kaniko/integration/integration_test.go

/*
Copyright 2018 Google LLC

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package integration

import (
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"math"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"

	"github.com/google/go-containerregistry/pkg/name"
	"github.com/google/go-containerregistry/pkg/v1/daemon"
	"github.com/pkg/errors"

	"github.com/GoogleContainerTools/kaniko/pkg/timing"
	"github.com/GoogleContainerTools/kaniko/pkg/util"
	"github.com/GoogleContainerTools/kaniko/testutil"
)

var config *integrationTestConfig
var imageBuilder *DockerFileBuilder
var allDockerfiles []string

const (
	daemonPrefix       = "daemon://"
	integrationPath    = "integration"
	dockerfilesPath    = "dockerfiles"
	emptyContainerDiff = `[
     {
       "Image1": "%s",
       "Image2": "%s",
       "DiffType": "File",
       "Diff": {
	 	"Adds": null,
	 	"Dels": null,
	 	"Mods": null
       }
     },
     {
       "Image1": "%s",
       "Image2": "%s",
       "DiffType": "Metadata",
       "Diff": {
	 	"Adds": [],
	 	"Dels": []
       }
     }
   ]`
)

func getDockerMajorVersion() int {
	out, err := exec.Command("docker", "version", "--format", "{{.Server.Version}}").Output()
	if err != nil {
		log.Fatal("Error getting docker version of server:", err)
	}
	versionArr := strings.Split(string(out), ".")

	ver, err := strconv.Atoi(versionArr[0])
	if err != nil {
		log.Fatal("Error getting docker version of server during parsing version string:", err)
	}
	return ver
}
func launchTests(m *testing.M) (int, error) {

	if config.isGcrRepository() {
		contextFile, err := CreateIntegrationTarball()
		if err != nil {
			return 1, errors.Wrap(err, "Failed to create tarball of integration files for build context")
		}

		fileInBucket, err := UploadFileToBucket(config.gcsBucket, contextFile, contextFile)
		if err != nil {
			return 1, errors.Wrap(err, "Failed to upload build context")
		}

		if err = os.Remove(contextFile); err != nil {
			return 1, errors.Wrap(err, fmt.Sprintf("Failed to remove tarball at %s", contextFile))
		}

		RunOnInterrupt(func() { DeleteFromBucket(fileInBucket) })
		defer DeleteFromBucket(fileInBucket)
	}
	if err := buildRequiredImages(); err != nil {
		return 1, errors.Wrap(err, "Error while building images")
	}

	imageBuilder = NewDockerFileBuilder()

	return m.Run(), nil
}

func TestMain(m *testing.M) {
	var err error
	if !meetsRequirements() {
		fmt.Println("Missing required tools")
		os.Exit(1)
	}

	if allDockerfiles, err = FindDockerFiles(dockerfilesPath); err != nil {
		fmt.Println("Coudn't create map of dockerfiles", err)
		os.Exit(1)
	} else {
		config = initIntegrationTestConfig()
		exitCode, err := launchTests(m)
		if err != nil {
			fmt.Println(err)
		}
		os.Exit(exitCode)
	}

}

func buildRequiredImages() error {
	setupCommands := []struct {
		name    string
		command []string
	}{
		{
			name:    "Building kaniko image",
			command: []string{"docker", "build", "-t", ExecutorImage, "-f", "../deploy/Dockerfile", ".."},
		},
		{
			name:    "Building cache warmer image",
			command: []string{"docker", "build", "-t", WarmerImage, "-f", "../deploy/Dockerfile_warmer", ".."},
		},
		{
			name:    "Building onbuild base image",
			command: []string{"docker", "build", "-t", config.onbuildBaseImage, "-f", fmt.Sprintf("%s/Dockerfile_onbuild_base", dockerfilesPath), "."},
		},
		{
			name:    "Pushing onbuild base image",
			command: []string{"docker", "push", config.onbuildBaseImage},
		},
		{
			name:    "Building hardlink base image",
			command: []string{"docker", "build", "-t", config.hardlinkBaseImage, "-f", fmt.Sprintf("%s/Dockerfile_hardlink_base", dockerfilesPath), "."},
		},
		{
			name:    "Pushing hardlink base image",
			command: []string{"docker", "push", config.hardlinkBaseImage},
		},
	}

