@@ -6931,3 +6931,96 @@ func (s *DockerSuite) TestBuildWithFailure(c *check.C) {

 	c.Assert(stdout, checker.Not(checker.Contains), "Step 1/2 : FROM busybox")

 	c.Assert(stdout, checker.Not(checker.Contains), "Step 2/2 : RUN nobody")

 }

+

+func (s *DockerSuite) TestBuildCacheFrom(c *check.C) {

+	testRequires(c, DaemonIsLinux) // All tests that do save are skipped in windows

+	dockerfile := `

+		FROM busybox

+		ENV FOO=bar

+		ADD baz /

+		RUN touch bax`

+	ctx, err := fakeContext(dockerfile, map[string]string{

+		"Dockerfile": dockerfile,

+		"baz":        "baz",

+	})

+	c.Assert(err, checker.IsNil)

+	defer ctx.Close()

+

+	id1, err := buildImageFromContext("build1", ctx, true)

+	c.Assert(err, checker.IsNil)

+

+	// rebuild with cache-from

+	id2, out, err := buildImageFromContextWithOut("build2", ctx, true, "--cache-from=build1")

+	c.Assert(err, checker.IsNil)

+	c.Assert(id1, checker.Equals, id2)

+	c.Assert(strings.Count(out, "Using cache"), checker.Equals, 3)

+	dockerCmd(c, "rmi", "build2")

+

+	// no cache match with unknown source

+	id2, out, err = buildImageFromContextWithOut("build2", ctx, true, "--cache-from=nosuchtag")

+	c.Assert(err, checker.IsNil)

+	c.Assert(id1, checker.Not(checker.Equals), id2)

+	c.Assert(strings.Count(out, "Using cache"), checker.Equals, 0)

+	dockerCmd(c, "rmi", "build2")

+

+	// clear parent images

+	tempDir, err := ioutil.TempDir("", "test-build-cache-from-")

+	if err != nil {

+		c.Fatalf("failed to create temporary directory: %s", tempDir)

+	}

+	defer os.RemoveAll(tempDir)

+	tempFile := filepath.Join(tempDir, "img.tar")

+	dockerCmd(c, "save", "-o", tempFile, "build1")

+	dockerCmd(c, "rmi", "build1")

+	dockerCmd(c, "load", "-i", tempFile)

+	parentID, _ := dockerCmd(c, "inspect", "-f", "{{.Parent}}", "build1")

+	c.Assert(strings.TrimSpace(parentID), checker.Equals, "")

+

+	// cache still applies without parents

+	id2, out, err = buildImageFromContextWithOut("build2", ctx, true, "--cache-from=build1")

+	c.Assert(err, checker.IsNil)

+	c.Assert(id1, checker.Equals, id2)

+	c.Assert(strings.Count(out, "Using cache"), checker.Equals, 3)

+	history1, _ := dockerCmd(c, "history", "-q", "build2")

+

+	// Retry, no new intermediate images

+	id3, out, err := buildImageFromContextWithOut("build3", ctx, true, "--cache-from=build1")

+	c.Assert(err, checker.IsNil)

+	c.Assert(id1, checker.Equals, id3)

+	c.Assert(strings.Count(out, "Using cache"), checker.Equals, 3)

+	history2, _ := dockerCmd(c, "history", "-q", "build3")

+

+	c.Assert(history1, checker.Equals, history2)

+	dockerCmd(c, "rmi", "build2")

+	dockerCmd(c, "rmi", "build3")

+	dockerCmd(c, "rmi", "build1")

+	dockerCmd(c, "load", "-i", tempFile)

+

+	// Modify file, everything up to last command and layers are reused

+	dockerfile = `

+		FROM busybox

+		ENV FOO=bar

+		ADD baz /

+		RUN touch newfile`

+	err = ioutil.WriteFile(filepath.Join(ctx.Dir, "Dockerfile"), []byte(dockerfile), 0644)

+	c.Assert(err, checker.IsNil)

+

+	id2, out, err = buildImageFromContextWithOut("build2", ctx, true, "--cache-from=build1")

+	c.Assert(err, checker.IsNil)

+	c.Assert(id1, checker.Not(checker.Equals), id2)

+	c.Assert(strings.Count(out, "Using cache"), checker.Equals, 2)

+

+	layers1Str, _ := dockerCmd(c, "inspect", "-f", "{{json .RootFS.Layers}}", "build1")

+	layers2Str, _ := dockerCmd(c, "inspect", "-f", "{{json .RootFS.Layers}}", "build2")

+

+	var layers1 []string

+	var layers2 []string

+	c.Assert(json.Unmarshal([]byte(layers1Str), &layers1), checker.IsNil)

+	c.Assert(json.Unmarshal([]byte(layers2Str), &layers2), checker.IsNil)

+

+	c.Assert(len(layers1), checker.Equals, len(layers2))

+	for i := 0; i < len(layers1)-1; i++ {

+		c.Assert(layers1[i], checker.Equals, layers2[i])

+	}

+	c.Assert(layers1[len(layers1)-1], checker.Not(checker.Equals), layers2[len(layers1)-1])

+}