I have the following configuration for my kafka and zookeeper in my minikube:
apiVersion: v1
kind: Service
metadata:
name: kafka-service
namespace: kafka
spec:
selector:
app: kafka
ports:
- protocol: TCP
port: 9092
name: kafka-port
- protocol: TCP
port: 9094
name: kafka-port-out
- protocol: TCP
port: 2181
name: kafka-zk
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: kafka-deployment
namespace: kafka
spec:
replicas: 1
selector:
matchLabels:
app: kafka
k8s-app: kube-dns
template:
metadata:
labels:
app: kafka
k8s-app: kube-dns
spec:
containers:
- name: kafka-container
image: bitnami/kafka:latest
env:
- name: 'ALLOW_PLAINTEXT_LISTENER'
value: 'yes'
- name: 'KAFKA_CFG_ZOOKEEPER_CONNECT'
value: 'zookeeper-service:2181'
- name: 'KAFKA_CFG_LISTENERS'
value: 'PLAINTEXT://:9092'
- name: 'KAFKA_CFG_ADVERTISED_LISTENERS' # if I comment this and the next line it works only locally
value: 'PLAINTEXT://kafka-service.kafka:9092'
ports:
- containerPort: 9092
name: kafka-port
- containerPort: 9094
name: kafka-port-out
- containerPort: 5555
name: kafka-port-jmx
- containerPort: 2181
name: kafka-zk
That is the configuration for my zookeeper:
apiVersion: v1
kind: Service
metadata:
name: zookeeper-service
namespace: kafka
spec:
selector:
app: zookeeper
ports:
- protocol: TCP
port: 2181
name: zookeeper-port
- protocol: TCP
port: 2888
name: zookeeper-peer
- protocol: TCP
port: 3888
name: leader-election
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: zookeeper-deployment
namespace: kafka
spec:
replicas: 1
selector:
matchLabels:
app: zookeeper
k8s-app: kube-dns
template:
metadata:
labels:
app: zookeeper
k8s-app: kube-dns
spec:
containers:
- name: zookeeper-container
image: bitnami/zookeeper:latest
env:
- name: 'ALLOW_ANONYMOUS_LOGIN'
value: 'yes'
- name: 'ZOOKEEPER_ID'
value: '1'
ports:
- containerPort: 2181
name: zookeeper-port
- containerPort: 2888
name: zookeeper-peer
- containerPort: 3888
name: leader-election
And I have another deployment:
apiVersion: apps/v1
kind: Deployment
metadata:
name: kafkacat-deployment
# namespace: debug # I was using it from another namespace, but it was not working so I've tried to use the same
namespace: kafka
spec:
replicas: 1
selector:
matchLabels:
app: kafkacat
k8s-app: kube-dns
template:
metadata:
labels:
app: kafkacat
k8s-app: kube-dns
spec:
containers:
- name: kafkacat-container
image: edenhill/kafkacat:1.5.0
Then I try to telnet it, and it works.
telnet kafka-service.kafka 9092
Trying 10.101.87.127...
Connected to kafka-service.kafka.svc.cluster.local.
Escape character is '^]'.
Here is the nslookup
nslookup kafka-service.kafka
Server: 10.96.0.10
Address: 10.96.0.10#53
Name: kafka-service.kafka.svc.cluster.local
Address: 10.101.87.127
But when I try to reach it that is what I get:
kafkacat -b kafka-service.kafka:9092 -L
% ERROR: Failed to acquire metadata: Local: Timed out
So my guess it that the problem is in the Kafka configuration:
If I comment the env var KAFKA_CFG_ADVERTISED_LISTENERS it it works like that:
# kafkacat -b kafka-service.kafka:9092 -L
Metadata for all topics (from broker -1: kafka-service.kafka:9092/bootstrap):
1 brokers:
broker 1001 at kafka-deployment-858c5c7f98-tt7sr:9092
2 topics:
topic "my_topic" with 1 partitions:
partition 0, leader 1001, replicas: 1001, isrs: 1001
topic "__consumer_offsets" with 50 partitions:
partition 0, leader 1001, replicas: 1001, isrs: 1001
If I try to produce a message:
kafkacat -b kafka-service.kafka:9092 -P -t my_topic
oi
% ERROR: Local: Host resolution failure: kafka-deployment-858c5c7f98-w2dm5:9092/1001: Failed to resolve 'kafka-deployment-858c5c7f98-w2dm5:9092': Temporary failure in name resolution (after 15382734ms in state INIT)
Then if I try to consume:
kafkacat -b kafka-service.kafka:9092 -C -t my_topic
% ERROR: Local: Host resolution failure: kafka-deployment-858c5c7f98-w2dm5:9092/1001: Failed to resolve 'kafka-deployment-858c5c7f98-w2dm5:9092': Temporary failure in name resolution (after 15406287ms in state INIT)
I have tried to configure the KAFKA_CFG_ADVERTISED_LISTENERS=PLAINTEXT://kafka-service.kafka.svc.cluster.local:9092 but I still get timeout when I try to get the information with kafkacat.
