VPN2

This repository contains components to establish network connectivity for Shoot clusters.

What's inside

VPN Server - a component that configures and runs OpenVPN in server mode. It serves an endpoint for incoming connections and allows contacting any IP address within the networks of a Shoot cluster (which are usually private).

VPN Client- a component that configures and runs OpenVPN in client mode. It establishes connectivity from a Shoot cluster to the endpoint in the Seed cluster allowing contacting any IP address within its network and routes the packets back to the caller.

Main features:

• The VPN supports all combinations of IP families:
  • IPv4 on both sides, i.e. control plane (seed) and shoot
  • IPv4/IPv6 dual stack on control plane (seed) and any IP families on shoot
  • IPv6 on both control plane (seed) and shoot
• It always uses an IPv6 transfer network for the VPN tunnel.
• It supports two modes
  • the default mode is one VPN server on the seed side and one VPN client on the shoot side
  • in HA mode, the VPN connectivity is realized using two separate VPN servers on the control plane side and multiple VPN clients both on control plane and shoot sides combining the two VPN tunnels into a single connection using a bonding device.
• It is written in Go

Please see Reversed VPN Tunnel Setup and Configuration for a detailed discussion of the architecture.

Local test environment

• Set up a local Gardener environment following Deploying Gardener Locally

  Essential step:

  make kind-up gardener-up

• Follow Creating a Shoot Cluster to create a shoot cluster

  Essential step:

  kubectl apply -f example/provider-local/shoot.yaml

• If you want to test the VPN in HA mode, annotate the shoot with

  kubectl -n garden-local annotate shoot local alpha.control-plane.shoot.gardener.cloud/high-availability-vpn=true

• build the docker images and push them to the local Gardener registry with

  VPN client image

  make vpn-client-to-gardener-local

  or to build a debug image containing command line tools like ls, tcpdump and other net-tools use make vpn-client-to-gardener-local DEBUG=true

  Note: Remember the image name reported at the end similar to

  VPN client image: localhost:5001/europe-docker_pkg_dev_gardener-project_public_gardener_vpn-client:0.26.0-dev

  VPN server image

  make vpn-server-to-gardener-local

  or to build a debug image containing command line tools like ls, tcpdump and other net-tools use make vpn-server-to-gardener-local DEBUG=true

  Note: Remember the image name reported at the end similar to

  VPN server image: localhost:5001/europe-docker_pkg_dev_gardener-project_public_gardener_vpn-server:0.26.0-dev

• adjust the image vector file imagevector/images.yaml in Gardener to image repositories and tags provided by the last step

  ...
  - name: vpn-server
  sourceRepository: github.com/gardener/vpn2
  repository: localhost:5001/europe-docker_pkg_dev_gardener-project_public_gardener_vpn-server
  tag: 0.26.0-dev
  ...
  - name: vpn-client
  sourceRepository: github.com/gardener/vpn2
  repository: localhost:5001/europe-docker_pkg_dev_gardener-project_public_gardener_vpn-client
  tag: 0.26.0-dev
  ...
  

  and rerun make gardener-up

• if you rebuild these images you may to have to ensure that the new images are loaded are pulled by the deployments

  • for the vpn-seed-server deployment in the control plane, execute

    kubectl -n shoot--local--local patch deploy vpn-seed-server --patch '{"spec":{"template":{"spec":{"containers":[{"name":"vpn-seed-server","imagePullPolicy":"Always"}]}}}}' 

  • for the shoot client deployment in the shoot, execute

    # first disable managed resource updates in the control plane
    kubectl -n shoot--local--local annotate managedresource shoot-core-vpn-shoot resources.gardener.cloud/ignore=true
    # then target the shoot cluster
    kubectl --kubeconfig admin-kubeconf.yaml -n kube-system patch deploy vpn-shoot --patch '{"spec":{"template":{"spec":{"initContainers":[{"name":"vpn-shoot-init","imagePullPolicy":"Always"}],"containers":[{"name":"vpn-shoot","imagePullPolicy":"Always"}]}}}}' 

  • for the HA deployments run

    kubectl -n shoot--local--local patch deploy kube-apiserver --patch '{"spec":{"template":{"spec":{"initContainers":[{"name":"vpn-client-init","imagePullPolicy":"Always"}]},"containers":[{"name":"vpn-client-0","imagePullPolicy":"Always"}, {"name":"vpn-client-1","imagePullPolicy":"Always"}, {"name":"vpn-path-controller","imagePullPolicy":"Always"}]}}}' 
    kubectl -n shoot--local--local patch sts vpn-seed-server --patch '{"spec":{"template":{"spec":{"containers":[{"name":"vpn-seed-server","imagePullPolicy":"Always"},{"name":"openvpn-exporter","imagePullPolicy":"Always"}]}}}}' 

    and

    # first disable managed resource updates in the control plane
    kubectl -n shoot--local--local annotate managedresource shoot-core-vpn-shoot resources.gardener.cloud/ignore=true
    # then target the shoot cluster
    kubectl --kubeconfig admin-kubeconf.yaml -n kube-system patch sts vpn-shoot --patch '{"spec":{"template":{"spec":{"initContainers":[{"name":"vpn-shoot-init","imagePullPolicy":"Always"}]}}}}' 

Accessing shoot VPN container logs if VPN is down

In case the VPN inside the shoot is not able to connect, it's not possible to stream logs from the Kubernetes API. To get the logs, you can query the machine of the cluster directly for the logs. To do so, use the following command:

MACHINE_POD=$(kubectl get machines -n shoot--local--local -l name=shoot--local--local-local -o jsonpath='{.items[0].metadata.name}')
kubectl exec -n shoot--local--local pod/machine-$MACHINE_POD -ti -- bash -c 'tail -f /var/log/pods/kube-system_vpn-shoot-*/vpn-shoot-*/0.log'

Troubleshoot

HA Setup

vpn-client-init container is crashing

failed to create bond0 link device: operation not supported

Check if you're kernel supports bond devices. You can check on nodes running docker with the following command:
docker run -it --rm --privileged --pid=host ubuntu nsenter -t 1 -m -u -n -i sh -c 'cat /proc/config.gz | gunzip | grep CONFIG_BONDING'

CONFIGURE_BONDING must be set to either "m" or "y".

For more information, see https://www.kernelconfig.io/config_bonding?q=&kernelversion=6.1.90&arch=x86