Support for multiple servers

src/NLog.Redis.Tests/IntegrationTests/RedisTargetTestsBase.cs

@@ -11,8 +11,7 @@ namespace NLog.Redis.Tests.IntegrationTests
     public abstract class RedisTargetTestsBase
     {
         protected const string RedisKey = "testkey";
-        protected const string RedisHost = "localhost";
-        protected const int RedisPort = 6379;
+        protected const string RedisHosts = "localhost:6379";
         protected const string RedisPassword = "testingpassword";
         protected string Password = null;
 
@@ -36,8 +35,7 @@ public void NLogRedisConfiguration(string dataType, bool usePassword = false)
 
             // set target properties
             redisTarget.Layout = "${uppercase:${level}} ${message}";
-            redisTarget.Host = RedisHost;
-            redisTarget.Port = RedisPort;
+            redisTarget.Hosts = RedisHosts;
             redisTarget.Key = RedisKey;
             redisTarget.Db = 0;
             redisTarget.DataType = dataType;
@@ -62,7 +60,8 @@ public ConnectionMultiplexer GetRedisConnection(bool usePassword = false)
             };
             if (usePassword) connectionOptions.Password = RedisPassword;
 
-            connectionOptions.EndPoints.Add(RedisHost, RedisPort);
+            foreach(var host in RedisHosts.Split(','))
+                connectionOptions.EndPoints.Add(host);
 
             return ConnectionMultiplexer.Connect(connectionOptions);
         }

src/NLog.Redis/RedisConnectionManager.cs

@@ -1,21 +1,31 @@
 using System;
 using StackExchange.Redis;
+using System.Collections.Generic;
 
 namespace NLog.Targets
 {
     internal class RedisConnectionManager : IDisposable
     {
         private ConnectionMultiplexer _connectionMultiplexer;
 
-        private readonly string _host;
-        private readonly int _port;
+        private readonly List<string> _hosts;
         private readonly int _db;
         private readonly string _password;
 
+        public RedisConnectionManager(List<string> hosts, int db, string password)
+        {
+            _hosts = hosts;
+            _db = db;
+            _password = password;
+
+            InitializeConnection();
+        }
+
+        [Obsolete("Use constructor with hosts instead")]
         public RedisConnectionManager(string host, int port, int db, string password)
         {
-            _host = host;
-            _port = port;
+            _hosts = new List<string>();
+            _hosts.Add($"{host}:{port}");
             _db = db;
             _password = password;
 
@@ -32,7 +42,10 @@ private void InitializeConnection()
                     ConnectRetry = 3,
                     KeepAlive = 5
                 };
-            connectionOptions.EndPoints.Add(_host, _port);
+            foreach (var host in _hosts)
+            {
+                connectionOptions.EndPoints.Add(host);
+            }
 
             if (!string.IsNullOrEmpty(_password))
             {

src/NLog.Redis/RedisTarget.cs

@@ -1,5 +1,6 @@
 using System;
 using NLog.Config;
+using System.Linq;
 using NLog.Layouts;
 
 namespace NLog.Targets
@@ -13,15 +14,20 @@ public class RedisTarget : TargetWithLayout
         /// <summary>
         /// Sets the host name or IP Address of the redis server
         /// </summary>
-        [RequiredParameter]
+        [Obsolete("Use hosts instead")]
         public string Host { get; set; }
 
         /// <summary>
         /// Sets the port number redis is running on
         /// </summary>
-        [RequiredParameter]
+        [Obsolete("Use hosts instead")]
         public int Port { get; set; }
 
+        /// <summary>
+        /// Sets the hosts names or IP Addresses and ports of the redis servers
+        /// </summary>
+        public string Hosts { get; set; }
+
         /// <summary>
         /// Sets the key to be used for either the list or the pub/sub channel in redis
         /// </summary>
@@ -69,7 +75,12 @@ protected override void InitializeTarget()
         {
             base.InitializeTarget();
             _dataTypeToLower = DataType?.ToLower();
-            _redisConnectionManager = new RedisConnectionManager(Host, Port, Db, Password);
+            if (!string.IsNullOrWhiteSpace(Host))
+                _redisConnectionManager = new RedisConnectionManager(Host, Port, Db, Password);
+            else if (!string.IsNullOrWhiteSpace(Hosts))
+                _redisConnectionManager = new RedisConnectionManager(Hosts.Split(',').ToList(), Db, Password);
+            else
+                throw new ArgumentException("At least a host must be set");
         }
 
         protected override void CloseTarget()
@@ -99,5 +110,5 @@ protected override void Write(LogEventInfo logEvent)
                     throw new Exception("no data type defined for redis");
             }
         }
-    }
-}
+            }
+        }