	for _, setupCmd := range setupCommands {
		fmt.Println(setupCmd.name)
		cmd := exec.Command(setupCmd.command[0], setupCmd.command[1:]...)
		if out, err := RunCommandWithoutTest(cmd); err != nil {
			return errors.Wrap(err, fmt.Sprintf("%s failed: %s", setupCmd.name, string(out)))
		}
	}
	return nil
}

func TestRun(t *testing.T) {
	for _, dockerfile := range allDockerfiles {
		t.Run("test_"+dockerfile, func(t *testing.T) {
			dockerfile := dockerfile
			t.Parallel()
			if _, ok := imageBuilder.DockerfilesToIgnore[dockerfile]; ok {
				t.SkipNow()
			}
			if _, ok := imageBuilder.TestCacheDockerfiles[dockerfile]; ok {
				t.SkipNow()
			}

			buildImage(t, dockerfile, imageBuilder)

			dockerImage := GetDockerImage(config.imageRepo, dockerfile)
			kanikoImage := GetKanikoImage(config.imageRepo, dockerfile)

			diff := containerDiff(t, daemonPrefix+dockerImage, kanikoImage, "--no-cache")

			expected := fmt.Sprintf(emptyContainerDiff, dockerImage, kanikoImage, dockerImage, kanikoImage)
			checkContainerDiffOutput(t, diff, expected)

		})
	}

	err := logBenchmarks("benchmark")
	if err != nil {
		t.Logf("Failed to create benchmark file: %v", err)
	}
}

func getGitRepo() string {
	var branch, repoSlug string
	if _, ok := os.LookupEnv("TRAVIS"); ok {
		if os.Getenv("TRAVIS_PULL_REQUEST") != "false" {
			branch = os.Getenv("TRAVIS_PULL_REQUEST_BRANCH")
			repoSlug = os.Getenv("TRAVIS_PULL_REQUEST_SLUG")
			log.Printf("Travis CI Pull request source repo: %s branch: %s\n", repoSlug, branch)
		} else {
			branch = os.Getenv("TRAVIS_BRANCH")
			repoSlug = os.Getenv("TRAVIS_REPO_SLUG")
			log.Printf("Travis CI repo: %s branch: %s\n", repoSlug, branch)
		}
		return "github.com/" + repoSlug + "#refs/heads/" + branch
	}
	return "github.com/GoogleContainerTools/kaniko"
}

func TestGitBuildcontext(t *testing.T) {
	repo := getGitRepo()
	dockerfile := fmt.Sprintf("%s/%s/Dockerfile_test_run_2", integrationPath, dockerfilesPath)

	// Build with docker
	dockerImage := GetDockerImage(config.imageRepo, "Dockerfile_test_git")
	dockerCmd := exec.Command("docker",
		append([]string{"build",
			"-t", dockerImage,
			"-f", dockerfile,
			repo})...)
	out, err := RunCommandWithoutTest(dockerCmd)
	if err != nil {
		t.Errorf("Failed to build image %s with docker command %q: %s %s", dockerImage, dockerCmd.Args, err, string(out))
	}

	// Build with kaniko
	kanikoImage := GetKanikoImage(config.imageRepo, "Dockerfile_test_git")
	dockerRunFlags := []string{"run", "--net=host"}
	dockerRunFlags = addServiceAccountFlags(dockerRunFlags, config.serviceAccount)
	dockerRunFlags = append(dockerRunFlags, ExecutorImage,
		"-f", dockerfile,
		"-d", kanikoImage,
		"-c", fmt.Sprintf("git://%s", repo))

	kanikoCmd := exec.Command("docker", dockerRunFlags...)

	out, err = RunCommandWithoutTest(kanikoCmd)
	if err != nil {
		t.Errorf("Failed to build image %s with kaniko command %q: %v %s", dockerImage, kanikoCmd.Args, err, string(out))
	}

	diff := containerDiff(t, daemonPrefix+dockerImage, kanikoImage, "--no-cache")

	expected := fmt.Sprintf(emptyContainerDiff, dockerImage, kanikoImage, dockerImage, kanikoImage)
	checkContainerDiffOutput(t, diff, expected)
}

func TestGitBuildcontextSubPath(t *testing.T) {
	repo := getGitRepo()
	dockerfile := "Dockerfile_test_run_2"

