Add integration test for build —cache-from

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

integration-cli/docker_cli_build_test.go

@@ -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])
+}