website/content/en/docs/tasks/access-application-cluster/port-forward-access-application-cluster.md

title	content_template	weight
Use Port Forwarding to Access Applications in a Cluster	templates/task	40

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This page shows how to use kubectl port-forward to connect to a Redis server running in a Kubernetes cluster. This type of connection can be useful for database debugging.

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• {{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}

• Install redis-cli.

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Creating Redis deployment and service

1. Create a Redis deployment:

   kubectl create -f https://k8s.io/docs/tutorials/stateless-application/guestbook/redis-master-deployment.yaml
   

   The output of a successful command verifies that the deployment was created:

    deployment "redis-master" created
   

   When the pod is ready, you can get:

   kubectl get pods
   
    NAME                            READY     STATUS    RESTARTS   AGE
    redis-master-765d459796-258hz   1/1       Running   0          50s
   
   kubectl get deployment
   
    NAME         DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
    redis-master 1         1         1            1           55s
   
   kubectl get rs
   
    NAME                      DESIRED   CURRENT   READY     AGE
    redis-master-765d459796   1         1         1         1m
   

2. Create a Redis service:

   kubectl create -f https://k8s.io/docs/tutorials/stateless-application/guestbook/redis-master-service.yaml
   

   The output of a successful command verifies that the service was created:

    service "redis-master" created
   

   Check the service created:

   kubectl get svc | grep redis
   
    NAME           TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)    AGE
    redis-master   ClusterIP   10.0.0.213   <none>        6379/TCP   27s
   

3. Verify that the Redis server is running in the pod and listening on port 6379:

   kubectl get pods redis-master-765d459796-258hz --template='{{(index (index .spec.containers 0).ports 0).containerPort}}{{"\n"}}'
   

   The output displays the port:

    6379
   

Forward a local port to a port on the pod

1. kubectl port-forward allows using resource name, such as a service name, to select a matching pod to port forward to since Kubernetes v1.10.

   kubectl port-forward redis-master-765d459796-258hz 6379:6379 
   

   which is the same as

   kubectl port-forward pods/redis-master-765d459796-258hz 6379:6379
   

   or

   kubectl port-forward deployment/redis-master 6379:6379 
   

   or

   kubectl port-forward rs/redis-master 6379:6379 
   

   or

   kubectl port-forward svc/redis-master 6379:6379
   

   Any of the above commands works. The output is similar to this:

   I0710 14:43:38.274550    3655 portforward.go:225] Forwarding from 127.0.0.1:6379 -> 6379
   I0710 14:43:38.274797    3655 portforward.go:225] Forwarding from [::1]:6379 -> 6379
   

2. Start the Redis command line interface:

   redis-cli
   

3. At the Redis command line prompt, enter the ping command:

   127.0.0.1:6379>ping
   

   A successful ping request returns PONG.

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Discussion

Connections made to local port 6379 are forwarded to port 6379 of the pod that is running the Redis server. With this connection in place you can use your local workstation to debug the database that is running in the pod.

{{< warning >}} Warning: Due to known limitations, port forward today only works for TCP protocol. The support to UDP protocol is being tracked in issue 47862. {{< /warning >}}

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{{% capture whatsnext %}} Learn more about kubectl port-forward. {{% /capture %}}