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pod-gateway

This container includes scripts used to route trafic from pods through another gateway pod. Typically the gateway pod then runs a openvpn client to forward the traffic.

This container is injected by the gateway-admision-controller so that existing K8S PODs can be extended to route their trafic through a VPN. Check the README to learn how to use it.

The connection between the pods is done via a vxlan. The gatway provides a DHCP server to let client pods to get automatically an IP.

Ougoing traffic is masqueraded (SNAT). It is also possible to define port forwardind so ports of client pods can be reached from the outside.

The .github folder will get PRs from this template so you can apply the latest workflows.

Design

Client PODs are connected through a tunnel to the gateway POD and route default traffic and DNS queries through it. The tunnel is implemented as VXLAN overlay.

This container provides the required init/sidecar containers for clients and gateway PODs:

  • client PODs connecting through gateway POD:
    • client_init.sh: starts the VXLAN tunnel and change the default gateway in the POD. It can get its IP via DHCP or use an static IP within the VXLAN (needed for port) forwarding.
    • client_sidecar.sh: periodically checks connection to the gateway is still working. Reset the vxlan if this is not the case. This happens, for example, when the gateway POD is restarted and it gets a new IP from K8S.
  • gateway POD:
    • gateway_init.sh: creates the VXLAN tunnel and set traffic forwading rules. Optionally, if a VPN is used in the gateway, blocks non VPN outbound traffic.
    • gateway_sidecar.sh: deploys a DHCP and DNS server

Settings are expected in the /config folder - see examples under config:

  • config/settings.sh: variables used by all helper scripts
  • config/nat.conf: static IP and nat rules for PODs exposing ports through the gateway (and optional VPN) POD Default settings might be overwritten by attachin a container volume with the new values to the helper pods.

Prereqs

You need to create the following secrets (not needed within the k8s-at-home org - there we use org-wide secrets):

  • WORKFLOW_REPO_SYNC_TOKEN # Needed to do PRs that update the workflows
  • GHCR_USERNAME # Needed to upload container to the Github Container Registry
  • GHCR_TOKEN # Needed to upload container to the Github Container Registry

How to build

  1. Build the container 
    make

Testing requires multiple containers - see the gateway-admision-controller and check the Makefile for other build targets.