mc-router

Flags:
  --help                     Show context-sensitive help (also try --help-long
                             and --help-man).
  --port=25565               The port bound to listen for Minecraft client
                             connections
  --api-binding=API-BINDING  The host:port bound for servicing API requests
  --mapping=MAPPING ...      Mapping of external hostname to internal server
                             host:port

REST API

GET /routes Retrieves the currently configured routes
POST /routes Registers a route given a JSON body structured like:

{
  "serverAddress": "CLIENT REQUESTED SERVER ADDRESS",
  "backend": "HOST:PORT"
}

POST /defaultRoute Registers a default route to the given backend. JSON body is structured as:

{
  "backend": "HOST:PORT"
}

DELETE /routes/{serverAddress} Deletes an existing route for the given serverAddress

Using kubernetes service auto-discovery

When running mc-router as a kubernetes pod and you pass the --in-kube-cluster command-line argument, then it will automatically watch for any services annotated with

mc-router.itzg.me/externalServerName : The value of the annotation will be registered as the external hostname Minecraft clients would used to connect to the routed service. The service's clusterIP and target port are used as the routed backend.
mc-router.itzg.me/defaultServer : The service's clusterIP and target port are used as the default if no other externalServiceName annotations applies.

For example, start mc-router's container spec with

image: itzg/mc-router
name: mc-router
args: ["--in-kube-cluster"]

and configure the backend minecraft server's service with the annotation:

apiVersion: v1
kind: Service
metadata:
  name: mc-forge
  annotations:
    "mc-router.itzg.me/externalServerName": "external.host.name"

Example kubernetes deployment

This example deployment

Declares an mc-router service that exposes a node port 25565
Declares a service account with access to watch and list services
Declares --in-kube-cluster in the mc-router container arguments
Two "backend" Minecraft servers are declared each with an "mc-router.itzg.me/externalServerName" annotation that declares their external server name

kubectl apply -f https://raw.githubusercontent.com/itzg/mc-router/master/docs/k8s-example-auto.yaml

Notes

This deployment assumes two persistent volume claims: mc-stable and mc-snapshot
I extended the allowed node port range by adding --service-node-port-range=25000-32767 to /etc/kubernetes/manifests/kube-apiserver.yaml