they are redefined in here to use in creation of new redis cluster logic.
+// We don't want to use redis.NewUniversalClient() logic.
+type RedisOpts redis.UniversalOptions
+
+func (o *RedisOpts) cluster() *redis.ClusterOptions {
+	if len(o.Addrs) == 0 {
+		o.Addrs = []string{"127.0.0.1:6379"}
+	}
+
+	return &redis.ClusterOptions{
+		Addrs:     o.Addrs,
+		OnConnect: o.OnConnect,
+
+		Password: o.Password,
+
+		MaxRedirects:   o.MaxRedirects,
+		ReadOnly:       o.ReadOnly,
+		RouteByLatency: o.RouteByLatency,
+		RouteRandomly:  o.RouteRandomly,
+
+		MaxRetries:      o.MaxRetries,
+		MinRetryBackoff: o.MinRetryBackoff,
+		MaxRetryBackoff: o.MaxRetryBackoff,
+
+		DialTimeout:        o.DialTimeout,
+		ReadTimeout:        o.ReadTimeout,
+		WriteTimeout:       o.WriteTimeout,
+		PoolSize:           o.PoolSize,
+		MinIdleConns:       o.MinIdleConns,
+		MaxConnAge:         o.MaxConnAge,
+		PoolTimeout:        o.PoolTimeout,
+		IdleTimeout:        o.IdleTimeout,
+		IdleCheckFrequency: o.IdleCheckFrequency,
+
+		TLSConfig: o.TLSConfig,
+	}
+}
+
+func (o *RedisOpts) simple() *redis.Options {
+	addr := "127.0.0.1:6379"
+	if len(o.Addrs) > 0 {
+		addr = o.Addrs[0]
+	}
+
+	return &redis.Options{
+		Addr:      addr,
+		OnConnect: o.OnConnect,
+
+		DB:       o.DB,
+		Password: o.Password,
+
+		MaxRetries:      o.MaxRetries,
+		MinRetryBackoff: o.MinRetryBackoff,
+		MaxRetryBackoff: o.MaxRetryBackoff,
+
+		DialTimeout:  o.DialTimeout,
+		ReadTimeout:  o.ReadTimeout,
+		WriteTimeout: o.WriteTimeout,
+
+		PoolSize:           o.PoolSize,
+		MinIdleConns:       o.MinIdleConns,
+		MaxConnAge:         o.MaxConnAge,
+		PoolTimeout:        o.PoolTimeout,
+		IdleTimeout:        o.IdleTimeout,
+		IdleCheckFrequency: o.IdleCheckFrequency,
+
+		TLSConfig: o.TLSConfig,
+	}
+}
+
 // Connect will establish a connection to the r.singleton()
 func (r *RedisCluster) Connect() bool {
 	redisSingletonMu.Lock()