Add support for swarm-mode (1.12)

[matthid]

Note: This is my first time doing go-programming, so please be kind :)

Will add some documentation on how to use this after I verified that it works for my use case. My plan is to integrate this into a swarm mode (1.12) cluster to be able to "hook" some domain suffixes to my containers (mainly for swarm internal tls certificate verification to work).

Note: #15 would be nice to have for my use-case as well :)

[matthid]

Maybe "type": "services", would be a better approach?

[matthid]

@tianon Let me know what you think. This is now working and in-use on my system.

[sergey-tikhonenko]

Hello, I'm looking for Swarm mode too, are you going to merge this?

[tianon]

Sorry for the really long delay, @matthid! I do like the idea of adding swarm support, but I agree that "type": "services" would make more sense -- the current "swarm" support was based on the legacy swarm mode where everything was still containers (and more importantly, was using the "container inspect" API), so switching to a completely separate type for looking up IP information for services makes sense (and makes it clear which API endpoint we need to hit, avoiding the docker inspect issue where it has to loop over API endpoints until it finds the right one).

If you've lost interest in this, I totally understand, and am happy to take over. ❤️

[matthid]

@tianon No, actually I'm glad to hear this is not dead. I even got a PR on my fork, but wasn't ready to take it (ie. fork this project - because of many other projects I'm involved).

We can continue with whatever is easier for you - either take over or tell me what to do to get it in (though I'm a absolute go beginner, but happy to learn :) )