	// Build with docker
	dockerImage := GetDockerImage(config.imageRepo, "Dockerfile_test_git")
	dockerCmd := exec.Command("docker",
		append([]string{
			"build",
			"-t", dockerImage,
			"-f", dockerfile,
			repo + ":" + filepath.Join(integrationPath, dockerfilesPath),
		})...)
	out, err := RunCommandWithoutTest(dockerCmd)
	if err != nil {
		t.Errorf("Failed to build image %s with docker command %q: %s %s", dockerImage, dockerCmd.Args, err, string(out))
	}

	// Build with kaniko
	kanikoImage := GetKanikoImage(config.imageRepo, "Dockerfile_test_git")
	dockerRunFlags := []string{"run", "--net=host"}
	dockerRunFlags = addServiceAccountFlags(dockerRunFlags, config.serviceAccount)
	dockerRunFlags = append(
		dockerRunFlags,
		ExecutorImage,
		"-f", dockerfile,
		"-d", kanikoImage,
		"-c", fmt.Sprintf("git://%s", repo),
		"--context-sub-path", filepath.Join(integrationPath, dockerfilesPath),
	)

	kanikoCmd := exec.Command("docker", dockerRunFlags...)

	out, err = RunCommandWithoutTest(kanikoCmd)
	if err != nil {
		t.Errorf("Failed to build image %s with kaniko command %q: %v %s", dockerImage, kanikoCmd.Args, err, string(out))
	}

	diff := containerDiff(t, daemonPrefix+dockerImage, kanikoImage, "--no-cache")

	expected := fmt.Sprintf(emptyContainerDiff, dockerImage, kanikoImage, dockerImage, kanikoImage)
	checkContainerDiffOutput(t, diff, expected)
}

func TestBuildViaRegistryMirror(t *testing.T) {
	repo := getGitRepo()
	dockerfile := "integration/dockerfiles/Dockerfile_registry_mirror"

	// Build with docker
	dockerImage := GetDockerImage(config.imageRepo, "Dockerfile_registry_mirror")
	dockerCmd := exec.Command("docker",
		append([]string{"build",
			"-t", dockerImage,
			"-f", dockerfile,
			repo})...)
	out, err := RunCommandWithoutTest(dockerCmd)
	if err != nil {
		t.Errorf("Failed to build image %s with docker command %q: %s %s", dockerImage, dockerCmd.Args, err, string(out))
	}

	// Build with kaniko
	kanikoImage := GetKanikoImage(config.imageRepo, "Dockerfile_registry_mirror")
	dockerRunFlags := []string{"run", "--net=host"}
	dockerRunFlags = addServiceAccountFlags(dockerRunFlags, config.serviceAccount)
	dockerRunFlags = append(dockerRunFlags, ExecutorImage,
		"-f", dockerfile,
		"-d", kanikoImage,
		"--registry-mirror", "us-mirror.gcr.io",
		"-c", fmt.Sprintf("git://%s", repo))

	kanikoCmd := exec.Command("docker", dockerRunFlags...)

	out, err = RunCommandWithoutTest(kanikoCmd)
	if err != nil {
		t.Errorf("Failed to build image %s with kaniko command %q: %v %s", dockerImage, kanikoCmd.Args, err, string(out))
	}

	diff := containerDiff(t, daemonPrefix+dockerImage, kanikoImage, "--no-cache")

	expected := fmt.Sprintf(emptyContainerDiff, dockerImage, kanikoImage, dockerImage, kanikoImage)
	checkContainerDiffOutput(t, diff, expected)
}

func TestBuildWithLabels(t *testing.T) {
	repo := getGitRepo()
	dockerfile := "integration/dockerfiles/Dockerfile_test_label"

	testLabel := "mylabel=myvalue"

	// Build with docker
	dockerImage := GetDockerImage(config.imageRepo, "Dockerfile_test_label:mylabel")
	dockerCmd := exec.Command("docker",
		append([]string{"build",
			"-t", dockerImage,
			"-f", dockerfile,
			"--label", testLabel,
			repo})...)
	out, err := RunCommandWithoutTest(dockerCmd)
	if err != nil {
		t.Errorf("Failed to build image %s with docker command %q: %s %s", dockerImage, dockerCmd.Args, err, string(out))
	}

