[WIP] K8s update and runtime package changes (#895)

* First commit: outline of K8s runtime package

* Added poller. Added auto-updater into default runtime

* Added build and updated Poller interface

* Added comments and NewRuntime that accepts Options

* DefaultPoller; Runtime options

* First commit to add Kubernetes cruft

* Add comments

* Add micro- prefix to K8s runtime service names

* Get rid of import cycles. Move K8s runtime into main runtime package

* Major refactoring: Poller replaced by Notifier

POller has been replaced by Notifier which returns a channel of events
that can be consumed and acted upon.

* Added runtime configuration options

* K8s runtime is now Kubernetes runtime in dedicated pkg. Naming kung-fu.

* Fix typo in command.

* Fixed typo

* Dont Delete service when runtime stops.

runtime.Stop stops services; no need to double-stop

* Track runtime services

* Parse Unix timestamps properly

* Added deployments into K8s client. Debug logging

runtime/kubernetes/client/watch/watch_test.go

@@ -0,0 +1,71 @@
+package watch
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+var actions = []string{
+	`{"type": "create", "object":{"foo": "bar"}}`,
+	`{"type": "delete", INVALID}`,
+	`{"type": "update", "object":{"foo": {"foo": "bar"}}}`,
+	`{"type": "delete", "object":null}`,
+}
+
+func TestBodyWatcher(t *testing.T) {
+	// set up server with handler to flush strings from ch.
+	ch := make(chan string)
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		flusher, ok := w.(http.Flusher)
+		if !ok {
+			t.Fatal("expected ResponseWriter to be a flusher")
+		}
+
+		fmt.Fprintf(w, "\n")
+		flusher.Flush()
+
+		for v := range ch {
+			fmt.Fprintf(w, "%s\n", v)
+			flusher.Flush()
+			time.Sleep(10 * time.Millisecond)
+		}
+	}))
+	defer ts.Close()
+
+	req, err := http.NewRequest("GET", ts.URL, nil)
+	if err != nil {
+		t.Fatalf("did not expect NewRequest to return err: %v", err)
+	}
+
+	// setup body watcher
+	w, err := NewBodyWatcher(req, http.DefaultClient)
+	if err != nil {
+		t.Fatalf("did not expect NewBodyWatcher to return %v", err)
+	}
+
+	<-time.After(time.Second)
+
+	// send action strings in, and expect result back
+	ch <- actions[0]
+	if r := <-w.ResultChan(); r.Type != "create" {
+		t.Fatalf("expected result to be create")
+	}
+
+	ch <- actions[1] // should be ignored as its invalid json
+	ch <- actions[2]
+	if r := <-w.ResultChan(); r.Type != "update" {
+		t.Fatalf("expected result to be update")
+	}
+
+	ch <- actions[3]
+	if r := <-w.ResultChan(); r.Type != "delete" {
+		t.Fatalf("expected result to be delete")
+	}
+
+	// stop should clean up all channels.
+	w.Stop()
+	close(ch)
+}