Add git provenance labels

as per docker#1290

Signed-off-by: Christian Dupuis <cd@atomist.com>

build/build.go

@@ -786,6 +786,16 @@ func BuildWithResultHandler(ctx context.Context, drivers []DriverInfo, opt map[s
 
 	eg, ctx := errgroup.WithContext(ctx)
 
+	for _, opt := range opt {
+		gitLabels, err := addGitProvenance(ctx, opt.Inputs.ContextPath, opt.Inputs.DockerfilePath)
+		if err != nil {
+			return nil, err
+		}
+		for n, v := range gitLabels {
+			opt.Labels[n] = v
+		}
+	}
+
 	for k, opt := range opt {
 		multiDriver := len(m[k]) > 1
 		hasMobyDriver := false

build/git.go

@@ -0,0 +1,98 @@
+package build
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+const DockerfileLabel = "com.docker.image.source.entrypoint"
+
+func addGitProvenance(ctx context.Context, contextPath string, dockerfilePath string) (map[string]string, error) {
+	v, ok := os.LookupEnv("BUILDX_GIT_LABELS")
+	if !ok || contextPath == "" {
+		return nil, nil
+	}
+	labels := make(map[string]string, 0)
+
+	// figure out in which directory the git command needs to run in
+	var wd string
+	if filepath.IsAbs(contextPath) {
+		wd = contextPath
+	} else {
+		cwd, _ := os.Getwd()
+		wd, _ = filepath.Abs(filepath.Join(cwd, contextPath))
+	}
+
+	// check if inside git working tree
+	cmd := exec.CommandContext(ctx, "git", "rev-parse", "--is-inside-work-tree")
+	cmd.Dir = wd
+	err := cmd.Run()
+	if err != nil {
+		logrus.Warnf("Unable to determine Git information")
+		return nil, nil
+	}
+
+	// obtain Git sha of current HEAD
+	cmd = exec.CommandContext(ctx, "git", "rev-parse", "HEAD")
+	cmd.Dir = wd
+	out, err := cmd.Output()
+	if err != nil {
+		return nil, errors.Wrap(err, "error obtaining git head")
+	}
+	sha := strings.TrimSpace(string(out))
+
+	// check if the current HEAD is clean
+	cmd = exec.CommandContext(ctx, "git", "status", "--porcelain", "--ignored")
+	cmd.Dir = wd
+	out, err = cmd.Output()
+	if err != nil {
+		return nil, errors.Wrap(err, "error obtaining git status")
+	}
+	if len(strings.TrimSpace(string(out))) != 0 {
+		sha += "-dirty"
+	}
+	labels[ocispecs.AnnotationRevision] = sha
+
+	// add a remote url if full Git details are requested; if there aren't any remotes don't fail
+	if v == "full" {
+		cmd = exec.CommandContext(ctx, "git", "ls-remote", "--get-url")
+		cmd.Dir = wd
+		out, _ := cmd.Output()
+		if len(out) > 0 {
+			labels[ocispecs.AnnotationSource] = strings.TrimSpace(string(out))
+		}
+	}
+
+	// add Dockerfile path; there is no org.opencontainers annotation for this
+	if dockerfilePath == "" {
+		dockerfilePath = "Dockerfile"
+	}
+
+	// obtain Git root directory
+	cmd = exec.CommandContext(ctx, "git", "rev-parse", "--show-toplevel")
+	cmd.Dir = wd
+	out, err = cmd.Output()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to get git root")
+	}
+	root := strings.TrimSpace(string(out))
+
+	// record only Dockerfile paths that are within the Git root
+	if !filepath.IsAbs(dockerfilePath) {
+		cwd, _ := os.Getwd()
+		dockerfilePath = filepath.Join(cwd, dockerfilePath)
+	}
+	dockerfilePath, _ = filepath.Rel(root, dockerfilePath)
+	if !strings.HasPrefix(dockerfilePath, "..") {
+		labels[DockerfileLabel] = dockerfilePath
+	}
+
+	return labels, nil
+}

