Pi-hole on Fly.io served via Tailscale

How to do it:

1. Get set up with Fly.io (only install flyctl and create an account/login)
2. Get set up with Tailscale
3. Clone this repo
4. Run the command fly launch --name $APP_NAME --no-deploy and answer the prompts (pick your own $APP_NAME)
5. Create an auth key in Tailscale and copy it to clipboard
6. Run the command fly secrets set TAILSCALE_AUTHKEY=<paste auth key here>
7. Run the command fly deploy --remote-only
8. Test it out with dig @${APP_NAME}.fly.dev google.com
9. If $STEP-1 worked, get the IP address of the Tailscale interface (from the Tailscale admin) and set that as your DNS resolver (in /etc/resolv.conf, Advanced tab of macOS's Networking panel in System Preferences, iOS, etc.)

Reading/Reference:

• Pi-Hole Docker image
• Stuff Your Pi-Hole From Anywhere (Fly.io blog)
• Free, private pi-hole hosting with Fly.io and Tailscale
• Tailscale on fly.io (Tailscale docs)
• Need to use legacy iptables when adding Tailscale to Linux (GitHub issue comment)
• Trying to follow the "Fly-Hole" tutorial... (Fly.io forum post)
• Self-hosted RethinkDNS (Pi-Hole alternative)