Merge pull request #1496 from xdissent/1351-volumes-from-before-volumes

* Runtime: Apply volumes-from before creating volumes

container.go

@@ -577,14 +577,38 @@ func (container *Container) Start(hostConfig *HostConfig) error {
 		binds[path.Clean(dst)] = bindMap
 	}
 
-	// FIXME: evaluate volumes-from before individual volumes, so that the latter can override the former.
-	// Create the requested volumes volumes
 	if container.Volumes == nil || len(container.Volumes) == 0 {
 		container.Volumes = make(map[string]string)
 		container.VolumesRW = make(map[string]bool)
+	}
 
+	// Apply volumes from another container if requested
+	if container.Config.VolumesFrom != "" {
+		c := container.runtime.Get(container.Config.VolumesFrom)
+		if c == nil {
+			return fmt.Errorf("Container %s not found. Impossible to mount its volumes", container.ID)
+		}
+		for volPath, id := range c.Volumes {
+			if _, exists := container.Volumes[volPath]; exists {
+				continue
+			}
+			if err := os.MkdirAll(path.Join(container.RootfsPath(), volPath), 0755); err != nil {
+				return nil
+			}
+			container.Volumes[volPath] = id
+			if isRW, exists := c.VolumesRW[volPath]; exists {
+				container.VolumesRW[volPath] = isRW
+			}
+		}
+	}
+
+	// Create the requested volumes if they don't exist
 	for volPath := range container.Config.Volumes {
 		volPath = path.Clean(volPath)
+		// Skip existing volumes
+		if _, exists := container.Volumes[volPath]; exists {
+			continue
+		}
 		// If an external bind is defined for this volume, use that as a source
 		if bindMap, exists := binds[volPath]; exists {
 			container.Volumes[volPath] = bindMap.SrcPath
@@ -609,26 +633,6 @@ func (container *Container) Start(hostConfig *HostConfig) error {
 			return nil
 		}
 	}
-	}
-
-	if container.Config.VolumesFrom != "" {
-		c := container.runtime.Get(container.Config.VolumesFrom)
-		if c == nil {
-			return fmt.Errorf("Container %s not found. Impossible to mount its volumes", container.ID)
-		}
-		for volPath, id := range c.Volumes {
-			if _, exists := container.Volumes[volPath]; exists {
-				return fmt.Errorf("The requested volume %s overlap one of the volume of the container %s", volPath, c.ID)
-			}
-			if err := os.MkdirAll(path.Join(container.RootfsPath(), volPath), 0755); err != nil {
-				return nil
-			}
-			container.Volumes[volPath] = id
-			if isRW, exists := c.VolumesRW[volPath]; exists {
-				container.VolumesRW[volPath] = isRW
-			}
-		}
-	}
 
 	if err := container.generateLXCConfig(); err != nil {
 		return err

container_test.go

@@ -1283,6 +1283,71 @@ func TestRestartWithVolumes(t *testing.T) {
 	}
 }
 
+// Test for #1351
+func TestVolumesFromWithVolumes(t *testing.T) {
+	runtime := mkRuntime(t)
+	defer nuke(runtime)
+
+	container, err := NewBuilder(runtime).Create(&Config{
+		Image:   GetTestImage(runtime).ID,
+		Cmd:     []string{"sh", "-c", "echo -n bar > /test/foo"},
+		Volumes: map[string]struct{}{"/test": {}},
+	},
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer runtime.Destroy(container)
+
+	for key := range container.Config.Volumes {
+		if key != "/test" {
+			t.Fail()
+		}
+	}
+
+	_, err = container.Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := container.Volumes["/test"]
+	if expected == "" {
+		t.Fail()
+	}
+
+	container2, err := NewBuilder(runtime).Create(
+		&Config{
+			Image:       GetTestImage(runtime).ID,
+			Cmd:         []string{"cat", "/test/foo"},
+			VolumesFrom: container.ID,
+			Volumes:     map[string]struct{}{"/test": {}},
+		},
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer runtime.Destroy(container2)
+
+	output, err := container2.Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if string(output) != "bar" {
+		t.Fail()
+	}
+
+	if container.Volumes["/test"] != container2.Volumes["/test"] {
+		t.Fail()
+	}
+
+	// Ensure it restarts successfully
+	_, err = container2.Output()
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestOnlyLoopbackExistsWhenUsingDisableNetworkOption(t *testing.T) {
 	runtime := mkRuntime(t)
 	defer nuke(runtime)