I can’t help you with automation. I update my containers manually, whenever I think to do it. Nothing is accessible outside my network so I’m not worried about staying on top of security updates.

You could just build it yourself, there’s not much to it.

Dockerfile:

ARG VERSION=2

FROM caddy:${VERSION}-builder AS builder

RUN xcaddy build \
    --with github.com/caddy-dns/cloudflare

FROM caddy:${VERSION}

COPY --from=builder /usr/bin/caddy /usr/bin/caddy

My Dockerfile is under dockerfile-dns and then in docker-compose.yaml instead of pointing to an image I have:

services:
  caddy:
    build: ./dockerfile-dns

I’m not 100% sure of the right way to update it, but I think I usually use something like docker compose build --pull --no-cache.