How can I fix Kafka Bitnami (KRaft) restart issues on Kubernetes due to missing controller port exposure?

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I'm encountering repeated restarts when deploying Kafka Bitnami in KRaft mode on Kubernetes. The deployment appears to be misconfigured, as Kafka logs show an error: channel manager timed out before sending the request. Interestingly, the same configuration works fine with Docker Compose.

Below is the Kubernetes deployment file being used:

YAML
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: kafka
  name: kafka
spec:
  replicas: 1
  selector:
    matchLabels:
      app: kafka
  template:
    metadata:
      labels:
        app: kafka
    spec:
      containers:
        - env:
            - name: ALLOW_PLAINTEXT_LISTENER
              value: "yes"
            - name: KAFKA_BROKER_ID
              value: "1"
            - name: KAFKA_CFG_ADVERTISED_LISTENERS
              value: PLAINTEXT://kafka:9092
            - name: KAFKA_CFG_CONTROLLER_LISTENER_NAMES
              value: CONTROLLER
            - name: KAFKA_CFG_CONTROLLER_QUORUM_VOTERS
              value: 1@kafka:9093
            - name: KAFKA_CFG_LISTENERS
              value: PLAINTEXT://:9092,CONTROLLER://:9093
            - name: KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP
              value: CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT
            - name: KAFKA_CFG_NODE_ID
              value: "1"
            - name: KAFKA_CFG_PROCESS_ROLES
              value: broker,controller
            - name: KAFKA_ENABLE_KRAFT
              value: "yes"
            - name: KAFKA_KRAFT_CLUSTER_ID
              value: MkU3OEVBNTcwNTJENDM2Qk
          image: bitnami/kafka:3.9.0
          name: kafka
          ports:
            - containerPort: 9092
              protocol: TCP
      restartPolicy: Always

---

apiVersion: v1
kind: Service
metadata:
  labels:
    app: kafka
  name: kafka
spec:
  ports:
    - name: "9092"
      port: 9092
      targetPort: 9092
  selector:
    app: kafka

The logs from Kubernetes are as follows:

BASH
[2025-01-25 08:04:58,857] INFO [broker-1-to-controller-heartbeat-channel-manager]: Recorded new KRaft controller, from now on will use node kafka:9093 (id: 1 rack: null) (kafka.server.NodeToControllerRequestThread)
[2025-01-25 08:04:58,857] INFO [BrokerLifecycleManager id=1] Unable to register the broker because the RPC got timed out before it could be sent. (kafka.server.BrokerLifecycleManager)
[2025-01-25 08:04:58,963] INFO [controller-1-to-controller-registration-channel-manager]: Recorded new KRaft controller, from now on will use node kafka:9093 (id: 1 rack: null) (kafka.server.NodeToControllerRequestThread)
[2025-01-25 08:04:58,965] ERROR [ControllerRegistrationManager id=1 incarnation=zHQ1Oie1TRW4qje9o_Pmow] RegistrationResponseHandler: channel manager timed out before sending the request. (kafka.server.ControllerRegistrationManager)
[2025-01-25 08:04:59,066] INFO [ControllerRegistrationManager id=1 incarnation=zHQ1Oie1TRW4qje9o_Pmow] maybeSendControllerRegistration: waiting for the previous RPC to complete. (kafka.server.ControllerRegistrationManager)
[2025-01-25 08:05:03,460] INFO [broker-1-to-controller-heartbeat-channel-manager]: Recorded new KRaft controller, from now on will use node kafka:9093 (id: 1 rack: null) (kafka.server.NodeToControllerRequestThread)
[2025-01-25 08:05:03,460] INFO [BrokerLifecycleManager id=1] Unable to register the broker because the RPC got timed out before it could be sent. (kafka.server.BrokerLifecycleManager)
[2025-01-25 08:05:08,169] INFO [NodeToControllerChannelManager id=1 name=heartbeat] Disconnecting from node 1 due to socket connection setup timeout. The timeout value is 9499 ms. (org.apache.kafka.clients.NetworkClient)
[2025-01-25 08:05:08,172] INFO [broker-1-to-controller-heartbeat-channel-manager]: Recorded new KRaft controller, from now on will use node kafka:9093 (id: 1 rack: null) (kafka.server.NodeToControllerRequestThread)
[2025-01-25 08:05:08,172] INFO [BrokerLifecycleManager id=1] Unable to register the broker because the RPC got timed out before it could be sent. (kafka.server.BrokerLifecycleManager)
[2025-01-25 08:05:08,977] INFO [NodeToControllerChannelManager id=1 name=registration] Disconnecting from node 1 due to socket connection setup timeout. The timeout value is 11048 ms. (org.apache.kafka.clients.NetworkClient)
[2025-01-25 08:05:13,079] INFO [broker-1-to-controller-heartbeat-channel-manager]: Recorded new KRaft controller, from now on will use node kafka:9093 (id: 1 rack: null) (kafka.server.NodeToControllerRequestThread)
[2025-01-25 08:05:13,079] INFO [BrokerLifecycleManager id=1] Unable to register the broker because the RPC got timed out before it could be sent. (kafka.server.BrokerLifecycleManager)

For reference, here is the Docker Compose configuration that works without issues:

