Understand port forwarding
You can use the OpenShift CLI (oc) to forward one or more local ports to a pod. This allows you to listen on a given or random port locally, and have data forwarded to and from given ports in the pod.
You can use a command similar to the following to forward one or more local ports to a pod.
$ oc port-forward <pod> [<local_port>:]<remote_port> [...[<local_port_n>:]<remote_port_n>]The OpenShift CLI (oc) listens on each local port specified by the user, forwarding using the protocol described below.
You can specify ports by using the following formats:
5000
|
The client listens on port 5000 locally and forwards to 5000 in the pod. |
6000:5000
|
The client listens on port 6000 locally and forwards to 5000 in the pod. |
:5000 or 0:5000
|
The client selects a free local port and forwards to 5000 in the pod. |
Red Hat OpenShift Container Platform handles port-forward requests from clients. Upon receiving a request, Red Hat OpenShift Container Platform upgrades the response and waits for the client to create port-forwarding streams. When Red Hat OpenShift Container Platform receives a new stream, it copies data between the stream and the pod’s port.
Architecturally, there are options for forwarding to a pod’s port. The supported Red Hat OpenShift Container Platform implementation invokes nsenter directly on the node host
to enter the pod’s network namespace, then invokes socat to copy data between the stream and the pod’s port. However, a custom implementation could
include running a helper pod that then runs nsenter and socat, so that those binaries are not required to be installed on the host.