Resolve ENV vars in labels

[ww-daniel-mora]

Is your feature request related to a problem? Please describe.
I would like to be able to reference environment variables in container labels for container deploys (type 1)

Describe the solution you'd like
Execute variable substitution in container labels.

Describe alternatives you've considered
Use docker-compose (type 3) with variables in the labels. This works and is just inconsistent with how labels are treated for type 1 deploys.

Additional context
Add any other context or screenshots about the feature request here.

[mariyam-portainer]

Hey, thanks for bringing this up. Just to understand where you are coming from, are you able to provide some more details on what you are trying to achieve? Also, could you please explain a little more why you are looking to use environment labels when you deploy a container?

[ww-daniel-mora]

Hey @mariyam-portainer . I was trying to create a Portainer container (type 1) template for an app behind the traefik reverse proxy, which uses labels as part of it's configuration. I cannot use a stack template because the app required access do devices that stacks do not support. I could not use a compose template because the docker engine is in swarm mode.

[huib-portainer]

So to recap, you created your own copy of the templates.json and placed that into your git repo.
And you're using Swarm, so normally you'd use a type 2 Swarm stack in that situation (because normally you'd want a service, not a single container). So the template would contain something like:

{
  "url": "https://github.com/example/templates",
  "stackfile": "stacks/docker-stack.yml"
}

But because docker service has no equivalent of --device (correct me if I'm wrong here), you're trying to define a container with labels. So the template would contain something like

{
  "labels": [
    { "name": "traefik.enable", "value": "true" },
    { "name": "traefik.http.routers.whoami.rule", "value": "Host(`192.168.189.130`)" },
    { "name": "traefik.http.routers.whoami.entrypoints", "value": "web" },
    { "name": "traefik.http.services.whoami.loadbalancer.server.port", "value": "80" }
  ]
}

And you want those values to be dynamic and provided when using the template, e.g. the template would contain something like:

"env": [{
		"name": "TRAEFIK_ROUTER_HOST",
		"label": "Host IP"
	}]

But there's no substitution happening, so you can't do something like:

{ "name": "traefik.http.routers.whoami.rule", "value": "Host(`${TRAEFIK_ROUTER_HOST}`)" }

[ww-daniel-mora]

Exactly correct @huib-portainer

[ww-daniel-mora]

For my specific situation it would also work if portainer displayed compose stacks in swarm mode when there are "attachable" overlay networks. Then I could use env substitution with the compose file.

That, of course, is an entirely different feature request! But I think it would also make sense to add to portainer and add coverage to new use cases and keep the user from needing to leave the tool.