Pihole On-top of UDM Pro

Here are some concise steps on how to step-by-step block ads on your network with pihole's DNS-level ad blocker.

Enabling SSH on UDM Pro

Go to 192.168.1.1 or wherever you're hosting your UDM Pro
Within "settings" cog, click on "system" tab
Click "enabled" on SSH near the bottom
Leverage "change password" button if you don't remember it

Log Into SSH & Get Unifi-OS Scripts

Open Terminal and ssh root@192.168.1.1 -o HostKeyAlgorithms=+ssh-rsa
Jump into Unifi shell with unifi-os shell
Download package curl -L https://udm-boot.boostchicken.dev -o udm-boot.deb
Install package dpkg -i udm-boot.deb
Enable boot script with systemctl enable udm-boot
Leave Unifi shell but stay within ssh with exit

Create Network Within UDM Web GUI

Create a pihole network with the following settings:

Host address (I used 192.168.3.0)
Netmask 24
VLAN ID (I used 8, just make sure it's a new one for you)
Network Type: Standard
Multicast DNS: Enabled
DHCP: none (pihole can handle this if you want)
IPv6: none

Setup Pihole Pod

download the dns.conflist template curl -L https://github.com/boostchicken-dev/udm-utilities/raw/master/cni-plugins/20-dns.conflist -o /mnt/data/podman/cni/dns.conflist
Open dns.conflist with vim and change "mac" line so last 3 portions are fake hex that would be unique to your network. Change address settings (Mine is 192.168.3.2/24) and gateway settings (Mine is 192.168.3.1). Change VLAN number such as "master": "br8".
Make sure dns.conflist is executable for podman with chmod +x /mnt/data/podman/cni/dns.conflist
Copy dns.conflist to its read directory so podman network can see it with cp /mnt/data/podman/cni/dns.conflist /etc/cni/net.d/dns.conflist
Validate dns.conflist is configured and working properly with podman network inspect dns
Download the install-sni-plugins script with curl -L https://github.com/unifi-utilities/unifios-utilities/blob/main/cni-plugins/05-install-cni-plugins.sh -o /mnt/data/on_boot.d/05-install-cni-plugins.sh
Add the executable flag to install-sni-plugins script with chmod +x /mnt/data/on_boot.d/05-install-cni-plugins.sh
Execute the install-sni-plugins script with /mnt/data/on_boot.d/05-install-cni-plugins.sh
Download the DNS configuration script with curl -L https://raw.githubusercontent.com/boostchicken-dev/udm-utilities/master/dns-common/on_boot.d/10-dns.sh -o /mnt/data/on_boot.d/10-dns.sh
Make the DNS configuration script executable with chmod +x /mnt/data/on_boot.d/10-dns.sh
Edit the script to change the IPV4_IP and IPV4_GW to reflect the address and gateway IP's used within step number 2
Execute the DNS configuration script with /mnt/data/on_boot.d/10-dns.sh
Create the directory structure for persistent pihole configuration with mkdir -p /mnt/data/etc-pihole and mkdir -p /mnt/data/pihole/etc-dnsmasq.d
Now create and run the pihole docker container with the following command:

podman run -d \
  --network dns \
  --restart always \
  --name pihole \
  -e TZ="America/Chicago" \
  --cap-add=NET_ADMIN \
  -v "/mnt/data/etc-pihole/:/etc/pihole/" \
  -v "/mnt/data/pihole/etc-dnsmasq.d/:/etc/dnsmasq.d/" \
  --dns=127.0.0.1 \
  --dns=1.1.1.1 \
  --dns=8.8.8.8 \
  --hostname pi.hole \
  -e VIRTUAL_HOST="pi.hole" \
  -e PROXY_LOCATION="pi.hole" \
  -e FTLCONF_REPLY_ADDR4="192.168.3.2" \
  -e ServerIP="192.168.3.2" \
  -e IPv6="False" \
  pihole/pihole:latest

This command tells podman to run a container leveraging the dns network we created, to always restart on crashes, mount the data volumes, primary supplementary and tertiary dns lookup values, default hostname and a variety of typical environment variables.

Last Couple Steps

Now it's a good idea to set your pihole password with podman exec -it pihole pihole -a -p Your$ecretPassw0rd
Update your router to now leverage the local VLAN DNS server. Within the UDM GUI it's under networks > advanced > DHCP Name Server although this has changed numerous times throughout versions of UDM Pro.