Kafka 连接 - 无法连接到本地主机端口 8083：连接被拒绝

Question

I have an application that relies on a kafka service.

With Kafka connect, I'm getting an error when trying to curl localhost:8083 , on the Linux VM that's running the kube.netes pod for Kafka connect.

curl -v localhost:8083 gives:

• Rebuilt URL to: localhost:8083/
• Trying 127.0.0.1...
• connect to 127.0.0.1 port 8083 failed: Connection refused
• Failed to connect to localhost port 8083: Connection refused
• Closing connection 0 curl: (7) Failed to connect to localhost port 8083: Connection refused

kubectl get po -o wide for my kube.netes namespace gives:

When I check open ports using sudo lsof -i -P -n | grep LISTENsudo lsof -i -P -n | grep LISTEN I don't see 8083 listed. The kafka connect pod is running and there's nothing suspicious in the logs for the pod.

There's a kube.netes manifest that I think was probably used to set up the Kafka connect service, these are the relevant parts. I'd really appreciate any advice about how to figure out why I can't curl localhost:8083

apiVersion: apps/v1
kind: Deployment
metadata:
   name: kafka-connect
   namespace: my-namespace
spec:

   ...

   template:
     metadata:
       labels:
         app: connect
     spec:
        containers:
          - name: kafka-connect
            image: confluentinc/cp-kafka-connect:3.0.1
            ports:
              - containerPort: 8083

            env:
              
              - name: CONNECT_REST_PORT
                value: "8083"
              - name: CONNECT_REST_ADVERTISED_HOST_NAME
                value: "kafka-connect"

        volumes:
          - name: connect-plugins
            persistentVolumeClaim:
                claimName: pvc-connect-plugin
          - name: connect-helpers          
            secret:
              secretName: my-kafka-connect-config
---
apiVersion: v1
kind: Service
metadata:
  name: kafka-connect
  namespace: my-namespace
  labels:
    app: connect  
spec:
  ports:
    - port: 8083
  selector:
    app: connect

Answer 1

You can't connect to a service running inside your cluster, from outside your cluster, without a little bit of tinkering.

You have three possible solutions:

1. Use a service with type NodePort or LoadBalancer to make the service reachable outside the cluster.

   See the services and kubectl expose documentation.
   Be aware, depending on your environment, this may expose the service to the inte.net.

2. Access using Proxy Verb: (see here )

   This only works for HTTP/HTTPS. Use this if your service is not secure enough to be exposed to the inte.net.

3. Access from pod running inside your cluster.

   As you have noticed in the comments, you can curl from inside the pod. You can also do this from any other pod running in the same cluster. Pods can communicate with each other without any additional configuration.

---

Why can I not curl 8083 when I ssh onto the VM?

Pods/services are not reachable from outside the cluster, if not exposed using aforementioned methods (point 1 or 2).

Why isn't the port exposed on the host VM that has the pods?

It's not exposed on your VM, it's exposed inside your cluster.

---

I would strongly recommend going through Cluster Networking documentation to learn more.