yacht7/openvpn-client is a containerized OpenVPN client. It has a kill switch built with iptables that kills Internet connectivity to the container if the VPN tunnel goes down for any reason. It also includes two types of proxy: HTTP (Tinyproxy) and SOCKS5 (Shadowsocks). These allow hosts and non-containerized applications to use the VPN without having to run VPN clients on every host.

This image requires you to supply the necessary OpenVPN configuration file(s). Because of this, any VPN provider should work (however, if you find something that doesn't, please open an issue for it).

Having a containerized VPN client lets you use container networking to easily choose which applications you want using the VPN instead of having to set up split tunnelling. It also keeps you from having to install an OpenVPN client on the underlying host.

The idea for this image came from a similar project by qdm12 that has since evolved into something bigger and more complex than I wanted to use. I decided to dissect it and take it in my own direction. I plan to keep everything here well-documented because I want this to be a learning experience for both me and hopefully anyone else that uses it.

You can either pull it from Docker Hub or build it yourself.

To pull from Docker Hub, run docker pull yacht7/openvpn-client.

To build it yourself, do the following:

git clone https://github.com/yacht7/docker-openvpn-client.git
cd docker-openvpn-client
docker build -t yacht7/openvpn-client .

The image requires the container be created with the NET_ADMIN capability and /dev/net/tun accessible. Below are bare-bones examples for docker run and Compose; however, you'll probably want to do more than just run the VPN client. See the sections below to learn how to use the proxies and have other containers use openvpn-client's network stack.

docker run -d \
  --name=openvpn-client \
  --cap-add=NET_ADMIN \
  --device=/dev/net/tun \
  -v <path/to/config>:/data/vpn
  yacht7/openvpn-client

version: '2'

services:
    openvpn-client:
        image: yacht7/openvpn-client
        container_name: openvpn-client
        cap_add:
            - NET_ADMIN
        devices:
            - /dev/net/tun
        volumes:
            - <path/to/config>:/data/vpn
        restart: unless-stopped

The kill switch allows connections outside of the VPN tunnel to the following two places: 1) the VPN server(s) specified in the configuration file and 2) all addresses specified in SUBNETS.

Important: The DNS server used by this container prior to VPN connection must be included in the value specified. For example, if your container is using 192.168.1.1 as a DNS server, then this address or an appropriate CIDR block must be included in SUBNETS. This is necessary because the kill switch blocks traffic outside of the VPN tunnel before it's actually established. If the DNS server is not whitelisted, the server addresses in the VPN configuration will not resolve.

The subnets specified will have routes created and whitelists added in the firewall for them which allows for connectivity to and from hosts on the subnets.

If enabling Shadowsocks or Tinyproxy, you'll want to publish the proxy's port in order to access the proxy. To do that using docker run, add -p <host_port>:<container_port> where <host_port> and <container_port> are whatever port your proxy is using (8388 and 8888 by default for Shadowsocks and Tinyproxy). If you're using docker-compose, add the below snippet to the openvpn-client service definition in your Compose file.

ports:
    - <host_port>:<container_port>

Once you have your openvpn-client container up and running, you can tell other containers to use openvpn-client's network stack which gives them the ability to utilize the VPN tunnel. There are a few ways to accomplish this depending how how your container is created.

If your container is being created with

1. the same Compose YAML file as openvpn-client, add network_mode: service:openvpn-client to the container's service definition.
2. a different Compose YAML file than openvpn-client, add network_mode: container:openvpn-client to the container's service definition.
3. docker run, add --network=container:openvpn-client as an option to docker run.

Once running and provided your container has wget or curl, you can run docker exec <container_name> wget -qO - ifconfig.me or docker exec <container_name> curl -s ifconfig.me to get the public IP of the container and make sure everything is working as expected. This IP should match the one of openvpn-client.

If you have a connected container and you need to access a port that container, you'll want to publish that port on the openvpn-client container instead of the connected container. To do that, add -p <host_port>:<container_port> if you're using docker run, or add the below snippet to the openvpn-client service definition in your Compose file if using docker-compose.

ports:
    - <host_port>:<container_port>

In both cases, replace <host_port> and <container_port> with the port used by your connected container.

Once you have container running yacht7/openvpn-client, run the following command to spin up a temporary container using openvpn-client for networking. The wget -qO - ifconfig.me bit will return the public IP of the container (and anything else using openvpn-client for networking). You should see an IP address owned by your VPN provider.

docker run --rm -it --network=container:openvpn-client alpine wget -qO - ifconfig.me