feat: Kubernetes service discovery

[clrxbl]

Surprising to see that this has not been implemented or mentioned anywhere yet (unless I'm blind) considering this project is all about being cloud-native.

https://github.com/itzg/mc-router#kubernetes-usage is a great example for forced hosts, but it'd be nice to expand this to Pod support aswell.

[robinbraemer]

Kubernetes's KRM can be a good configuration source for the Gate Lite mode.
Currently, Gate Lite only sources its configuration from the local configuration file.

To add this feature we can make use of the existing live config reload feature and a k8s adapter to update Gate config file to sync with Kubernetes resources.

I'll consider this feature request when I see more demand for it.

[Bloeckchengrafik]

To anyone who wants to implement this: I've just built something similar for one of my projects:

everbuild-org/prismcloud#images/ingress-gate/gate/plugin/service_discovery

[robinbraemer]

@Bloeckchengrafik you should post your tool in https://discord.com/channels/633708750032863232/1042460518595690526
and add it to https://github.com/minekube/awesome

[Bloeckchengrafik]

Thanks a lot for the suggestion! I'll do that when it becomes somewhat production ready!