Add Host to PodSpec and add a predicate to make the scheduler work.

pkg/scheduler/predicates.go

@@ -162,6 +162,13 @@ func (n *NodeSelector) PodSelectorMatches(pod api.Pod, existingPods []api.Pod, n
 	return selector.Matches(labels.Set(minion.Labels)), nil
 }
 
+func PodFitsHost(pod api.Pod, existingPods []api.Pod, node string) (bool, error) {
+	if len(pod.Spec.Host) == 0 {
+		return true, nil
+	}
+	return pod.Spec.Host == node, nil
+}
+
 func PodFitsPorts(pod api.Pod, existingPods []api.Pod, node string) (bool, error) {
 	existingPorts := getUsedPorts(existingPods...)
 	wantPorts := getUsedPorts(pod)

pkg/scheduler/predicates_test.go

@@ -124,6 +124,52 @@ func TestPodFitsResources(t *testing.T) {
 	}
 }
 
+func TestPodFitsHost(t *testing.T) {
+	tests := []struct {
+		pod  api.Pod
+		node string
+		fits bool
+		test string
+	}{
+		{
+			pod:  api.Pod{},
+			node: "foo",
+			fits: true,
+			test: "no host specified",
+		},
+		{
+			pod: api.Pod{
+				Spec: api.PodSpec{
+					Host: "foo",
+				},
+			},
+			node: "foo",
+			fits: true,
+			test: "host matches",
+		},
+		{
+			pod: api.Pod{
+				Spec: api.PodSpec{
+					Host: "bar",
+				},
+			},
+			node: "foo",
+			fits: false,
+			test: "host doesn't match",
+		},
+	}
+
+	for _, test := range tests {
+		result, err := PodFitsHost(test.pod, []api.Pod{}, test.node)
+		if err != nil {
+			t.Errorf("unexpected error: %v", err)
+		}
+		if result != test.fits {
+			t.Errorf("unexpected difference for %s: got: %v expected %v", test.test, test.fits, result)
+		}
+	}
+}
+
 func TestPodFitsPorts(t *testing.T) {
 	tests := []struct {
 		pod          api.Pod