140 lines
3.8 KiB
Markdown
140 lines
3.8 KiB
Markdown
---
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title: Use Port Forwarding to Access Applications in a Cluster
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---
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{% capture overview %}
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This page shows how to use `kubectl port-forward` to connect to a Redis
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server running in a Kubernetes cluster. This type of connection can be useful
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for database debugging.
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{% endcapture %}
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{% capture prerequisites %}
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* {% include task-tutorial-prereqs.md %}
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* Install [redis-cli](http://redis.io/topics/rediscli).
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{% endcapture %}
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{% capture steps %}
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## Creating Redis deployment and service
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1. Create a Redis deployment:
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kubectl create -f https://k8s.io/docs/tutorials/stateless-application/guestbook/redis-master-deployment.yaml
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The output of a successful command verifies that the deployment was created:
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deployment "redis-master" created
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When the pod is ready, you can get:
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kubectl get pods
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NAME READY STATUS RESTARTS AGE
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redis-master-765d459796-258hz 1/1 Running 0 50s
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kubectl get deployment
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NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
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redis-master 1 1 1 1 55s
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kubectl get rs
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NAME DESIRED CURRENT READY AGE
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redis-master-765d459796 1 1 1 1m
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2. Create a Redis service:
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kubectl create -f https://k8s.io/docs/tutorials/stateless-application/guestbook/redis-master-service.yaml
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The output of a successful command verifies that the service was created:
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service "redis-master" created
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Check the service created:
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kubectl get svc | grep redis
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NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
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redis-master ClusterIP 10.0.0.213 <none> 6379/TCP 27s
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3. Verify that the Redis server is running in the pod and listening on port 6379:
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{% raw %}
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kubectl get pods redis-master-765d459796-258hz --template='{{(index (index .spec.containers 0).ports 0).containerPort}}{{"\n"}}'
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{% endraw %}
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The output displays the port:
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6379
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## Forward a local port to a port on the pod
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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.
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kubectl port-forward redis-master-765d459796-258hz 6379:6379
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which is the same as
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kubectl port-forward pods/redis-master-765d459796-258hz 6379:6379
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or
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kubectl port-forward deployment/redis-master 6379:6379
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or
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kubectl port-forward rs/redis-master 6379:6379
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or
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kubectl port-forward svc/redis-master 6379:6379
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Any of the above commands works. The output is similar to this:
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I0710 14:43:38.274550 3655 portforward.go:225] Forwarding from 127.0.0.1:6379 -> 6379
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I0710 14:43:38.274797 3655 portforward.go:225] Forwarding from [::1]:6379 -> 6379
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2. Start the Redis command line interface:
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redis-cli
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3. At the Redis command line prompt, enter the `ping` command:
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127.0.0.1:6379>ping
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A successful ping request returns PONG.
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{% endcapture %}
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{% capture discussion %}
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## Discussion
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Connections made to local port 6379 are forwarded to port 6379 of the pod that
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is running the Redis server. With this connection in place you can use your
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local workstation to debug the database that is running in the pod.
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**Warning**: Due to known limitations, port forward today only works for TCP protocol.
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The support to UDP protocol is being tracked in
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[issue 47862](https://github.com/kubernetes/kubernetes/issues/47862).
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{: .warning}
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{% endcapture %}
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{% capture whatsnext %}
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Learn more about [kubectl port-forward](/docs/user-guide/kubectl/{{page.version}}/#port-forward).
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{% endcapture %}
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{% include templates/task.md %}
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