Expose Load-balancer port through uPNP

[thebsdbox]

This is technically possible to expose the port mapping to a commercial router so we could:

• Create VIP
• Create Load-balancer
• Expose VIP:Port to router:port through uPNP

kubectl expose deployment nginx-deployment --port=18080 --type=LoadBalancer --name=nginx-loadbalancer

The --port=xxx will need to be considered for the uPNP endpoint (router)

Errors will be hard to handle as it's not something that Kubernetes load-balancers are designed to handle, errors would exist the kube-vip pod in the namespace the load-balancer is created in. This is where an end-user would find that the exposed port hasn't made it to the router (such as having an already existing port-mapping created).

cc / @displague

[thebsdbox]

package main

import "fmt"
import "github.com/yanzay/upnp"

func main() {

upnpMan := new(upnp.Upnp)
err := upnpMan.SearchGateway()
if err != nil {
        fmt.Println(err.Error())
} else {
        fmt.Println("local ip address: ", upnpMan.LocalHost)
        fmt.Println("gateway ip address: ", upnpMan.Gateway.Host)
}

err = upnpMan.ExternalIPAddr()
if err != nil {
        fmt.Println(err.Error())
} else {
        fmt.Println("internet ip address: ", upnpMan.GatewayOutsideIP)
}

>  cat main.go                                                      upnp-master
package main

import "fmt"
import "github.com/yanzay/upnp"

func main() {

upnpMan := new(upnp.Upnp)
err := upnpMan.SearchGateway()
if err != nil {
	fmt.Println(err.Error())
} else {
	fmt.Println("local ip address: ", upnpMan.LocalHost)
	fmt.Println("gateway ip address: ", upnpMan.Gateway.Host)
}

err = upnpMan.ExternalIPAddr()
if err != nil {
	fmt.Println(err.Error())
} else {
	fmt.Println("internet ip address: ", upnpMan.GatewayOutsideIP)
}

mapping := new(upnp.Upnp)
if err := mapping.AddPortMapping(22, 55789, "TCP"); err == nil {
	fmt.Println("success !")
	// remove port mapping in gatway
//	mapping.Reclaim()
} else {
	fmt.Println("fail !")
}

}

^ earlier testing (needs to put it somewhere)

[displague]

I'm adding relevant keywords so this can be better found in Google searches:
https://tools.ietf.org/html/rfc6970
Universal Plug and Play (UPnP), Internet Gateway Device - Port Control Protocol Interworking Function, (IGD-PCP IWF)

[displague]

I ran this PoC code (with the router port 22 and a 100s port removal). This is awesome!

[displague]

A uPNP CCM could query the network (SSDP) to find out if a node is no longer available (to remove it from the cluster), https://www.electricmonk.nl/log/2016/07/05/exploring-upnp-with-python/

[thebsdbox]

Attempted to implement this only to be hit with a brick wall ->
VIP 192.168.0.201
Host 192.168.0.45

I can't advertise the VIP to the router, only the address of the host itself

[thebsdbox]

Merged as of #96