[Docker Swarm] : Environment variable in labels

[Necrelox]

Description

Hello,

I hope you’re doing well.

I’m using Docker Swarm, which I really appreciate overall.
However, I’ve run into an issue that, in my opinion, shouldn’t even exist today: it’s still impossible to use environment variables inside labels.

For example:

labels:
  - "my.label=${ENV_VARIABLE}"

Unfortunately, this kind of variable substitution is still not supported, even though it seems like a simple and extremely useful feature especially for things like Traefik.