Broker may not be available error Kafka schema registry
You've configured Schema Registry to look for the Kafka broker at kafka:9092, but you've also configured the Kafka broker to advertise its address as localhost:9092.
I'm not familiar with Kubernetes specifically, but this article describes how to handle networking config in principle when using containers, IaaS, etc.
I was getting the same kind of error and I followed cricket_007's answer and it got resolved.
Just change KAFKA_ADVERTISED_LISTENERS value from PLAINTEXT://localhost:9092 to PLAINTEXT://schema-registry-service:9092