Allow for watching of multiple paths in Consul KV

[benvanstaveren]

Welcome!

• Yes, I've searched similar issues on GitHub and didn't find any.
• Yes, I've searched similar issues on the Traefik community forum and didn't find any.

What did you expect to see?

Currently we store Traefik's dynamic configuration in Consul KV - this is fine when all Traefik instances share a configuration, but gets progressively more complicated when they don't. It leads to duplicating an entire configuration into a separate path, and making 1 or 2 changes.

It would be nice if we can specify the root path as an array/list of paths, from lowest to highest priority. For instance by setting:

providers:
  consulCatalog:
    prefix: 
    - traefik/common
    - traefik/specificinstance

Where the configuration is first retrieved from "traefik/common/" and then from "traefik/specificinstance/" with the latter's data overwriting the former. This allows for a bit more flexibility, in my opinion.

[ldez]

Duplicate of #7419

[benvanstaveren]

Not a duplicate - the alias functionality allows for switching to a new configuration for one traefik instance transparently, this would allow for multiple configurations to be loaded with some form of inheritance of configuration values.

[tfny]

Sorry about that, you are right, this is not a duplicate. During our sync today we decided that this is something we don't think we wish to include in Traefik Proxy right now, but we do think it is a candidate for a provider plug-in if you are interested in creating one.

Thanks!