Error and connection reset by peer when trying to run against RedPanda

Running both redpanda and karapace (registry) in docker, I get this in the logs and the schema registry always returns "reset by peer":

023-12-27 11:06:34 karapace.schema_reader      schema-reader   ERROR           Unexpected exception when reading begin offsets.
2023-12-27 11:06:34 Traceback (most recent call last):
2023-12-27 11:06:34   File "/venv/lib/python3.10/site-packages/karapace/kafka/consumer.py", line 61, in get_watermark_offsets
2023-12-27 11:06:34     result = super().get_watermark_offsets(partition, cached=cached)
2023-12-27 11:06:34 cimpl.KafkaException: KafkaError{code=OFFSET_NOT_AVAILABLE,val=78,str="Failed to get watermark offsets: Broker: Leader high watermark is not caught up"}
2023-12-27 11:06:34 
2023-12-27 11:06:34 The above exception was the direct cause of the following exception:
2023-12-27 11:06:34 
2023-12-27 11:06:34 Traceback (most recent call last):
2023-12-27 11:06:34   File "/venv/lib/python3.10/site-packages/karapace/schema_reader.py", line 234, in _get_beginning_offset
2023-12-27 11:06:34     beginning_offset, _ = self.consumer.get_watermark_offsets(TopicPartition(self.config["topic_name"], 0))
2023-12-27 11:06:34   File "/venv/lib/python3.10/site-packages/karapace/kafka/consumer.py", line 68, in get_watermark_offsets
2023-12-27 11:06:34     raise_from_kafkaexception(exc)
2023-12-27 11:06:34   File "/venv/lib/python3.10/site-packages/karapace/kafka/common.py", line 62, in raise_from_kafkaexception
2023-12-27 11:06:34     raise translate_from_kafkaerror(exc.args[0]) from exc
2023-12-27 11:06:34 kafka.errors.UnknownError: [Error -1] UnknownError

Using the latest docker version, with the following environment variables:

        {"KARAPACE_ADVERTISED_HOSTNAME", "karapace-registry"},
        {"KARAPACE_ADVERTISED_PORT", "18881"},
        {"KARAPACE_BOOTSTRAP_URI", "redpanda-0:9092"},
        {"KARAPACE_PORT", "18881"},
        {"KARAPACE_REGISTRY_PORT", "18881"},
        {"KARAPACE_REST", "false"},
        {"KARAPACE_TOPIC_NAME", "_karapace_schemas"},

Trying to avoid running Kafka, Zookeeper, or Confluent Schema registry for tests, and RedPanda schema registry doesn't support JSON.

Aiven-Open / karapace

Error and connection reset by peer when trying to run against RedPanda #785