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Use Port Forwarding to Access Applications in a Cluster

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.

• Before you begin
• Creating a pod to run a Redis server
• Forward a local port to a port on the pod
• Discussion
• What’s next

Before you begin

• You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using Minikube, or you can use one of these Kubernetes playgrounds:

• Katacoda
• Play with Kubernetes

To check the version, enter kubectl version.

• Install redis-cli.

Creating a pod to run a Redis server

1. Create a pod:

   kubectl create -f https://k8s.io/docs/tasks/access-application-cluster/redis-master.yaml
   

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

    pod "redis-master" created
   

2. Check to see whether the pod is running and ready:

   kubectl get pods
   

   When the pod is ready, the output displays a STATUS of Running:

    NAME           READY     STATUS    RESTARTS   AGE
    redis-master   2/2       Running   0          41s
   

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

   kubectl get pods redis-master --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. Forward port 6379 on the local workstation to port 6379 of redis-master pod:

   kubectl port-forward redis-master 6379:6379
   

   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.

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: Due to known limitations, port forward today only works for TCP protocol. The support to UDP protocol is being tracked in issue 47862.

What’s next

Learn more about kubectl port-forward.