	// Build with kaniko
	kanikoImage := GetKanikoImage(config.imageRepo, "Dockerfile_test_label:mylabel")
	dockerRunFlags := []string{"run", "--net=host"}
	dockerRunFlags = addServiceAccountFlags(dockerRunFlags, config.serviceAccount)
	dockerRunFlags = append(dockerRunFlags, ExecutorImage,
		"-f", dockerfile,
		"-d", kanikoImage,
		"--label", testLabel,
		"-c", fmt.Sprintf("git://%s", repo),
	)

	kanikoCmd := exec.Command("docker", dockerRunFlags...)

	out, err = RunCommandWithoutTest(kanikoCmd)
	if err != nil {
		t.Errorf("Failed to build image %s with kaniko command %q: %v %s", dockerImage, kanikoCmd.Args, err, string(out))
	}

	diff := containerDiff(t, daemonPrefix+dockerImage, kanikoImage, "--no-cache")

	expected := fmt.Sprintf(emptyContainerDiff, dockerImage, kanikoImage, dockerImage, kanikoImage)
	checkContainerDiffOutput(t, diff, expected)
}

func TestLayers(t *testing.T) {
	offset := map[string]int{
		"Dockerfile_test_add":     12,
		"Dockerfile_test_scratch": 3,
	}
	for _, dockerfile := range allDockerfiles {
		t.Run("test_layer_"+dockerfile, func(t *testing.T) {
			dockerfile := dockerfile

			t.Parallel()
			if _, ok := imageBuilder.DockerfilesToIgnore[dockerfile]; ok {
				t.SkipNow()
			}

			buildImage(t, dockerfile, imageBuilder)

			// Pull the kaniko image
			dockerImage := GetDockerImage(config.imageRepo, dockerfile)
			kanikoImage := GetKanikoImage(config.imageRepo, dockerfile)
			pullCmd := exec.Command("docker", "pull", kanikoImage)
			RunCommand(pullCmd, t)
			checkLayers(t, dockerImage, kanikoImage, offset[dockerfile])
		})
	}

	err := logBenchmarks("benchmark_layers")
	if err != nil {
		t.Logf("Failed to create benchmark file: %v", err)
	}
}

func buildImage(t *testing.T, dockerfile string, imageBuilder *DockerFileBuilder) {
	if err := imageBuilder.BuildImage(config, dockerfilesPath, dockerfile); err != nil {
		t.Errorf("Error building image: %s", err)
		t.FailNow()
	}
	return
}

// Build each image with kaniko twice, and then make sure they're exactly the same
func TestCache(t *testing.T) {
	populateVolumeCache()
	for dockerfile := range imageBuilder.TestCacheDockerfiles {
		t.Run("test_cache_"+dockerfile, func(t *testing.T) {
			dockerfile := dockerfile
			t.Parallel()

			cache := filepath.Join(config.imageRepo, "cache", fmt.Sprintf("%v", time.Now().UnixNano()))
			// Build the initial image which will cache layers
			if err := imageBuilder.buildCachedImages(config, cache, dockerfilesPath, 0); err != nil {
				t.Fatalf("error building cached image for the first time: %v", err)
			}
			// Build the second image which should pull from the cache
			if err := imageBuilder.buildCachedImages(config, cache, dockerfilesPath, 1); err != nil {
				t.Fatalf("error building cached image for the first time: %v", err)
			}
			// Make sure both images are the same
			kanikoVersion0 := GetVersionedKanikoImage(config.imageRepo, dockerfile, 0)
			kanikoVersion1 := GetVersionedKanikoImage(config.imageRepo, dockerfile, 1)

			diff := containerDiff(t, kanikoVersion0, kanikoVersion1)

			expected := fmt.Sprintf(emptyContainerDiff, kanikoVersion0, kanikoVersion1, kanikoVersion0, kanikoVersion1)
			checkContainerDiffOutput(t, diff, expected)
		})
	}

	if err := logBenchmarks("benchmark_cache"); err != nil {
		t.Logf("Failed to create benchmark file: %v", err)
	}
}

func TestRelativePaths(t *testing.T) {

	dockerfile := "Dockerfile_relative_copy"

	t.Run("test_relative_"+dockerfile, func(t *testing.T) {
		t.Parallel()

		dockerfile = filepath.Join("./dockerfiles", dockerfile)

		contextPath := "./context"