build/git_test.go

@@ -0,0 +1,103 @@
+package build
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
+	ocispecs "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/stretchr/testify/assert"
+)
+
+var repoDir string
+
+func setupTest(tb testing.TB) func(tb testing.TB) {
+	repoDir = tb.TempDir()
+	// required for local testing on mac to avoid strange /private symlinks
+	if runtime.GOOS == "darwin" {
+		repoDir, _ = filepath.EvalSymlinks(repoDir)
+	}
+	cmd := exec.Command("git", "init")
+	cmd.Dir = repoDir
+	err := cmd.Run()
+	assert.Nilf(tb, err, "failed to init git repo: %v", err)
+
+	df := []byte("FROM alpine:latest\n")
+	err = os.WriteFile(filepath.Join(repoDir, "Dockerfile"), df, 0644)
+	assert.Nilf(tb, err, "failed to write file: %v", err)
+
+	cmd = exec.Command("git", "add", "Dockerfile")
+	cmd.Dir = repoDir
+	err = cmd.Run()
+	assert.Nilf(tb, err, "failed to add file: %v", err)
+
+	cmd = exec.Command("git", "config", "user.name", "buildx")
+	cmd.Dir = repoDir
+	err = cmd.Run()
+	assert.Nilf(tb, err, "failed to set git user.name: %v", err)
+
+	cmd = exec.Command("git", "config", "user.email", "buildx@docker.com")
+	cmd.Dir = repoDir
+	err = cmd.Run()
+	assert.Nilf(tb, err, "failed to set git user.email: %v", err)
+
+	cmd = exec.Command("git", "commit", "-m", "Initial commit")
+	cmd.Dir = repoDir
+	err = cmd.Run()
+	assert.Nilf(tb, err, "failed to commit: %v", err)
+
+	return func(tb testing.TB) {
+		os.Unsetenv("BUILDX_GIT_LABELS")
+		os.RemoveAll(repoDir)
+	}
+}
+
+func TestAddGitProvenanceDataWithoutEnv(t *testing.T) {
+	defer setupTest(t)(t)
+	labels, err := addGitProvenance(context.Background(), repoDir, filepath.Join(repoDir, "Dockerfile"))
+	assert.Nilf(t, err, "No error expected")
+	assert.Nilf(t, labels, "No labels expected")
+}
+
+func TestAddGitProvenanceDataWithoutLabels(t *testing.T) {
+	defer setupTest(t)(t)
+	os.Setenv("BUILDX_GIT_LABELS", "full")
+	labels, err := addGitProvenance(context.Background(), repoDir, filepath.Join(repoDir, "Dockerfile"))
+	assert.Nilf(t, err, "No error expected")
+	assert.Equal(t, 2, len(labels), "Exactly 2 git provenance labels expected")
+	assert.Equal(t, "Dockerfile", labels[DockerfileLabel], "Expected a dockerfile path provenance label")
+
+	cmd := exec.Command("git", "rev-parse", "HEAD")
+	cmd.Dir = repoDir
+	out, _ := cmd.Output()
+	assert.Equal(t, strings.TrimSpace(string(out)), labels[ocispecs.AnnotationRevision], "Expected a sha provenance label")
+}
+
+func TestAddGitProvenanceDataWithLabels(t *testing.T) {
+	defer setupTest(t)(t)
+	// make a change to test dirty flag
+	df := []byte("FROM alpine:edge\n")
+	os.Mkdir(filepath.Join(repoDir, "dir"), 0755)
+	os.WriteFile(filepath.Join(repoDir, "dir", "Dockerfile"), df, 0644)
+	// add a remote
+	cmd := exec.Command("git", "remote", "add", "origin", "git@github.com:docker/buildx.git")
+	cmd.Dir = repoDir
+	cmd.Run()
+
+	os.Setenv("BUILDX_GIT_LABELS", "full")
+	labels, err := addGitProvenance(context.Background(), repoDir, filepath.Join(repoDir, "Dockerfile"))
+	assert.Nilf(t, err, "No error expected")
+	assert.Equal(t, 3, len(labels), "Exactly 3 git provenance labels expected")
+	assert.Equal(t, "Dockerfile", labels[DockerfileLabel], "Expected a dockerfile path provenance label")
+	assert.Equal(t, "git@github.com:docker/buildx.git", labels[ocispecs.AnnotationSource], "Expected a remote provenance label")
+
+	cmd = exec.Command("git", "rev-parse", "HEAD")
+	cmd.Dir = repoDir
+	out, _ := cmd.Output()
+	assert.Equal(t, fmt.Sprintf("%s-dirty", strings.TrimSpace(string(out))), labels[ocispecs.AnnotationRevision], "Expected a sha provenance label")
+}