schema/pod: ensure volume names are unique

The array "volumes" is indexed via the "name" field on each volume
object. This ensures that names are unique to avoid ambiguity in
mount-volume matching, by rejecting pod manifests containing
duplicate-named volumes.

schema/pod.go

@@ -83,6 +83,15 @@ func (pm *PodManifest) assertValid() error {
 	if pm.ACKind != PodManifestKind {
 		return pmKindError
 	}
+
+	// ensure volumes names are unique (unique key)
+	volNames := make(map[types.ACName]bool, len(pm.Volumes))
+	for _, vol := range pm.Volumes {
+		if volNames[vol.Name] {
+			return fmt.Errorf("duplicate volume name %q", vol.Name)
+		}
+		volNames[vol.Name] = true
+	}
 	return nil
 }
 

schema/pod_test.go

@@ -71,3 +71,43 @@ func TestAppList(t *testing.T) {
 		t.Errorf("want err, got nil")
 	}
 }
+
+func TestPodManifestUniqueVolumeNames(t *testing.T) {
+	pm := BlankPodManifest()
+	volA, err := types.VolumeFromString("simple,kind=empty")
+	if err != nil {
+		t.Errorf("expected nil error, got %q", err)
+	}
+	volB, err := types.VolumeFromString("simple,kind=host,source=/tmp")
+	if err != nil {
+		t.Errorf("expected nil error, got %q", err)
+	}
+	pm.Volumes = append(pm.Volumes, *volA, *volB)
+	if _, err := pm.MarshalJSON(); err == nil {
+		t.Errorf("expected duplicate volume name error, got nil")
+	}
+
+	pmj := `
+{
+        "acVersion": "0.8.10",
+        "acKind": "PodManifest",
+        "apps": [
+        ],
+        "volumes": [
+                {
+                        "name": "simplename",
+                        "kind": "empty"
+                },
+                {
+                        "name": "simplename",
+                        "kind": "host",
+                        "source": "/tmp"
+                }
+        ]
+}
+`
+	err = pm.UnmarshalJSON([]byte(pmj))
+	if err == nil {
+		t.Errorf("expected duplicate volume name error, got nil")
+	}
+}