Support for Kafka Schema registry

I use the Kafka test container which work really well. The only issue that I have is that I use protobuf/avro encoding for my messages. This means I need to run the schema registry container.

Would it be possible to provide the schema registry out of the box and document it in the docs ? I'm willing to create a PR but I prefer to ask first.

See below the definition that I use in my unit test:

public class SchemaRegistryContainer extends GenericContainer<SchemaRegistryContainer> {

  public SchemaRegistryContainer() {
    this("5.5.1");
  }

  public SchemaRegistryContainer(String version) {
    super("confluentinc/cp-schema-registry:" + version);
    withExposedPorts(8081);
  }

  public SchemaRegistryContainer withKafka(KafkaContainer kafka) {
    withEnv("SCHEMA_REGISTRY_HOST_NAME", "schema-registry");
    withEnv("SCHEMA_REGISTRY_LISTENERS", "http://0.0.0.0:8081");
    withEnv(
        "SCHEMA_REGISTRY_KAFKASTORE_BOOTSTRAP_SERVERS",
        "PLAINTEXT://" + kafka.getNetworkAliases().get(0) + ":9092");
    return self();
  }

  public String getSchemaRegistryUrl() {
    return "http://" + getContainerIpAddress() + ":" + getMappedPort(8081);
  }
}

Start by reviewing the KafkaContainer and GenericContainer entry points, then compare the issue's SchemaRegistryContainer example with the project's existing container modules. Done means schema registry support is available for Kafka tests and its usage is documented for protobuf or Avro messages.