ansible-role-wireguard

This Ansible role is used in my blog series Kubernetes the not so hard way with Ansible but can be used standalone of course. I use WireGuard and this Ansible role to setup a fully meshed VPN between all nodes of my little Kubernetes cluster. This VPN also includes two clients so that I can communicate securly with the Kubernetes API server. Also my Postfix mailserver running as K8s DaemonSet forwards mails to my internal Postfix through WireGuard VPN.

I used PeerVPN before but that wasn't updated for a while. As I moved my cloud hosts from Scaleway to Hetzner cloud it was a good time to switch the VPN solution ;-) In general PeerVPN still works perfectly fine esp. if you need a easy to setup fully meshed network (where every node is able to talk to all other nodes and even if node A should be able to talk to Node C via node B ;-) ). But PeerVPN needs also lot of CPU resources and throuhput could be better. That's solved with WireGuard.

In general WireGuard is a network tunnel (VPN) for IPv4 and IPv6 that uses UDP. If you need more information about WireGuard you can find a good introduction here: Installing WireGuard, the Modern VPN.

This role was tested with Ubuntu 18.04 (Bionic Beaver) and Archlinux. It might also work with Ubuntu 16.04 (Xenial Xerus) but haven't tested it. If someone tested it let me please know if it works ;-)

Versions

I tag every release and try to stay with semantic versioning. If you want to use the role I recommend to checkout the latest tag. The master branch is basically development while the tags mark stable releases. But in general I try to keep master in good shape too.

Requirements

By default port 51820 (protocol UDP) should be accessable from the outside. But you can adjust the port by changing the variable wireguard_port. Also IP forwarding needs to be enabled e.g. via echo 1 > /proc/sys/net/ipv4/ip_forward . I decided not to implement this task in this Ansible role. IMHO that should be handled elsewhere. You can use my ansible-role-harden-linux e.g. Besides changing sysctl entries (which you need to enable IP forwarding) it also manages firewall settings among other things.

Changelog

see CHANGELOG.md

Role Variables

This variables can be changed in group_vars/:

# The LOCAL directory where the WireGuard certificates are stored after they
# were generated. By default this will expand to user's LOCAL ${HOME}
# (the user that run's "ansible-playbook" command) plus
# "/wireguard/certs". That means if the user's ${HOME} directory is e.g.
# "/home/da_user" then "wireguard_cert_directory" will have a value of
# "/home/da_user/wireguard/certs". If you change this make sure that
# the parent directory is writable by the user that runs "ansible-playbook"
# command.
wireguard_cert_directory: "{{ '~/wireguard/certs' | expanduser }}"
wireguard_cert_owner: "root"
wireguard_cert_group: "root"

# Directory to store WireGuard configuration on the remote hosts
wireguard_remote_directory: "/etc/wireguard"

# The port WireGuard will listen on.
wireguard_port: "51820"

# The interface name that wireguard should use.
wireguard_interface: "wg0"

The following variable is mandatory and needs to be configured for every host in host_vars/:

wireguard_address: "10.3.0.101/24"

Of course all IP's should be in the same subnet like /24 we see in the example above. If wireguard_allowed_ips is not set then the default value is the value from wireguard_address without the CIDR but instead with /32 which is basically a host route (have a look templates/wg.conf.j2). Let's see this example and let's assume you don't set wireguard_allowed_ips explicitly:

[Interface]
Address = 10.8.0.2/24
PrivateKey = ....
ListenPort = 51820

[Peer]
PrivateKey = ....
AllowedIPs = 10.8.0.101/32
Endpoint = controller01.p.domain.tld:51820

This is part of the WireGuard config from my workstation. It has the VPN IP 10.8.0.2 and we've a /24 subnet in which all my WireGuard hosts are located. Also you can see we've a peer here that has the endpoint controller01.p.domain.tld:51820. When wireguard_allowed_ips is not explicitly set the Ansible template will add an AllowedIPs entry with the IP of that host plus /32. In WireGuard this basically specifies the routing. The config above says: On my workstation with the IP 10.8.0.2 I want send all traffic to 10.8.0.101/32 to the endpoint controller01.p.domain.tld:51820. Now let's assume we set wireguard_allowed_ips: "0.0.0.0/0". Then the resulting config looks like this.

