fix: Allow specifying the protocol (TCP, UDP, SCTP) to resolve the public assigned host port

src/Testcontainers/Clients/ContainerConfigurationConverter.cs

@@ -48,7 +48,7 @@ public ContainerConfigurationConverter(IContainerConfiguration configuration)
 
     public IDictionary<string, EndpointSettings> Networks { get; }
 
-    private static string GetQualifiedPort(string containerPort)
+    public static string GetQualifiedPort(string containerPort)
     {
       return Array.Exists(new[] { UdpPortSuffix, TcpPortSuffix, SctpPortSuffix }, portSuffix => containerPort.EndsWith(portSuffix, StringComparison.OrdinalIgnoreCase)) ? containerPort.ToLowerInvariant() : containerPort + TcpPortSuffix;
     }

src/Testcontainers/Containers/DockerContainer.cs

@@ -236,13 +236,15 @@ public ushort GetMappedPublicPort(string containerPort)
     {
       ThrowIfResourceNotFound();
 
-      if (_container.NetworkSettings.Ports.TryGetValue($"{containerPort}/tcp", out var portBindings) && ushort.TryParse(portBindings[0].HostPort, out var publicPort))
+      var qualifiedContainerPort = ContainerConfigurationConverter.GetQualifiedPort(containerPort);
+
+      if (_container.NetworkSettings.Ports.TryGetValue(qualifiedContainerPort, out var portBindings) && ushort.TryParse(portBindings[0].HostPort, out var publicPort))
       {
         return publicPort;
       }
       else
       {
-        throw new InvalidOperationException($"Exposed port {containerPort} is not mapped.");
+        throw new InvalidOperationException($"Exposed port {qualifiedContainerPort} is not mapped.");
       }
     }
 

src/Testcontainers/Containers/IContainer.cs

@@ -132,6 +132,9 @@ public interface IContainer : IAsyncDisposable
     /// <summary>
     /// Resolves the public assigned host port.
     /// </summary>
+    /// <remarks>
+    /// Resolves the public assigned host port for the TCP protocol. To resolve a specific protocol, use <see cref="GetMappedPublicPort(string)" />.
+    /// </remarks>
     /// <param name="containerPort">The container port.</param>
     /// <returns>Returns the public assigned host port.</returns>
     /// <exception cref="InvalidOperationException">Container has not been created.</exception>
@@ -140,6 +143,9 @@ public interface IContainer : IAsyncDisposable
     /// <summary>
     /// Resolves the public assigned host port.
     /// </summary>
+    /// <remarks>
+    /// Append /tcp|udp|sctp to <paramref name="containerPort" /> to resolve the public assigned host port for a specific protocol e.g. "53/udp".
+    /// </remarks>
     /// <param name="containerPort">The container port.</param>
     /// <returns>Returns the public assigned host port.</returns>
     /// <exception cref="InvalidOperationException">Container has not been created.</exception>

tests/Testcontainers.Tests/Unit/Containers/Unix/TestcontainersContainerTest.cs

@@ -171,7 +171,29 @@ await container.StartAsync()
       }
 
       [Fact]
-      public async Task RandomPortBinding()
+      public async Task RandomUdpPortBinding()
+      {
+        // Given
+        const ushort containerPort = 53;
+
+        const string qualifiedContainerPort = "53/udp";
+
+        await using var container = new ContainerBuilder()
+          .WithImage(CommonImages.Alpine)
+          .WithEntrypoint(CommonCommands.SleepInfinity)
+          .WithPortBinding(qualifiedContainerPort, true)
+          .Build();
+
+        // When
+        await container.StartAsync()
+          .ConfigureAwait(true);
+
+        // Then
+        Assert.NotEqual(containerPort, container.GetMappedPublicPort(qualifiedContainerPort));
+      }
+
+      [Fact]
+      public async Task RandomTcpPortBinding()
       {
         // Given
         const ushort containerPort = 80;