		err := imageBuilder.buildRelativePathsImage(
			config.imageRepo,
			dockerfile,
			config.serviceAccount,
			contextPath,
		)
		if err != nil {
			t.Fatal(err)
		}

		dockerImage := GetDockerImage(config.imageRepo, "test_relative_"+dockerfile)
		kanikoImage := GetKanikoImage(config.imageRepo, "test_relative_"+dockerfile)

		diff := containerDiff(t, daemonPrefix+dockerImage, kanikoImage, "--no-cache")

		expected := fmt.Sprintf(emptyContainerDiff, dockerImage, kanikoImage, dockerImage, kanikoImage)
		checkContainerDiffOutput(t, diff, expected)
	})
}

type fileDiff struct {
	Name string
	Size int
}

type fileDiffResult struct {
	Adds []fileDiff
	Dels []fileDiff
}

type metaDiffResult struct {
	Adds []string
	Dels []string
}

type diffOutput struct {
	Image1   string
	Image2   string
	DiffType string
	Diff     interface{}
}

func (diff *diffOutput) UnmarshalJSON(data []byte) error {
	type Alias diffOutput
	aux := &struct{ *Alias }{Alias: (*Alias)(diff)}
	var rawJSON json.RawMessage
	aux.Diff = &rawJSON
	err := json.Unmarshal(data, &aux)
	if err != nil {
		return err
	}
	switch diff.DiffType {
	case "File":
		var dst fileDiffResult
		err = json.Unmarshal(rawJSON, &dst)
		diff.Diff = &dst
	case "Metadata":
		var dst metaDiffResult
		err = json.Unmarshal(rawJSON, &dst)
		diff.Diff = &dst
	}
	if err != nil {
		return err
	}
	return err
}

var allowedDiffPaths = []string{"/sys"}

func checkContainerDiffOutput(t *testing.T, diff []byte, expected string) {
	// Let's compare the json objects themselves instead of strings to avoid
	// issues with spaces and indents
	t.Helper()

	diffInt := []diffOutput{}
	expectedInt := []diffOutput{}

	err := json.Unmarshal(diff, &diffInt)
	if err != nil {
		t.Error(err)
	}

	err = json.Unmarshal([]byte(expected), &expectedInt)
	if err != nil {
		t.Error(err)
	}

	// Some differences (whitelisted paths, etc.) are known and expected.
	fdr := diffInt[0].Diff.(*fileDiffResult)
	fdr.Adds = filterFileDiff(fdr.Adds)
	fdr.Dels = filterFileDiff(fdr.Dels)
	// Remove some of the meta diffs that shouldn't be checked
	mdr := diffInt[1].Diff.(*metaDiffResult)
	mdr.Adds = filterMetaDiff(mdr.Adds)
	mdr.Dels = filterMetaDiff(mdr.Dels)

	testutil.CheckErrorAndDeepEqual(t, false, nil, expectedInt, diffInt)
}

func filterMetaDiff(metaDiff []string) []string {
	// TODO remove this once we agree testing shouldn't run on docker 18.xx
	// currently docker 18.xx will build an image with Metadata set
	// ArgsEscaped: true, however Docker 19.xx will build an image and have
	// ArgsEscaped: false
	if config.dockerMajorVersion == 19 {
		return metaDiff
	}
	newDiffs := []string{}
	for _, meta := range metaDiff {
		if !strings.HasPrefix(meta, "ArgsEscaped") {
			newDiffs = append(newDiffs, meta)
		}
	}
	return newDiffs
}

func filterFileDiff(f []fileDiff) []fileDiff {
	var newDiffs []fileDiff
	for _, diff := range f {
		isWhitelisted := false
		for _, p := range allowedDiffPaths {
			if util.HasFilepathPrefix(diff.Name, p, false) {
				isWhitelisted = true
				break
			}
		}
		if !isWhitelisted {
			newDiffs = append(newDiffs, diff)
		}
	}
	return newDiffs
}

func checkLayers(t *testing.T, image1, image2 string, offset int) {
	t.Helper()
	img1, err := getImageDetails(image1)
	if err != nil {
		t.Fatalf("Couldn't get details from image reference for (%s): %s", image1, err)
	}

	img2, err := getImageDetails(image2)
	if err != nil {
		t.Fatalf("Couldn't get details from image reference for (%s): %s", image2, err)
	}