That is why the advertised listener is the hostname which is not reachable from the local machine. What can I do to fix the Kafka configuration in the cluster?
I applied the exact same manifest as you provided except for adding a follow tail into /dev/null on kafka-deployment pod and was able to produce and consume topics.
I am running a k3s cluster in k3d:
└[~]> kubectl get nodes
NAME STATUS ROLES AGE VERSION
k3d-dev-server Ready master 31m v1.17.3+k3s1
k3d-dev-worker-1 Ready <none> 31m v1.17.3+k3s1
kafka-deployment manifest:
apiVersion: apps/v1
kind: Deployment
metadata:
name: kafkacat-deployment
# namespace: debug # I was using it from another namespace, but it was not working so I've tried to use the same
namespace: kafka
spec:
replicas: 1
selector:
matchLabels:
app: kafkacat
k8s-app: kube-dns
template:
metadata:
labels:
app: kafkacat
k8s-app: kube-dns
spec:
containers:
- name: kafkacat-container
image: edenhill/kafkacat:1.5.0
resources: {}
command:
- sh
- -c
- "exec tail -f /dev/null"
Terminal logs from kafka-deployment pod in Kafka namespace:
/ # kafkacat -b kafka-service.kafka:9092 -L
Metadata for all topics (from broker 1001: kafka-service.kafka:9092/1001):
1 brokers:
broker 1001 at kafka-service.kafka:9092 (controller)
0 topics:
/ # kafkacat -b kafka-service.kafka:9092 -P -t my_topic
hi from kafkacat
/ # kafkacat -b kafka-service.kafka:9092 -C -t my_topic
hi from kafkacat
% Reached end of topic my_topic [0] at offset 1
/ # kafkacat -b kafka-service:9092 -L
Metadata for all topics (from broker -1: kafka-service:9092/bootstrap):
1 brokers:
broker 1001 at kafka-service.kafka:9092 (controller)
1 topics:
topic "my_topic" with 1 partitions:
partition 0, leader 1001, replicas: 1001, isrs: 1001
/ # kafkacat -b kafka-service:9092 -P -t my_topic
hi from kafka2
/ # kafkacat -b kafka-service:9092 -C -t my_topic
hi from kafkacat
hi from kafka2
% Reached end of topic my_topic [0] at offset 2
Terminal logs of kafka-deployment from debug namespace:
└[~]> kubectl exec -it kafkacat-deployment-76f9c9db6d-8fth4 -n debug -- ash
/ # kafkacat -b kafka-service.kafka:9092 -L
Metadata for all topics (from broker 1001: kafka-service.kafka:9092/1001):
1 brokers:
broker 1001 at kafka-service.kafka:9092 (controller)
1 topics:
topic "my_topic" with 1 partitions:
partition 0, leader 1001, replicas: 1001, isrs: 1001
/ # kafkacat -b kafka-service.kafka:9092 -P -t my_topic
hi from debug namespace
/ # kafkacat -b kafka-service.kafka:9092 -C -t my_topic
hi from kafkacat
hi from kafka2
hi from debug namespace
% Reached end of topic my_topic [0] at offset 3
I got it to work in minikube as well, after applying a workaround for a bug in minikube:
minikube ssh
sudo ip link set docker0 promisc on
Deleted the running kafka-deployment pod and it worked from both namespaces:
(⎈ |minikube:default)➜ ~ kubectl delete pod -n kafka kafka-deployment-5c4f64599f-kn9xt
pod "kafka-deployment-5c4f64599f-kn9xt" deleted
(⎈ |minikube:default)➜ ~ kubectl exec -n kafka -it kafkacat-deployment-b595d9ccd-4bht7 -- ash
/ # kafkacat -b kafka-service.kafka:9092 -L
Metadata for all topics (from broker 1003: kafka-service.kafka:9092/1003):
1 brokers:
broker 1003 at kafka-service.kafka:9092 (controller)
0 topics:
/ #
(⎈ |minikube:default)➜ ~ kubectl exec -n debug -it kafkacat-deployment-b595d9ccd-pgzv6 -- ash
/ # kafkacat -b kafka-service.kafka:9092 -L
Metadata for all topics (from broker 1003: kafka-service.kafka:9092/1003):
1 brokers:
broker 1003 at kafka-service.kafka:9092 (controller)
0 topics:
/ #