Initial commit carried over from private repo. This is V2.

code/MessengerApi.Configuration/Model/Persistence/NpgPersistenceConfiguration.cs

@@ -0,0 +1,20 @@
+using MessengerApi.Configuration.Enums;
+using MessengerApi.Configuration.Model.Persistence.Base;
+using MessengerApi.Configuration.Sources.Environment;
+
+namespace MessengerApi.Configuration.Model.Persistence
+{
+    public class NpgPersistenceConfiguration : PersistenceConfiguration
+    {
+        public override PersistenceTypes PersistenceType => PersistenceTypes.PostgreSql;
+
+        public string ConnectionString { get; }
+
+        public NpgPersistenceConfiguration(string connectionString)
+        {
+            ConnectionString = connectionString;
+        }
+
+        public NpgPersistenceConfiguration(IEnvironmentConfigurationSource config) : this(config.GetValue<string>(Constants.EnvironmentVariables.NPG_CONNECTIONSTRING)) { }
+    }
+}