YAML
  kafka:
    image: bitnami/kafka:3.9.0
    container_name: kafka
    ports:
      - 9092:9092
    environment:
      - KAFKA_ENABLE_KRAFT=yes
      - KAFKA_CFG_PROCESS_ROLES=broker,controller
      - KAFKA_CFG_CONTROLLER_LISTENER_NAMES=CONTROLLER
      - KAFKA_CFG_LISTENERS=PLAINTEXT://:9092,CONTROLLER://:9093
      - KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP=CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT
      - KAFKA_CFG_ADVERTISED_LISTENERS=PLAINTEXT://kafka:9092
      - KAFKA_BROKER_ID=1
      - KAFKA_CFG_CONTROLLER_QUORUM_VOTERS=1@kafka:9093
      - ALLOW_PLAINTEXT_LISTENER=yes
      - KAFKA_CFG_NODE_ID=1
      - KAFKA_KRAFT_CLUSTER_ID=MkU3OEVBNTcwNTJENDM2Qk
    networks:
      - network

Test setup details:

Windows 11 OS
Docker 27.4.0
Kubernetes (Kind 0.26.0)

Source code is available here:

Github: https://github.com/wisniewskikr/chrisblog-it-java-springboot/blob/main/arichitectures/event-driven/stream/kafka/kraft/springboot3-eventdriven-kafka-bitnami/k8s/kafka-bitnami/infrastructure/kafka.yaml

Any suggestions on how to resolve this issue and why Kubernetes requires a different configuration compared to Docker Compose?

Comments 0

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 1 month ago

Below is one likely explanation and solution based on how networking is handled differently in Docker Compose versus Kubernetes.

The Issue

In your Docker Compose configuration the container’s hostname (set via container_name) and the network setup ensure that both the broker port (9092) and the internal controller port (9093) are available to the container. The Bitnami Kafka image (in KRaft mode) listens on two endpoints:

A public broker listener on port 9092
An internal controller listener on port 9093

Your Kubernetes deployment currently exposes only port 9092 (both in the container ports and in the Service). The advertised listener for the controller is set to use “kafka:9093” (and similarly in quorum voters), but no service (or explicit container port) exists for port 9093. As a result, the broker tries to send RPCs over 9093 but the connection can’t be established, leading to the timeout error (i.e. “channel manager timed out before sending the request”) and continuous restarts.

The Difference in Environments

Docker Compose:
The Docker Compose file uses a container name and a custom network so that even if only one port is published externally, the container’s internal networking makes both 9092 and 9093 available for internal communication.
Kubernetes:
In Kubernetes the container is scheduled in a pod without an implicit hostname alias. Even though the Kafka process might be listening on both ports, exposing only port 9092 in the pod and service means the controller’s port (9093) is not reachable via the DNS name “kafka”. This disrupts internal communications required by KRaft.

How to Fix

Adjust your Kubernetes configuration so that both ports (9092 and 9093) are available. There are two main changes needed:

Expose port 9093 in the Deployment:
Define both container ports so that the Kafka process can receive network traffic on 9093 within the pod.
Expose port 9093 in your Service:
Update the Service definition to include 9093 (with an appropriate name) so that the DNS entry “kafka” resolves to an endpoint that accepts traffic on both ports.

Updated Deployment Example

YAML
apiVersion: apps/v1
kind: Deployment
metadata:
  name: kafka
  labels:
    app: kafka
spec:
  replicas: 1
  selector:
    matchLabels:
      app: kafka
  template:
    metadata:
      labels:
        app: kafka
    spec:
      containers:
        - name: kafka
          image: bitnami/kafka:3.9.0
          env:
            - name: ALLOW_PLAINTEXT_LISTENER
              value: "yes"
            - name: KAFKA_BROKER_ID
              value: "1"
            - name: KAFKA_CFG_ADVERTISED_LISTENERS
              value: PLAINTEXT://kafka:9092
            - name: KAFKA_CFG_CONTROLLER_LISTENER_NAMES
              value: CONTROLLER
            - name: KAFKA_CFG_CONTROLLER_QUORUM_VOTERS
              value: 1@kafka:9093
            - name: KAFKA_CFG_LISTENERS
              value: PLAINTEXT://:9092,CONTROLLER://:9093
            - name: KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP
              value: CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT
            - name: KAFKA_CFG_NODE_ID
              value: "1"
            - name: KAFKA_CFG_PROCESS_ROLES
              value: broker,controller
            - name: KAFKA_ENABLE_KRAFT
              value: "yes"
            - name: KAFKA_KRAFT_CLUSTER_ID
              value: MkU3OEVBNTcwNTJENDM2Qk
          ports:
            - containerPort: 9092
              protocol: TCP
            - containerPort: 9093
              protocol: TCP
      restartPolicy: Always

Updated Service Example

YAML
apiVersion: v1
kind: Service
metadata:
  name: kafka
  labels:
    app: kafka
spec:
  selector:
    app: kafka
  ports:
    - name: plaintext
      port: 9092
      targetPort: 9092
    - name: controller
      port: 9093
      targetPort: 9093

Summary

The Docker Compose version works because the container’s internal network makes both ports reachable, while your Kubernetes setup was missing an explicit configuration for port 9093. By updating both the Deployment and Service to expose port 9093, the KRaft controller communication should work correctly and prevent the timeouts that are causing Kafka to restart.

Make sure the changes suit your environment (DNS resolution, internal networking) and test the updated deployment.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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