ansible-pihole

Bootstrap a Raspberry Pi with Ansible and install Docker + Pi-hole

Optionally you can enable HA (high availability) with keepalived and sync settings between multiple instances.

The repository contains four Ansible Playbooks. Each one is described here shortly.

For more info about the Docker Pi-hole image please check the official repository: https://github.com/pi-hole/docker-pi-hole

Base Setup

• An Ansible controller machine with Ansible installed (version 2.10 or later)

• The openssh_keypair Ansible module installed.

• One or more Raspberry Pi's with Raspberry Pi OS Lite

• Headless setup (configuration before first boot):

  • Enable SSH "3. Enable SSH on a headless Raspberry Pi..."
  • Enable wireless networking or connect with LAN
    If you use LAN exclusively, consider disabling Wifi by adding dtoverlay=disable-wifi to /boot/config.txt

• Set static IPs for your Raspberry Pi's (static DHCP assignment/reservation in your Router/DHCP server is sufficient)

• Configure your targets (IPs of your Raspberry Pi's) and other settings in inventory.yaml
  You can add or remove hosts in the inventory, depending on how many Raspberry Pi's you use.

bootstrap-pihole.yaml

This playbook is for the first time run (but it can be rerun any time).
It will bootstrap a fresh Raspberry Pi OS installation, install Docker, and Pi-hole.
You can run it with: ansible-playbook -i inventory.yaml bootstrap-pihole.yaml

If the playbook fails during the first run while installing Docker, please reboot your Pi and re-run the playbook!

These roles are included:

• bootstrap: Some basic configuration
  • Add the ssh key fetched from your GitHub user, configured in github_user_for_ssh_key (Alternatively you can also set your ssh key directly here)
  • Lock the password to prevent local terminal login
  • Set some useful bash aliases
  • Set timezone, configured in timezone
  • Set hostname to the respective Ansible inventory_hostname
  • Set a static DNS server, configured in static_dns
• updates: Update apt packages
• sshd: Harden the sshd config
  • Disable root login
  • Disable password authentication
• docker: Install and configure Docker
• pihole: Start/Update Pi-hole container
  • Pi-hole container settings are configured in inventory.yaml
    The options prefixed with pihole_ are described in the official docker-pi-hole readme
    (except for pihole_image, pihole_ha_mode, pihole_vip_ipv4, pihole_vip_ipv6: those are custom variables of this playbook)
    The options prefixed with pihole_ftl_ are described in the official Pi-hole FTL Configuration
  • The pihole_ha_mode option is used to switch between HA or Single mode to determine the IPv4/IPv6 addresses for the Pi-hole services (bind IPs for Web/DNS, pi.hole DNS record) and is enabled by default.
    ⚠️ Disable this if you don't intend to deploy a HA setup with keepalived.

update-pihole.yaml

This playbook is for subsequent runs after the bootstrap-pihole.yaml playbook was run at least once.
You can run it with: ansible-playbook -i inventory.yaml update-pihole.yaml
It contains only a subset of roles for faster runtime: updates and pihole
This will keep the system up to date and can be used to roll out changes to the Pi-hole docker container, for example a new image version.

keepalived.yaml

This playbook enables a high availability failover cluster with keepalived between multiple Pi-hole instances.
You can run it with: ansible-playbook -i inventory.yaml keepalived.yaml

Motivation:

• Redundancy: Avoid a single point of failure (due to raspberry pi reboot, docker container failure/update/restart)
• Architecture of DNS requires a HA solution on the DNS server side (most clients will not properly handle unavailable DNS servers; if a client has multiple DNS servers configured it will try them one after another only moving on if one times out)
• Poor DNS query performance during system updates & docker image pulls (experienced on my Pi 3 Model B)

Since the version of keepalived and its dependencies in the Raspberry Pi OS buster sources is heavily outdated (and has some nasty bugs), the playbook will upgrade the system to Raspberry Pi OS bullseye which includes a more recent keepalived version.
As healthcheck, the status of the Pi-hole docker container is evaluated.
Communication happens over VRRP (Virtual Router Redundancy Protocol) which uses Multicast.
The priority of each Pi-hole can be configured in inventory.yaml, for example:

    pihole-1:
      ansible_host: 192.168.178.45
      priority: 101

The desired VIPs (Virtual IPs) for IPv4 and IPv6 can be configured in inventory.yaml:

    pihole_vip_ipv4: "192.168.178.10/24"
    pihole_vip_ipv6: "fd00::10/64"

When maintaining and updating your Pi-hole instances with the bootstrap-pihole.yaml and update-pihole.yaml playbooks, the first step stops keepalived and therefore shifts the VIP to another instance so that the performance of DNS queries is not impeded.

sync.yaml

This playbook enables the synchronisation of settings between multiple Pi-hole instances.
You can run it with: ansible-playbook -i inventory.yaml sync.yaml
One Pi-hole functions as the primary instance and the others as secondaries which pull from the primary.
Syncing is scheduled as a cronjob and set to run two times per day (frequency can be changed here).
What gets synced:

• gravity.db (Adlists, Domains, Clients, Groups, Group Assignments of all aforementioned items)
• custom.list (Local DNS Records)
• 05-pihole-custom-cname.conf (Local CNAME Records)

Default: Pull from VIP

If you enabled HA (high availability) with the keepalived.yaml playbook, the primary instance will be the one currently occupying the Virtual IP address (evaluated at each cronjob run).

sync_target: "{{ pihole_vip_ipv4.split('/')[0] }}"

Alternative: Pull from primary instance

You can set the sync_target variable to the IP address of your primary Pi-hole instance (in my example pihole-1, otherwise adapt).

sync_target: "{{ hostvars['pihole-1'].ansible_host }}"

For syncing, rsync is used which will only transfer files if they contain changes.
Changes to gravity.db will trigger a docker container restart to pick up the changes.
Changes to DNS & CNAME records get picked up on the fly.