Add watch capability to our client.

Next steps: Make an etcd watcher... decide on a state field for pods...
move the scheduler to its own binary.

pkg/client/request.go

@@ -18,15 +18,20 @@ package client
 
 import (
 	"bytes"
+	"encoding/json"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
 	"net/url"
 	"path"
+	"sync"
 	"time"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/watch"
 	"github.com/golang/glog"
 )
 
@@ -191,12 +196,7 @@ func (r *Request) PollPeriod(d time.Duration) *Request {
 	return r
 }
 
-// Do formats and executes the request. Returns the API object received, or an error.
+func (r *Request) finalURL() string {
-func (r *Request) Do() Result {
-	for {
-		if r.err != nil {
-			return Result{err: r.err}
-		}
 	finalURL := r.c.host + r.path
 	query := url.Values{}
 	if r.selector != nil {
@@ -209,7 +209,38 @@ func (r *Request) Do() Result {
 		}
 	}
 	finalURL += "?" + query.Encode()
-		req, err := http.NewRequest(r.verb, finalURL, r.body)
+	return finalURL
+}
+
+// Attempts to begin watching the requested location. Returns a watch.Interface, or an error.
+func (r *Request) Watch() (watch.Interface, error) {
+	if r.err != nil {
+		return nil, r.err
+	}
+	req, err := http.NewRequest(r.verb, r.finalURL(), r.body)
+	if err != nil {
+		return nil, err
+	}
+	if r.c.auth != nil {
+		req.SetBasicAuth(r.c.auth.User, r.c.auth.Password)
+	}
+	response, err := r.c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	if response.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("Got status: %v", response.StatusCode)
+	}
+	return newHTTPWatcher(response.Body), nil
+}
+
+// Do formats and executes the request. Returns the API object received, or an error.
+func (r *Request) Do() Result {
+	for {
+		if r.err != nil {
+			return Result{err: r.err}
+		}
+		req, err := http.NewRequest(r.verb, r.finalURL(), r.body)
 		if err != nil {
 			return Result{err: err}
 		}
@@ -262,3 +293,74 @@ func (r Result) Into(obj interface{}) error {
 func (r Result) Error() error {
 	return r.err
 }
+
+type httpWatcher struct {
+	source io.ReadCloser
+	result chan watch.Event
+	done   chan struct{}
+	sync.Mutex
+	stopped bool
+}
+
+func newHTTPWatcher(source io.ReadCloser) *httpWatcher {
+	hw := &httpWatcher{
+		source: source,
+		result: make(chan watch.Event),
+		done:   make(chan struct{}),
+	}
+	go hw.receive()
+	return hw
+}
+
+// Implements watch.Interface
+func (hw *httpWatcher) ResultChan() <-chan watch.Event {
+	return hw.result
+}
+
+// Implements watch.Interface
+func (hw *httpWatcher) Stop() {
+	hw.Lock()
+	defer hw.Unlock()
+	if !hw.stopped {
+		close(hw.done)
+		hw.stopped = true
+	}
+}
+
+// In a loop, read results from http, decode, and send down the result channel.
+func (hw *httpWatcher) receive() {
+	defer close(hw.result)
+	defer hw.source.Close()
+	defer util.HandleCrash()
+
+	decoder := json.NewDecoder(hw.source)
+
+	decoded := make(chan *api.WatchEvent)
+
+	// Read one at a time. Have to do this separately because Decode blocks and
+	// we want to wait on the done channel, too.
+	go func() {
+		defer util.HandleCrash()
+		for {
+			var got api.WatchEvent
+			err := decoder.Decode(&got)
+			if err != nil {
+				hw.Stop()
+				return
+			}
+			decoded <- &got
+		}
+	}()
+
+	for {
+		select {
+		case <-hw.done:
+			return
+		case got := <-decoded:
+			hw.result <- watch.Event{
+				Type:   got.Type,
+				Object: got.Object.Object,
+			}
+		}
+	}
+}

pkg/client/request_test.go

@@ -18,16 +18,20 @@ package client
 
 import (
 	"bytes"
+	"encoding/base64"
+	"encoding/json"
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
 	"reflect"
+	"strings"
 	"testing"
 	"time"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/watch"
 )
 