	actualOffset := int(math.Abs(float64(img1.numLayers - img2.numLayers)))
	if actualOffset != offset {
		t.Fatalf("Difference in number of layers in each image is %d but should be %d. Image 1: %s, Image 2: %s", actualOffset, offset, img1, img2)
	}
}

func getImageDetails(image string) (*imageDetails, error) {
	ref, err := name.ParseReference(image, name.WeakValidation)
	if err != nil {
		return nil, fmt.Errorf("Couldn't parse referance to image %s: %s", image, err)
	}
	imgRef, err := daemon.Image(ref)
	if err != nil {
		return nil, fmt.Errorf("Couldn't get reference to image %s from daemon: %s", image, err)
	}
	layers, err := imgRef.Layers()
	if err != nil {
		return nil, fmt.Errorf("Error getting layers for image %s: %s", image, err)
	}
	digest, err := imgRef.Digest()
	if err != nil {
		return nil, fmt.Errorf("Error getting digest for image %s: %s", image, err)
	}
	return &imageDetails{
		name:      image,
		numLayers: len(layers),
		digest:    digest.Hex,
	}, nil
}

func logBenchmarks(benchmark string) error {
	if b, err := strconv.ParseBool(os.Getenv("BENCHMARK")); err == nil && b {
		f, err := os.Create(benchmark)
		if err != nil {
			return err
		}
		f.WriteString(timing.Summary())
		defer f.Close()
	}
	return nil
}

type imageDetails struct {
	name      string
	numLayers int
	digest    string
}

func (i imageDetails) String() string {
	return fmt.Sprintf("Image: [%s] Digest: [%s] Number of Layers: [%d]", i.name, i.digest, i.numLayers)
}

func initIntegrationTestConfig() *integrationTestConfig {
	var c integrationTestConfig
	flag.StringVar(&c.gcsBucket, "bucket", "gs://kaniko-test-bucket", "The gcs bucket argument to uploaded the tar-ed contents of the `integration` dir to.")
	flag.StringVar(&c.imageRepo, "repo", "gcr.io/kaniko-test", "The (docker) image repo to build and push images to during the test. `gcloud` must be authenticated with this repo or serviceAccount must be set.")
	flag.StringVar(&c.serviceAccount, "serviceAccount", "", "The path to the service account push images to GCR and upload/download files to GCS.")
	flag.Parse()

	if len(c.serviceAccount) > 0 {
		absPath, err := filepath.Abs("../" + c.serviceAccount)
		if err != nil {
			log.Fatalf("Error getting absolute path for service account: %s\n", c.serviceAccount)
		}
		if _, err := os.Stat(absPath); os.IsNotExist(err) {
			log.Fatalf("Service account does not exist: %s\n", absPath)
		}
		c.serviceAccount = absPath
		os.Setenv("GOOGLE_APPLICATION_CREDENTIALS", absPath)
	}

	if c.imageRepo == "" {
		log.Fatal("You must provide a image repository")
	}

	if c.isGcrRepository() && c.gcsBucket == "" {
		log.Fatalf("You must provide a gcs bucket when using a Google Container Registry (\"%s\" was provided)", c.imageRepo)
	}
	if !strings.HasSuffix(c.imageRepo, "/") {
		c.imageRepo = c.imageRepo + "/"
	}
	c.dockerMajorVersion = getDockerMajorVersion()
	c.onbuildBaseImage = c.imageRepo + "onbuild-base:latest"
	c.hardlinkBaseImage = c.imageRepo + "hardlink-base:latest"
	return &c
}

func meetsRequirements() bool {
	requiredTools := []string{"container-diff", "gsutil"}
	hasRequirements := true
	for _, tool := range requiredTools {
		_, err := exec.LookPath(tool)
		if err != nil {
			fmt.Printf("You must have %s installed and on your PATH\n", tool)
			hasRequirements = false
		}
	}
	return hasRequirements
}

// containerDiff compares the container images image1 and image2.
func containerDiff(t *testing.T, image1, image2 string, flags ...string) []byte {
	flags = append([]string{"diff"}, flags...)
	flags = append(flags, image1, image2,
		"-q", "--type=file", "--type=metadata", "--json")

	containerdiffCmd := exec.Command("container-diff", flags...)
	diff := RunCommand(containerdiffCmd, t)
	t.Logf("diff = %s", string(diff))

	return diff
}