[trinovantes]

I'm currently reverse proxying a few docker containers with nginx. Caddy seems tempting but one dealbreaker I can't find in the docs is whether or not it automatically refreshes its DNS cache if a docker container restarts and changes its IP address?

e.g. In nginx, I use "resolver 127.0.0.11 valid=30s" so "proxy_pass {container}:80" will only cache the {container}'s IP address for 30s

[avianlyric]

From my experience I’ve not had any issues with Caddy using stale DNS entries when proxying Docker containers.

From the forums it looks like Caddy doesn’t explicitly define any DNS behaviour, it relies on Golangs defaults, which in turn simply uses whatever the host provides. I.e. whatever IP your host DNS resolution returns is used, and Caddy doesn’t cache internally, it relies on your hosts DNS cache. It’s reasonable to assume that any modern OS respects DNS TTL, and for something like Docker it’s gonna be doing a lookup on every request (which should be pretty much instant, as everything is on the same machine).

https://caddy.community/t/proxy-dns-resolver-mechanism/5934

https://stackoverflow.com/questions/40251727/does-go-cache-d...

[trinovantes]

Perfect, that's exactly what I'm looking for

[piaste]

If you want a slightly heavier but more robust solution, caddy-docker-proxy[0] is a plugin that listens to the Docker socket and automatically updates the Caddy configuration based on Docker labels you add to containers.

I.e. it makes Caddy act a bit more like Traefik. Most of the time, you'll just add the label `caddy.reverse_proxy={{upstreams http 8080}}` to your containers and the plugin will regenerate Caddy's configuration whenever the container is modified.

[0] https://github.com/lucaslorentz/caddy-docker-proxy