 func TestDoRequestNewWay(t *testing.T) {
@@ -303,3 +307,91 @@ func TestPolling(t *testing.T) {
 		f()
 	}
 }
+
+func authFromReq(r *http.Request) (*AuthInfo, bool) {
+	auth, ok := r.Header["Authorization"]
+	if !ok {
+		return nil, false
+	}
+
+	encoded := strings.Split(auth[0], " ")
+	if len(encoded) != 2 || encoded[0] != "Basic" {
+		return nil, false
+	}
+
+	decoded, err := base64.StdEncoding.DecodeString(encoded[1])
+	if err != nil {
+		return nil, false
+	}
+	parts := strings.Split(string(decoded), ":")
+	if len(parts) != 2 {
+		return nil, false
+	}
+	return &AuthInfo{User: parts[0], Password: parts[1]}, true
+}
+
+// checkAuth sets errors if the auth found in r doesn't match the expectation.
+// TODO: Move to util, test in more places.
+func checkAuth(t *testing.T, expect AuthInfo, r *http.Request) {
+	foundAuth, found := authFromReq(r)
+	if !found {
+		t.Errorf("no auth found")
+	} else if e, a := expect, *foundAuth; !reflect.DeepEqual(e, a) {
+		t.Fatalf("Wrong basic auth: wanted %#v, got %#v", e, a)
+	}
+}
+
+func TestWatch(t *testing.T) {
+	var table = []struct {
+		t   watch.EventType
+		obj interface{}
+	}{
+		{watch.Added, &api.Pod{JSONBase: api.JSONBase{ID: "first"}}},
+		{watch.Modified, &api.Pod{JSONBase: api.JSONBase{ID: "second"}}},
+		{watch.Deleted, &api.Pod{JSONBase: api.JSONBase{ID: "third"}}},
+	}
+
+	auth := AuthInfo{User: "user", Password: "pass"}
+	testServer := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		checkAuth(t, auth, r)
+		flusher, ok := w.(http.Flusher)
+		if !ok {
+			panic("need flusher!")
+		}
+
+		w.Header().Set("Transfer-Encoding", "chunked")
+		w.WriteHeader(http.StatusOK)
+		flusher.Flush()
+
+		encoder := json.NewEncoder(w)
+		for _, item := range table {
+			encoder.Encode(&api.WatchEvent{item.t, api.APIObject{item.obj}})
+			flusher.Flush()
+		}
+	}))
+
+	s := New(testServer.URL, &auth)
+
+	watching, err := s.Get().Path("path/to/watch/thing").Watch()
+	if err != nil {
+		t.Fatalf("Unexpected error")
+	}
+
+	for _, item := range table {
+		got, ok := <-watching.ResultChan()
+		if !ok {
+			t.Fatalf("Unexpected early close")
+		}
+		if e, a := item.t, got.Type; e != a {
+			t.Errorf("Expected %v, got %v", e, a)
+		}
+		if e, a := item.obj, got.Object; !reflect.DeepEqual(e, a) {
+			t.Errorf("Expected %v, got %v", e, a)
+		}
+	}
+
+	_, ok := <-watching.ResultChan()
+	if ok {
+		t.Fatal("Unexpected non-close")
+	}
+}

pkg/watch/watch.go

@@ -29,7 +29,7 @@ type Interface interface {
 	// Returns a chan which will receive all the events. If an error occurs
 	// or Stop() is called, this channel will be closed, in which case the
 	// watch should be completely cleaned up.
-	ResultChan() <-chan *Event
+	ResultChan() <-chan Event
 }
 
 // EventType defines the possible types of events.
@@ -52,14 +52,14 @@ type Event struct {
 
 // FakeWatcher lets you test anything that consumes a watch.Interface; threadsafe.
 type FakeWatcher struct {
-	result  chan *Event
+	result  chan Event
 	Stopped bool
 	sync.Mutex
 }
 
 func NewFake() *FakeWatcher {
 	return &FakeWatcher{
-		result: make(chan *Event),
+		result: make(chan Event),
 	}
 }
 
@@ -67,30 +67,32 @@ func NewFake() *FakeWatcher {
 func (f *FakeWatcher) Stop() {
 	f.Lock()
 	defer f.Unlock()
+	if !f.Stopped {
 		close(f.result)
 		f.Stopped = true
+	}
 }
 
-func (f *FakeWatcher) ResultChan() <-chan *Event {
+func (f *FakeWatcher) ResultChan() <-chan Event {
 	return f.result
 }
 
 // Add sends an add event.
 func (f *FakeWatcher) Add(obj interface{}) {
-	f.result <- &Event{Added, obj}
+	f.result <- Event{Added, obj}
 }
 
 // Modify sends a modify event.
 func (f *FakeWatcher) Modify(obj interface{}) {
-	f.result <- &Event{Modified, obj}
+	f.result <- Event{Modified, obj}
 }
 
 // Delete sends a delete event.
 func (f *FakeWatcher) Delete(lastValue interface{}) {
-	f.result <- &Event{Deleted, lastValue}
+	f.result <- Event{Deleted, lastValue}
 }
 
 // Action sends an event of the requested type, for table-based testing.
 func (f *FakeWatcher) Action(action EventType, obj interface{}) {
-	f.result <- &Event{action, obj}
+	f.result <- Event{action, obj}
 }