port-forward

Port Forward is a Kubernetes Controller that forwards external ports to Kubernetes Services of type LoadBalancer which have been assigned private IP addresses. This is useful for clusters using something like MetalLB to expose Services internally that then want to expose some of them externally.

use

Install Port Forward:

kubectl kustomize https://github.com/frantjc/port-forward/config/default?ref=v0.1.6 | kubectl apply -f-

Don't have MetalLB or something else to assign an IP address to the Service? Try adding the argument --override-ip-address=192.168.0.11 to Port Forward.

And give it something to do:

kubectl apply -f - <<EOF
apiVersion: v1
kind: Service
metadata:
  name: sample
  annotations:
    pf.frantj.cc/forward: "yes"
spec:
  type: LoadBalancer
  ports:
    - port: 443
      targetPort: 443
  selector:
    your-label: your-pod
EOF

See sample for full list of supported annotations and their descriptions.

developing

You’ll need a Kubernetes cluster to run against. You can use KIND to get a local cluster for testing. Running against a remote cluster is likely not to work as the UPnP implementations rely on being on the host network of a Node of the cluster.

Port Forward will automatically use the current context in your kubeconfig file (i.e. whatever cluster kubectl cluster-info shows).

Uses the Kubernetes Operator pattern.

Uses a Controller, which provides a reconcile function responsible for continually synchronizing Services of type LoadBalancer to reach and maintain the desired state.

More information can be found via the Kubebuilder Documentation.

Uses SNAT and UPnP to tell a router what to port forward. Written in such a way that more secure implementations can be written for networking devices that support them such as OPNsense which has an API to do such things.