⚠️ Repo Archive Notice

As of Nov 13, 2020, charts in this repo will no longer be updated. For more information, see the Helm Charts Deprecation and Archive Notice, and Update.

Helm chart for OpenVPN

This chart will install an OpenVPN server inside a kubernetes cluster. New certificates are generated on install, and a script is provided to generate client keys as needed. The chart will automatically configure dns to use kube-dns and route all network traffic to kubernetes pods and services through the vpn. By connecting to this vpn a host is effectively inside a cluster's network.

DEPRECATION NOTICE

This chart is deprecated and no longer supported.

Uses

The primary purpose of this chart was to make it easy to access kubernetes services during development. It could also be used for any service that only needs to be accessed through a vpn or as a standard vpn.

Usage

helm repo add stable http://storage.googleapis.com/kubernetes-charts
helm install stable/openvpn

Wait for the external load balancer IP to become available. Check service status via: kubectl get svc

Please be aware that certificate generation is variable and may take some time (minutes). Check pod status, replacing $HELM_RELEASE with the name of your release, via:

POD_NAME=$(kubectl get pods -l "app=openvpn,release=$HELM_RELEASE" -o jsonpath='{.items[0].metadata.name}') \
&& kubectl logs "$POD_NAME" --follow

When all components of the openvpn chart have started use the following script to generate a client key:

#!/bin/bash

if [ $# -ne 3 ]
then
  echo "Usage: $0 <CLIENT_KEY_NAME> <NAMESPACE> <HELM_RELEASE>"
  exit
fi

KEY_NAME=$1
NAMESPACE=$2
HELM_RELEASE=$3
POD_NAME=$(kubectl get pods -n "$NAMESPACE" -l "app=openvpn,release=$HELM_RELEASE" -o jsonpath='{.items[0].metadata.name}')
SERVICE_NAME=$(kubectl get svc -n "$NAMESPACE" -l "app=openvpn,release=$HELM_RELEASE" -o jsonpath='{.items[0].metadata.name}')
SERVICE_IP=$(kubectl get svc -n "$NAMESPACE" "$SERVICE_NAME" -o go-template='{{range $k, $v := (index .status.loadBalancer.ingress 0)}}{{$v}}{{end}}')
kubectl -n "$NAMESPACE" exec -it "$POD_NAME" /etc/openvpn/setup/newClientCert.sh "$KEY_NAME" "$SERVICE_IP"
kubectl -n "$NAMESPACE" exec -it "$POD_NAME" cat "/etc/openvpn/certs/pki/$KEY_NAME.ovpn" > "$KEY_NAME.ovpn"

In order to revoke certificates in later steps:

#!/bin/bash

if [ $# -ne 3 ]
then
  echo "Usage: $0 <CLIENT_KEY_NAME> <NAMESPACE> <HELM_RELEASE>"
  exit
fi

KEY_NAME=$1
NAMESPACE=$2
HELM_RELEASE=$3
POD_NAME=$(kubectl get pods -n "$NAMESPACE" -l "app=openvpn,release=$HELM_RELEASE" -o jsonpath='{.items[0].metadata.name}')
kubectl -n "$NAMESPACE" exec -it "$POD_NAME" /etc/openvpn/setup/revokeClientCert.sh $KEY_NAME

The entire list of helper scripts can be found on templates/config-openvpn.yaml

Be sure to change KEY_NAME if generating additional keys. Import the .ovpn file into your favorite openvpn tool like tunnelblick and verify connectivity.

Configuration

The following table lists the configurable parameters of the openvpn chart and their default values, and can be overwritten via the helm --set flag.

This chart has been engineered to use kube-dns and route all network traffic to kubernetes pods and services, to disable this behaviour set openvpn.OVPN_K8S_POD_NETWORK and openvpn.OVPN_K8S_POD_SUBNET to null.

If openvpn.OVPN_K8S_SVC_NETWORK and openvpn.OVPN_K8S_SVC_SUBNET are defined, an extra route for services subnet will be added.

Note: As configured the chart will create a route for a large 10.0.0.0/8 network that may cause issues if that is your local network. If so tweak this value to something more restrictive. This route is added, because GKE generates pods with IPs in this range.

Certificates

New certificates are generated with each deployment, if keystoreSecret is not defined. If persistence is enabled certificate data will be persisted across pod restarts. Otherwise new client certs will be needed after each deployment or pod restart.

Certificates can be passed in secret, which name is specified in openvpn.keystoreSecret value. Create secret as follows:

kubectl create secret generic openvpn-keystore-secret --from-file=./server.key --from-file=./ca.crt --from-file=./server.crt --from-file=./dh.pem [--from-file=./crl.pem] [--from-file=./ta.key]

You can deploy temporary openvpn chart, create secret from generated certificates, and then re-deploy openvpn, providing the secret. Certificates can be found in openvpn pod in the following files:

/etc/openvpn/certs/pki/private/server.key /etc/openvpn/certs/pki/ca.crt /etc/openvpn/certs/pki/issued/server.crt /etc/openvpn/certs/pki/dh.pem

If openvpn.useCrl is set:

/etc/openvpn/certs/pki/crl.pem

And optionally (see openvpn.taKey setting):

/etc/openvpn/certs/pki/ta.key

Note: using mounted secret makes creation of new client certificates impossible inside openvpn pod, since easyrsa needs to write in certs directory, which is read-only.

Client specific rules and access policies

You can enable CCD using openvpn.ccd.enabled and set the config in openvpn.ccd.config to use OpenVPN client specific rules and access policies

For example, if you want to give fixed IP addresses to clients 'johndoe' and 'janedoe':

openvpn:
  ccd:
    enabled: true
    config:
      johndoe: "ifconfig-push 10.240.100.10 10.240.100.11"
      janedoe: "ifconfig-push 10.240.100.20 10.240.100.21"

For more options see the OpenVPN documentation. Note that the IPs provided here depend on the type of topology you use.

Issues

1. Routing / ip_forward

Issue: https://github.com/helm/charts/issues/6398

If routes look correct on the client but data is not returning from the vpn then the kubernetes node running openvpn may not have ip_forward enabled. Set the ipForwardInitContainer value to true to run an init container that enables ip forwarding.

2. Ubuntu/systemd-resolved DNS

Recent Ubuntu releases use systemd-resolved for DNS which by default won't honor/apply DNS settings from openvpn.

Install the openvpn-systemd-resolved package (apt install openvpn-systemd-resolved) and add the following settings to the client ovpn file.

script-security 2
up /etc/openvpn/update-systemd-resolved
up-restart
down /etc/openvpn/update-systemd-resolved
down-pre
dhcp-option DOMAIN-ROUTE .

If all of your clients are Ubuntu you can set the openvpn.clientConf value when deploying this chart to have these lines added to all generated client ovpn files:

openvpn:
  clientConf: |
    script-security 2
    up /etc/openvpn/update-systemd-resolved
    up-restart
    down /etc/openvpn/update-systemd-resolved
    down-pre

3. Ubuntu Networking GUIs

Importing the client ovpn file from either of the Ubuntu network/connection management GUIs (Settings or Advanced Networking app) do not successfully import all settings. They seem to remove important parts of the configuration (DNS and Domains). The most reliable method of initiating the connection is to run sudo openvpn --config <FILE>.