[Interface]
Address = 10.8.0.2/24
PrivateKey = ....
ListenPort = 51820

[Peer]
PrivateKey = ....
AllowedIPs = 0.0.0.0/0
Endpoint = controller01.p.domain.tld:51820

Now this is basically the same as above BUT now the config says: I want to route EVERY traffic originating from my workstation to the endpoint controller01.p.domain.tld:51820. If that endpoint can handle the traffic is of course another thing and it's up to you how you configure the endpoint routing ;-)

You can specify further optional settings (they don't have a default and won't be set if not specified besides wireguard_allowed_ips as already mentioned) also per host in host_vars/ (or in your Ansible hosts file if you like):

wireguard_allowed_ips: ""
wireguard_endpoint: "host1.domain.tld"
wireguard_persistent_keepalive: "30"
wireguard_dns: "1.1.1.1"
wireguard_postup: "..."
wireguard_postdown: "..."
wireguard_save_config: "true"

wireguard_address is required as already mentioned. It's the IP of the interface name defined with wireguard_interface variable (wg0 by default). Every host needs a unique VPN IP of course. If you don't set wireguard_endpoint the playbook will use the hostname defined in the vpn hosts group (the Ansible inventory hostname). If you set wireguard_endpoint to "" (empty string) that peer won't have a endpoint. That means that this host can only access hosts that have a wireguard_endpoint. That's useful for clients that don't expose any services to the VPN and only want to access services on other hosts. So if you only define one host with wireguard_endpoint set and all other hosts have wireguard_endpoint set to "" (empty string) that basically means you've only clients besides one which in that case is the WireGuard server. The third possibility is to set wireguard_endpoint to some hostname. E.g. if you have different hostnames for the private and public DNS of that host and need different DNS entries, for that case setting wireguard_endpoint becomes handy. Take for example the IP above: wireguard_address: "10.3.0.101". That's a private IP and I've created a DNS entry for that private IP like host01.i.domain.tld (i for internal that case). For the public IP I've created a DNS entry like host01.p.domain.tld (p for public). The wireguard_endpoint needs to be a interface that the other members in the vpn group can connect to. So in that case I would set wireguard_endpoint to host01.p.domain.tld because WireGuard normally needs to be able to connect to the public IP of the other host(s).

Here is a litte example for what I use the playbook: I use WireGuard to setup a fully meshed VPN (every host can directly connect to every other host) and run my Kubernetes (K8s) cluster at Hetzner Cloud (but you should be able to use any hoster you want). So the important components like the K8s controller and worker nodes (which includes the pods) only communicate via encrypted WireGuard VPN. Also (as already) mentioned I've two clients. Both have kubectl installed and are able to talk to the internal Kubernetes API server by using WireGuard VPN. One of the two clients also exposes a WireGuard endpoint because the Postfix mailserver in the cloud and my internal Postfix needs to be able to talk to each other. I guess that's maybe a not so common use case for WireGuard :D But it shows what's possible. So let me explain the setup which might help you to use this Ansible role.

First, here is a part of my Ansible hosts file:

[vpn]
controller0[1:3].i.domain.tld
worker0[1:2].i.domain.tld
server.at.home.i.domain.tld
workstation.i.domain.tld

[k8s_controller]
controller0[1:3].i.domain.tld

[k8s_worker]
worker0[1:2].i.domain.tld

As you can see I've three gropus here: vpn (all hosts on that will get WireGuard installed), k8s_controller (the Kubernetes controller nodes) and k8s_worker (the Kubernetes worker nodes). The i in the domainname is for internal. All the i.domain.tld DNS entries have a A record that points to the WireGuard IP that we define shortly for every host e.g.: controller01.i.domain.tld. IN A 10.8.0.101. The reason for that is that all Kubernetes components only binds and listen on the WireGuard interface in my setup. And since I need this internal IPs for all my Kubernetes components I specify the internal DNS entries in my Ansible hosts file. That way I can use the Ansible inventory hostnames and variables very easy in the playbooks and templates.

For the Kubernetes controller nodes I've defined the following host variables:

Ansible host file: host_vars/controller01.i.domain.tld

---
wireguard_address: "10.8.0.101/24"
wireguard_endpoint: "controller01.p.domain.tld"
ansible_host: "controller01.p.domain.tld"
ansible_python_interpreter: /usr/bin/python3

Ansible host file: host_vars/controller02.i.domain.tld:

---
wireguard_address: "10.8.0.102/24"
wireguard_endpoint: "controller02.p.domain.tld"
ansible_host: "controller02.p.domain.tld"
ansible_python_interpreter: /usr/bin/python3

Ansible host file: host_vars/controller03.i.domain.tld:

---
wireguard_address: "10.8.0.103/24"
wireguard_endpoint: "controller03.p.domain.tld"
ansible_host: "controller03.p.domain.tld"
ansible_python_interpreter: /usr/bin/python3

I've specified ansible_python_interpreter here for every node as the controller nodes use Ubuntu 18.04 which has Python 3 installed by default. ansible_host is set to the public DNS of that host. Ansible will use this hostname to connect to the host via SSH. I use the same value also for wireguard_endpoint because of the same reason. The WireGuard peers needs to connect to the other peers via a public IP (well at least via a IP that the WireGuard hosts can connect to - that could be of course also a internal IP if it works for you). The wireguard_address needs to be unique of course for every host.

