diff --git a/src/DotNet.Testcontainers.Tests/DotNet.Testcontainers.Tests.csproj b/src/DotNet.Testcontainers.Tests/DotNet.Testcontainers.Tests.csproj
index cdc992286..69405ed40 100644
--- a/src/DotNet.Testcontainers.Tests/DotNet.Testcontainers.Tests.csproj
+++ b/src/DotNet.Testcontainers.Tests/DotNet.Testcontainers.Tests.csproj
@@ -7,6 +7,7 @@
     <PackageReference Include="coverlet.msbuild" Version="2.5.1" />
     <PackageReference Include="LanguageExt.Core" Version="3.1.15" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.0" />
+    <PackageReference Include="Npgsql" Version="4.0.5" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
     <PackageReference Include="xunit" Version="2.4.1" />
   </ItemGroup>
diff --git a/src/DotNet.Testcontainers.Tests/Unit/DatabaseContainerTest.cs b/src/DotNet.Testcontainers.Tests/Unit/DatabaseContainerTest.cs
index 38db160ea..47ee92506 100644
--- a/src/DotNet.Testcontainers.Tests/Unit/DatabaseContainerTest.cs
+++ b/src/DotNet.Testcontainers.Tests/Unit/DatabaseContainerTest.cs
@@ -3,6 +3,8 @@ namespace DotNet.Testcontainers.Tests.Unit
   using System.Threading.Tasks;
   using DotNet.Testcontainers.Core.Builder;
   using DotNet.Testcontainers.Core.Containers.Database;
+  using DotNet.Testcontainers.Core.Models;
+  using Npgsql;
   using Xunit;
 
   public class DatabaseContainerTest
@@ -10,18 +12,31 @@ public class DatabaseContainerTest
     [Fact]
     public async Task PostgreSqlContainer()
     {
-      var database = string.Empty;
-
-      var username = string.Empty;
-
-      var password = string.Empty;
-
       var testcontainersBuilder = new TestcontainersBuilder<PostgreSqlContainer>()
-        .WithDatabase(database, username, password);
+        .WithDatabase(new DatabaseConfiguration
+        {
+          Database = "db",
+          Username = "postgres",
+          Password = "postgres",
+        });
 
       using (var testcontainer = testcontainersBuilder.Build())
       {
         await testcontainer.StartAsync();
+
+        /*
+        using (var connection = new NpgsqlConnection(testcontainer.ConnectionString))
+        {
+          connection.Open();
+
+          using (var cmd = new NpgsqlCommand())
+          {
+            cmd.Connection = connection;
+            cmd.CommandText = "SELECT 1";
+            cmd.ExecuteReader();
+          }
+        }
+        */
       }
     }
   }
diff --git a/src/DotNet.Testcontainers.Tests/Unit/TestcontainersTest.cs b/src/DotNet.Testcontainers.Tests/Unit/TestcontainersContainerTest.cs
similarity index 99%
rename from src/DotNet.Testcontainers.Tests/Unit/TestcontainersTest.cs
rename to src/DotNet.Testcontainers.Tests/Unit/TestcontainersContainerTest.cs
index 66cbb7f5a..a947a07fa 100644
--- a/src/DotNet.Testcontainers.Tests/Unit/TestcontainersTest.cs
+++ b/src/DotNet.Testcontainers.Tests/Unit/TestcontainersContainerTest.cs
@@ -10,7 +10,7 @@ namespace DotNet.Testcontainers.Tests.Unit
   using Xunit;
   using static LanguageExt.Prelude;
 
-  public static class TestcontainersTest
+  public static class TestcontainersContainerTest
   {
     private static readonly string TempDir = Environment.GetEnvironmentVariable("AGENT_TEMPDIRECTORY") ?? "."; // We cannot use `Path.GetTempPath()` on macOS, see: https://github.com/common-workflow-language/cwltool/issues/328
 
diff --git a/src/DotNet.Testcontainers.Tests/Unit/TestcontainersWaitStrategyTest.cs b/src/DotNet.Testcontainers.Tests/Unit/TestcontainersWaitStrategyTest.cs
index bc395a5a5..1c8a4c33f 100644
--- a/src/DotNet.Testcontainers.Tests/Unit/TestcontainersWaitStrategyTest.cs
+++ b/src/DotNet.Testcontainers.Tests/Unit/TestcontainersWaitStrategyTest.cs
@@ -35,7 +35,7 @@ protected override async Task<bool> Until()
     public class Timeout : WaitStrategy
     {
       [Fact]
-      public async Task WhileAfter5ms()
+      public async Task WhileAfter1ms()
       {
         await Assert.ThrowsAsync<TimeoutException>(async () =>
         {
@@ -44,7 +44,7 @@ await Assert.ThrowsAsync<TimeoutException>(async () =>
       }
 
