Broker may not be available error Kafka schema registry - kubernetes

Question

I have defined Kafka and Kafka schema registry configuration using Kubernetes deployments and services. I used this link as a reference for the environment variables set up. However, when I try to run Kafka with registry I see that the schema registry pods crashes with an error message in the logs:
[kafka-admin-client-thread | adminclient-1] WARN
org.apache.kafka.clients.NetworkClient - [AdminClient
clientId=adminclient-1] Connection to node -1
(localhost/127.0.0.1:9092) could not be established. Broker may not be
available.
[main] ERROR io.confluent.admin.utils.ClusterStatus - Error while getting broker list.
java.util.concurrent.ExecutionException: org.apache.kafka.common.errors.TimeoutException: Timed out waiting for
a node assignment.
What could be the reason of this error?
apiVersion: v1
kind: Service
metadata:
name: kafka-service
spec:
ports:
- name: client
port: 9092
selector:
app: kafka
server-id: "1"
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: kafka-1
spec:
selector:
matchLabels:
app: kafka
server-id: "1"
replicas: 1
template:
metadata:
labels:
app: kafka
server-id: "1"
spec:
volumes:
- name: kafka-data
emptyDir: {}
containers:
- name: server
image: confluentinc/cp-kafka:5.1.0
env:
- name: KAFKA_ZOOKEEPER_CONNECT
value: zookeeper:2181
- name: KAFKA_ADVERTISED_LISTENERS
value: PLAINTEXT://localhost:9092
- name: KAFKA_BROKER_ID
value: "2"
- name: KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR
value: "1"
ports:
- containerPort: 9092
volumeMounts:
- mountPath: /var/lib/kafka
name: kafka-data
---
apiVersion: v1
kind: Service
metadata:
name: schema-registry-service
spec:
ports:
- name: client
port: 8081
selector:
app: kafka-schema-registry
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: kafka-schema-registry
spec:
replicas: 1
selector:
matchLabels:
app: kafka-schema-registry
template:
metadata:
labels:
app: kafka-schema-registry
spec:
containers:
- name: kafka-schema-registry
image: confluentinc/cp-schema-registry:5.1.0
env:
- name: SCHEMA_REGISTRY_KAFKASTORE_CONNECTION_URL
value: zookeeper:2181
- name: SCHEMA_REGISTRY_HOST_NAME
value: localhost
- name: SCHEMA_REGISTRY_LISTENERS
value: "http://0.0.0.0:8081"
- name: SCHEMA_REGISTRY_KAFKASTORE_BOOTSTRAP_SERVERS
value: PLAINTEXT://localhost:9092
ports:
- containerPort: 8081

Answer 1

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.

Answer 2

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