Method of exposing UDP port changed in 1.16.0

I am upgrading from: TestContainers 1.15.3 -> 1.16.2 Docker-Java 3.2.8 -> 3.2.12

In order to expose a UDP port, users are required to access the underlying docker-java command, and modify it to expose the desired port. In my project I am doing this using a custom container class and overwriting the configure() method as follows:

public class KerberosContainer extends GenericContainer<KerberosContainer> {
    @Override
    protected void configure() {
        withExposedPorts(99, 464, 749); //TCP ports
        withNetworkAliases(KRB5_KDC);
        withCreateContainerCmdModifier(cmd -> {
            List<ExposedPort> ports = new ArrayList<>();
            for (ExposedPort p : cmd.getExposedPorts()) {
                ports.add(p);
            }
            ports.add(new ExposedPort(99, InternetProtocol.UDP));
            cmd.withExposedPorts(ports);
	    cmd.withHostName(KRB5_KDC);
        });
    }
}

Once the container is started, I try to extract the mapped port using the InspectContainerResponse object as follows:

    @Override
    protected void containerIsStarted(InspectContainerResponse containerInfo) {
        NetworkSettings networkSettings = containerInfo.getNetworkSettings();
        Ports ports = networkSettings.getPorts();
        Map<ExposedPort, Binding[]> map = ports.getBindings();
        Binding[] bindings = map.get(new ExposedPort(99, InternetProtocol.UDP));
        Binding binding = bindings[0];  //NullPointerException
        String udp99 = binding.getHostPortSpec();

        udp_99 = Integer.valueOf(udp99);
    }

A NullPointerException is thrown because the withCreateContainerCmdModifier was not honored. This is apparent when inspecting the container created directly with docker:

And printing out the contents of the bindings map at runtime

{
  749/tcp=[Lcom.github.dockerjava.api.model.Ports$Binding;@3bcb01f9, 
  464/tcp=[Lcom.github.dockerjava.api.model.Ports$Binding;@defb0e3a, 
  99/tcp=[Lcom.github.dockerjava.api.model.Ports$Binding;@15c64f5f, 
  99/udp=null, 
  88/tcp=null
}

[bsideup]

Putting “wontfix” here because it isn’t a breaking change but an assumption that got changed. We never guaranteed that we will bind ports that were added through withCreateContainerCmdModifier and going that route means that now you are dealing with Docker’s low level API and need to understand how it behaves.

[kiview]

Thanks @KyleAure, your help is much appreciated 🙌