       [Fact]
-      public async Task UntilAfter5ms()
+      public async Task UntilAfter1ms()
       {
         await Assert.ThrowsAsync<TimeoutException>(async () =>
         {
diff --git a/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilder.cs b/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilder.cs
index bd38f891b..6c73ef465 100644
--- a/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilder.cs
+++ b/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilder.cs
@@ -103,7 +103,7 @@ public ITestcontainersBuilder<T> WithExposedPort(string port)
     {
       return Build(this, new TestcontainersConfiguration
       {
-        Container = new ContainerConfiguration { Labels = new Dictionary<string, string> { { port, port } } },
+        Container = new ContainerConfiguration { ExposedPorts = new Dictionary<string, string> { { port, port } } },
       });
     }
 
diff --git a/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilderExtensions.cs b/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilderExtensions.cs
deleted file mode 100644
index 52b6caebc..000000000
--- a/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilderExtensions.cs
+++ /dev/null
@@ -1,25 +0,0 @@
-namespace DotNet.Testcontainers.Core.Builder
-{
-  using DotNet.Testcontainers.Core.Containers.Database;
-
-  public static class TestcontainersBuilderExtensions
-  {
-    public static ITestcontainersBuilder<T> WithDatabase<T>(this ITestcontainersBuilder<T> builder, string database, string username, string password)
-        where T : PostgreSqlContainer
-    {
-      return builder
-        .WithImage("postgres")
-        .WithCommand("postgres")
-        .WithExposedPort(5432)
-        .WithEnvironment("POSTGRES_DB", database)
-        .WithEnvironment("POSTGRES_USER", username)
-        .WithEnvironment("POSTGRES_PASSWORD", password)
-        .ConfigureContainer((container) =>
-        {
-          container.Database = database;
-          container.Username = username;
-          container.Password = password;
-        });
-    }
-  }
-}
diff --git a/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilderPostgreSqlExtension.cs b/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilderPostgreSqlExtension.cs
new file mode 100644
index 000000000..73ddfd676
--- /dev/null
+++ b/src/DotNet.Testcontainers/Core/Builder/TestcontainersBuilderPostgreSqlExtension.cs
@@ -0,0 +1,37 @@
+namespace DotNet.Testcontainers.Core.Builder
+{
+  using DotNet.Testcontainers.Core.Containers.Database;
+  using DotNet.Testcontainers.Core.Models;
+
+  public static class TestcontainersBuilderPostgreSqlExtension
+  {
+    private const string DefaultImage = "postgres:11.2";
+
+    private const string DefaultPort = "5432";
+
+    private const string Database = "POSTGRES_DB";
+
+    private const string Username = "POSTGRES_USER";
+
+    private const string Password = "POSTGRES_PASSWORD";
+
+    public static ITestcontainersBuilder<T> WithDatabase<T>(this ITestcontainersBuilder<T> builder, DatabaseConfiguration configuration)
+        where T : PostgreSqlContainer
+    {
+      return builder
+        .WithImage(DefaultImage)
+        .WithPortBinding(DefaultPort)
+        .WithEnvironment(Database, configuration.Database)
+        .WithEnvironment(Username, configuration.Username)
+        .WithEnvironment(Password, configuration.Password)
+        .ConfigureContainer((container) =>
+        {
+          container.Hostname = configuration.Hostname;
+          container.Port = configuration.Port;
+          container.Database = configuration.Database;
+          container.Username = configuration.Username;
+          container.Password = configuration.Password;
+        });
+    }
+  }
+}
diff --git a/src/DotNet.Testcontainers/Core/Containers/Database/DatabaseContainer.cs b/src/DotNet.Testcontainers/Core/Containers/Database/DatabaseContainer.cs
index c54771e76..094c49b9f 100644
--- a/src/DotNet.Testcontainers/Core/Containers/Database/DatabaseContainer.cs
+++ b/src/DotNet.Testcontainers/Core/Containers/Database/DatabaseContainer.cs
@@ -5,10 +5,14 @@ namespace DotNet.Testcontainers.Core.Containers.Database
 
   public abstract class DatabaseContainer : TestcontainersContainer
   {
-    internal DatabaseContainer(TestcontainersConfiguration configuration) : base(configuration)
+    protected DatabaseContainer(TestcontainersConfiguration configuration) : base(configuration)
     {
     }
 
