Add k8s context

[dcramer]

Something I'm looking to evaluate and contribute back (in hopes that maybe we can standardize on a more correct/performant/useful SDK), is adding additional context/index capabilities.

Contexts look like this:

{
  // event payload
  "contexts": {
    "kubernetes": {
       "key": "value"
    }
  }
}

Eventually these will get auto-indexed like tags do, but right now we still have to send both tags (for search) and contexts for display. It's basically a more flexible version of 'extra' (since its just a namespaced extra).

I think for starters it'd be good to take every tag or generic object metadata and stuff it into the context.

[wichert]

That should be pretty easy to do. I already include labels as tags; is there much useful value in including them in the context as well?