For the Kubernetes worker I've defined the following variables:

Ansible host file: host_vars/worker01.i.domain.tld

---
wireguard_address: "10.8.0.111/24"
wireguard_endpoint: "worker01.p.domain.tld"
wireguard_persistent_keepalive: "30"
ansible_host: "worker01.p.domain.tld"
ansible_python_interpreter: /usr/bin/python3

Ansible host file: host_vars/worker02.i.domain.tld:

---
wireguard_address: "10.8.0.112/24"
wireguard_endpoint: "worker02.p.domain.tld"
wireguard_persistent_keepalive: "30"
ansible_host: "worker02.p.domain.tld"
ansible_python_interpreter: /usr/bin/python3

As you can see the variables are basically the same as the controller nodes have with one exception: wireguard_persistent_keepalive: "30". My worker nodes (at Hetzner Cloud) and my internal server (my server at home) are connected because I've running Postfix at my cloud nodes and the external Postfix server forwards the received mails to my internal server (and vice versa). I needed the keepalive setting because from time to time the cloud instances and the internal server lost connection and this setting solved the problem. The reason for this is of course because my internal server is behind NAT and the firewall/router must keep the NAT/firewall mapping valid (NAT and Firewall Traversal Persistence).

For my internal server at home (connected via DSL router to the internet) we've this configuration:

---
wireguard_address: "10.8.0.1/24"
wireguard_endpoint: "server.at.home.p.domain.tld"
wireguard_persistent_keepalive: "30"
ansible_host: 192.168.2.254
ansible_port: 22

By default the SSH daemon is listening on a different port than 22 on all of my public nodes but internally I use 22 and that's the reason to set ansible_port: 22 here. Also ansible_host is of course a internal IP for that host. The wireguard_endpoint value is a dynamic DNS entry. Since my IP at home isn't static I need to run a script every minute at my home server that checks if the IP has changed and if so adjusts my DNS record. I use OVH's DynHost feature to accomplish this but you can use and DynDNS provider you want of course. Also I forward incoming traffic on port 51820/UDP to my internal server to allow incoming WireGuard traffic. The wireguard_address needs to be of course part of our WireGuard subnet.

And finally for my workstation (on which I run all ansible-playbook commands):

wireguard_address: "10.8.0.2/24"
wireguard_endpoint: ""
ansible_connection: local
ansible_become: false

As you can see wireguard_endpoint: "" is a empty string here. That means the Ansible role won't set an endpoint for my workstation. Since there is no need for the other hosts to connect to my workstation it doesn't makes sense to have a endpoint defined. So in this case I can access all hosts defined in the Ansible group vpn from my workstation but not the other way round. So the resulting WireGuard config for my workstation looks like this:

[Interface]
Address = 10.8.0.2/24
PrivateKey = ....
ListenPort = 51820

[Peer]
PrivateKey = ....
AllowedIPs = 10.8.0.101/32
Endpoint = controller01.p.domain.tld:51820

[Peer]
PrivateKey = ....
AllowedIPs = 10.8.0.102/32
Endpoint = controller02.p.domain.tld:51820

[Peer]
PrivateKey = ....
AllowedIPs = 10.8.0.103/32
Endpoint = controller03.p.domain.tld:51820

[Peer]
PrivateKey = ....
AllowedIPs = 10.8.0.111/32
PersistentKeepalive = 30
Endpoint = worker01.p.domain.tld:51820

[Peer]
PrivateKey = ....
AllowedIPs = 10.8.0.112/32
PersistentKeepalive = 30
Endpoint = worker02.p.domain.tld:51820

[Peer]
PrivateKey = ....
AllowedIPs = 10.8.0.1/32
PersistentKeepalive = 30
Endpoint = server.at.home.p.domain.tld:51820

The other WireGuard config files (wg0.conf by default) looks similar but of course [Interface] includes the config of that specific host and the [Peer] entries lists the config of the other hosts.

Example Playbook

- hosts: vpn
  roles:
    - wireguard

License

GNU GENERAL PUBLIC LICENSE Version 3

Author Information

http://www.tauceti.blog