+    public virtual string Hostname { get; set; }
+
+    public virtual string Port { get; set; }
+
     public virtual string Database { get; set; }
 
     public virtual string Username { get; set; }
diff --git a/src/DotNet.Testcontainers/Core/Containers/Database/PostgreSqlContainer.cs b/src/DotNet.Testcontainers/Core/Containers/Database/PostgreSqlContainer.cs
index 152acbfb3..3315b284d 100644
--- a/src/DotNet.Testcontainers/Core/Containers/Database/PostgreSqlContainer.cs
+++ b/src/DotNet.Testcontainers/Core/Containers/Database/PostgreSqlContainer.cs
@@ -8,6 +8,6 @@ internal PostgreSqlContainer(TestcontainersConfiguration configuration) : base(c
     {
     }
 
-    public override string ConnectionString => $"Server=127.0.0.1;Port=5432;Database={this.Database};User Id={this.Username};Password={this.Password};";
+    public override string ConnectionString => $"Server={this.Hostname};Port={this.Port};Database={this.Database};User Id={this.Username};Password={this.Password};";
   }
 }
diff --git a/src/DotNet.Testcontainers/Core/Containers/TestcontainersContainer.cs b/src/DotNet.Testcontainers/Core/Containers/TestcontainersContainer.cs
index 5b66c1aff..22729d92a 100644
--- a/src/DotNet.Testcontainers/Core/Containers/TestcontainersContainer.cs
+++ b/src/DotNet.Testcontainers/Core/Containers/TestcontainersContainer.cs
@@ -19,7 +19,7 @@ public class TestcontainersContainer : IDockerContainer
 
     private Option<ContainerListResponse> container = None;
 
-    internal TestcontainersContainer(TestcontainersConfiguration configuration)
+    protected TestcontainersContainer(TestcontainersConfiguration configuration)
     {
       this.Configuration = configuration;
     }
diff --git a/src/DotNet.Testcontainers/Core/Mapper/TestcontainersConfigurationConverter.cs b/src/DotNet.Testcontainers/Core/Mapper/TestcontainersConfigurationConverter.cs
index a5cd94e89..8ed19fe70 100644
--- a/src/DotNet.Testcontainers/Core/Mapper/TestcontainersConfigurationConverter.cs
+++ b/src/DotNet.Testcontainers/Core/Mapper/TestcontainersConfigurationConverter.cs
@@ -33,7 +33,7 @@ private class ToList : CollectionConverter<IList<string>>
     {
       public override IList<string> Convert(IReadOnlyCollection<string> source)
       {
-        return source.ToList();
+        return source?.ToList();
       }
     }
 
@@ -41,7 +41,7 @@ private class ToDictionary : DictionaryConverter<IDictionary<string, string>>
     {
       public override IDictionary<string, string> Convert(IReadOnlyDictionary<string, string> source)
       {
-        return source.ToDictionary(item => item.Key, item => item.Value);
+        return source?.ToDictionary(item => item.Key, item => item.Value);
       }
     }
 
@@ -49,7 +49,7 @@ private class ToMappedList : DictionaryConverter<IList<string>>
     {
       public override IList<string> Convert(IReadOnlyDictionary<string, string> source)
       {
-        return source.Select(item => $"{item.Key}={item.Value}").ToList();
+        return source?.Select(item => $"{item.Key}={item.Value}").ToList();
       }
     }
 
@@ -61,7 +61,7 @@ public ToExposedPorts() : base("ExposedPorts")
 
       public override IDictionary<string, EmptyStruct> Convert(IReadOnlyDictionary<string, string> source)
       {
-        return source.ToDictionary(exposedPort => $"{exposedPort.Key}/tcp", exposedPort => default(EmptyStruct));
+        return source?.ToDictionary(exposedPort => $"{exposedPort.Key}/tcp", exposedPort => default(EmptyStruct));
       }
     }
 
@@ -73,7 +73,7 @@ public ToPortBindings() : base("PortBindings")
 
       public override IDictionary<string, IList<PortBinding>> Convert(IReadOnlyDictionary<string, string> source)
       {
-        return source.ToDictionary(binding => $"{binding.Value}/tcp", binding => new List<PortBinding> { new PortBinding { HostPort = binding.Key } } as IList<PortBinding>);
+        return source?.ToDictionary(binding => $"{binding.Value}/tcp", binding => new List<PortBinding> { new PortBinding { HostPort = binding.Key } } as IList<PortBinding>);
       }
     }
 
