Add getMappedPort(int, InternetProtocol) for UDP port lookups

core/src/main/java/org/testcontainers/containers/ContainerState.java

@@ -158,6 +158,24 @@ default Integer getFirstMappedPort() {
      * @see #getCurrentContainerInfo()
      */
     default Integer getMappedPort(int originalPort) {
+        return getMappedPort(originalPort, InternetProtocol.TCP);
+    }
+
+    /**
+     * Get the actual mapped port for a given port exposed by the container, for a specific protocol.
+     * It should be used in conjunction with {@link #getHost()}.
+     * <p>
+     * Note: The returned port number might be outdated (for instance, after disconnecting from a network and reconnecting
+     * again). If you always need up-to-date value, override the {@link #getContainerInfo()} to return the
+     * {@link #getCurrentContainerInfo()}.
+     *
+     * @param originalPort the original port that is exposed
+     * @param protocol the protocol (TCP or UDP) that the port is exposed with
+     * @return the port that the exposed port is mapped to, or null if it is not exposed
+     * @see #getContainerInfo()
+     * @see #getCurrentContainerInfo()
+     */
+    default Integer getMappedPort(int originalPort, InternetProtocol protocol) {
         Preconditions.checkState(
             this.getContainerId() != null,
             "Mapped port can only be obtained after the container is started"
@@ -166,13 +184,17 @@ default Integer getMappedPort(int originalPort) {
         Ports.Binding[] binding = new Ports.Binding[0];
         final InspectContainerResponse containerInfo = this.getContainerInfo();
         if (containerInfo != null) {
-            binding = containerInfo.getNetworkSettings().getPorts().getBindings().get(new ExposedPort(originalPort));
+            ExposedPort exposedPort = new ExposedPort(
+                originalPort,
+                com.github.dockerjava.api.model.InternetProtocol.parse(protocol.name())
+            );
+            binding = containerInfo.getNetworkSettings().getPorts().getBindings().get(exposedPort);
         }
 
         if (binding != null && binding.length > 0 && binding[0] != null) {
             return Integer.valueOf(binding[0].getHostPortSpec());
         } else {
-            throw new IllegalArgumentException("Requested port (" + originalPort + ") is not mapped");
+            throw new IllegalArgumentException("Requested port (" + originalPort + "/" + protocol.toDockerNotation() + ") is not mapped");
         }
     }
 

core/src/main/java/org/testcontainers/containers/GenericContainer.java

@@ -1048,6 +1048,30 @@ public void addExposedPorts(int... ports) {
         this.containerDef.addExposedTcpPorts(ports);
     }
 
+    /**
+     * Expose a container port using a specific protocol, so that a randomly chosen host port will be bound to it
+     * when the container starts. Use {@link ContainerState#getMappedPort(int, InternetProtocol)} to retrieve the
+     * bound host port once the container is running.
+     *
+     * @param port the container port to expose
+     * @param protocol the protocol (TCP or UDP) that the port should be exposed with
+     */
+    public void addExposedPort(int port, InternetProtocol protocol) {
+        this.containerDef.addExposedPort(port, com.github.dockerjava.api.model.InternetProtocol.parse(protocol.name()));
+    }
+
+    /**
+     * Fluent variant of {@link #addExposedPort(int, InternetProtocol)}.
+     *
+     * @param port the container port to expose
+     * @param protocol the protocol (TCP or UDP) that the port should be exposed with
+     * @return this
+     */
+    public SELF withExposedPort(int port, InternetProtocol protocol) {
+        addExposedPort(port, protocol);
+        return self();
+    }
+
     /**
      * {@inheritDoc}
      */

core/src/test/java/org/testcontainers/containers/ContainerStateTest.java

@@ -1,12 +1,20 @@
 package org.testcontainers.containers;
 
+import com.github.dockerjava.api.command.InspectContainerResponse;
+import com.github.dockerjava.api.model.ExposedPort;
+import com.github.dockerjava.api.model.Ports;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.mockito.Answers;
+import org.mockito.Mockito;
 
 import java.util.Collections;
 import java.util.List;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.Mockito.doCallRealMethod;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -35,4 +43,37 @@ void test(String name, String testSet, List<Integer> expectedResult) {
         List<Integer> result = containerState.getBoundPortNumbers();
         assertThat(result).hasSameElementsAs(expectedResult);
     }
+
+    @Test
+    void getMappedPortWithProtocolLooksUpTheBindingForThatProtocol() {
+        ContainerState containerState = mock(ContainerState.class);
+        doCallRealMethod().when(containerState).getMappedPort(anyInt(), any());
+        when(containerState.getContainerId()).thenReturn("container-id");
+
+        InspectContainerResponse containerInfo = Mockito.mock(InspectContainerResponse.class, Answers.RETURNS_DEEP_STUBS);
+        ExposedPort udpPort = new ExposedPort(12345, com.github.dockerjava.api.model.InternetProtocol.UDP);
+        when(containerInfo.getNetworkSettings().getPorts().getBindings())
+            .thenReturn(Collections.singletonMap(udpPort, new Ports.Binding[] { Ports.Binding.bindPort(54321) }));
+        when(containerState.getContainerInfo()).thenReturn(containerInfo);
+
+        Integer mappedPort = containerState.getMappedPort(12345, InternetProtocol.UDP);
+
+        assertThat(mappedPort).isEqualTo(54321);
+    }
+
+    @Test
+    void getMappedPortWithProtocolThrowsWhenNotMapped() {
+        ContainerState containerState = mock(ContainerState.class);
+        doCallRealMethod().when(containerState).getMappedPort(anyInt(), any());
+        when(containerState.getContainerId()).thenReturn("container-id");
+
+        InspectContainerResponse containerInfo = Mockito.mock(InspectContainerResponse.class, Answers.RETURNS_DEEP_STUBS);
+        when(containerInfo.getNetworkSettings().getPorts().getBindings()).thenReturn(Collections.emptyMap());
+        when(containerState.getContainerInfo()).thenReturn(containerInfo);
+
+        org.assertj.core.api.Assertions
+            .assertThatThrownBy(() -> containerState.getMappedPort(12345, InternetProtocol.UDP))
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessageContaining("12345/udp");
+    }
 }