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 below.

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 2.13 or later)

• The community.crypto Ansible collection installed

• The ansible.posix Ansible collection installed

• One or more Raspberry Pi's with Raspberry Pi OS Lite (64-bit) (bookworm)

• I recommend using the Raspberry Pi Imager for preparing your SD Cards since this easily allows the initial image configuration:

  • Set username and password
  • Configure Wireless LAN
  • Enable SSH (preferably use the option “Allow public-key authentication only”)

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

• Configure your hosts (IPs and user of your Raspberry Pi's) and other settings in the inventory.yaml

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
  • 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
• docker: Install and configure Docker
• pihole: Start/Update Pi-hole container
  • Pi-hole container settings are configured in inventory.yaml
    The options are described in the official docker-pi-hole readme and the official Pi-hole FTL Configuration

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)

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)
• pihole.toml (All settings, including local DNS Records and 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 will trigger a docker container restart to apply the changes.