@@ -85,7 +85,7 @@ public ToMounts() : base("Mounts")
 
       public override IList<Mount> Convert(IReadOnlyDictionary<string, string> source)
       {
-        return source.Select(mount => new Mount { Source = Path.GetFullPath(mount.Key), Target = mount.Value, Type = "bind" }).ToList();
+        return source?.Select(mount => new Mount { Source = Path.GetFullPath(mount.Key), Target = mount.Value, Type = "bind" }).ToList();
       }
     }
   }
diff --git a/src/DotNet.Testcontainers/Core/Models/DatabaseConfiguration.cs b/src/DotNet.Testcontainers/Core/Models/DatabaseConfiguration.cs
new file mode 100644
index 000000000..2b9b0f921
--- /dev/null
+++ b/src/DotNet.Testcontainers/Core/Models/DatabaseConfiguration.cs
@@ -0,0 +1,15 @@
+namespace DotNet.Testcontainers.Core.Models
+{
+  public class DatabaseConfiguration
+  {
+    public virtual string Hostname { get; set; } = "localhost";
+
+    public virtual string Port { get; set; }
+
+    public virtual string Database { get; set; }
+
+    public virtual string Username { get; set; }
+
+    public virtual string Password { get; set; }
+  }
+}
diff --git a/src/DotNet.Testcontainers/Core/Models/TestcontainersConfiguration.cs b/src/DotNet.Testcontainers/Core/Models/TestcontainersConfiguration.cs
index c5729ecf8..7013a8be9 100644
--- a/src/DotNet.Testcontainers/Core/Models/TestcontainersConfiguration.cs
+++ b/src/DotNet.Testcontainers/Core/Models/TestcontainersConfiguration.cs
@@ -5,7 +5,7 @@ namespace DotNet.Testcontainers.Core.Models
   using System.Linq;
   using DotNet.Testcontainers.Diagnostics;
 
-  internal class TestcontainersConfiguration
+  public class TestcontainersConfiguration
   {
     public ContainerConfiguration Container { get; set; } = new ContainerConfiguration();
 
@@ -39,7 +39,7 @@ internal TestcontainersConfiguration Merge(TestcontainersConfiguration old)
 
       this.Host.Mounts = Merge(this.Host.Mounts, old.Host.Mounts);
 
-      this.CleanUp = old.CleanUp;
+      this.CleanUp = this.CleanUp && old.CleanUp;
 
       this.OutputConsumer = Merge(this.OutputConsumer, old.OutputConsumer);
 
@@ -57,22 +57,22 @@ private static T Merge<T>(T myself, T old)
     private static IReadOnlyCollection<T> Merge<T>(IReadOnlyCollection<T> myself, IReadOnlyCollection<T> old)
       where T : class
     {
-      if (myself == null)
+      if (myself == null || old == null)
       {
-        return old ?? new ReadOnlyCollection<T>(new List<T>());
+        return myself ?? old;
       }
       else
       {
-        return myself.Concat(old.Where(x => !myself.Contains(x))).ToList();
+        return myself.Concat(old).ToList();
       }
     }
 
     private static IReadOnlyDictionary<T, T> Merge<T>(IReadOnlyDictionary<T, T> myself, IReadOnlyDictionary<T, T> old)
       where T : class
     {
-      if (myself == null)
+      if (myself == null || old == null)
       {
-        return old ?? new ReadOnlyDictionary<T, T>(new Dictionary<T, T>());
+        return myself ?? old;
       }
       else
       {
@@ -88,22 +88,22 @@ public class ContainerConfiguration
 
       public string WorkingDirectory { get; set; }
 
-      public IReadOnlyCollection<string> Entrypoint { get; set; } = new List<string>();
+      public IReadOnlyCollection<string> Entrypoint { get; set; }
 
-      public IReadOnlyCollection<string> Command { get; set; } = new List<string>();
+      public IReadOnlyCollection<string> Command { get; set; }
 
-      public IReadOnlyDictionary<string, string> Environments { get; set; } = new Dictionary<string, string>();
+      public IReadOnlyDictionary<string, string> Environments { get; set; }
 
-      public IReadOnlyDictionary<string, string> Labels { get; set; } = new Dictionary<string, string>();
+      public IReadOnlyDictionary<string, string> Labels { get; set; }
 
-      public IReadOnlyDictionary<string, string> ExposedPorts { get; set; } = new Dictionary<string, string>();
+      public IReadOnlyDictionary<string, string> ExposedPorts { get; set; }
     }
 
     public class HostConfiguration
     {
-      public IReadOnlyDictionary<string, string> PortBindings { get; set; } = new Dictionary<string, string>();
+      public IReadOnlyDictionary<string, string> PortBindings { get; set; }
 
-      public IReadOnlyDictionary<string, string> Mounts { get; set; } = new Dictionary<string, string>();
+      public IReadOnlyDictionary<string, string> Mounts { get; set; }
     }
   }
 }