[Question] Is external volumes still needed when using this ?

[blmhemu]

Caddy requires write access to two locations: a data directory, and a configuration directory.
While it's not necessary to persist the files stored in the configuration directory, it can be convenient. 
However, it's very important to persist the data directory.

The above snippet is from caddy docker readme.

Does this plugin make both these storage requirements redundant ?

[pteich]

With this plugin all data regarding certificates is saved in Consul's KV storage. You need to provide a Caddyfile that needs to be stored somewhere. But I am not aware of any other data that needs to be stored in a persistent way. At least I use Caddy with this plugin only for years now without mounting additional volumes to my Caddy Docker container.