build: lookup the right git binary on WSL

build/git.go

@@ -48,9 +48,14 @@ func getGitAttributes(ctx context.Context, contextPath string, dockerfilePath st
 		wd, _ = filepath.Abs(filepath.Join(cwd, contextPath))
 	}
 
-	gitc := gitutil.New(gitutil.WithContext(ctx), gitutil.WithWorkingDir(wd))
+	gitc, err := gitutil.New(gitutil.WithContext(ctx), gitutil.WithWorkingDir(wd))
+	if err != nil {
+		logrus.Warnf("Failed to initialize git: %v", err)
+		return
+	}
+
 	if !gitc.IsInsideWorkTree() {
-		logrus.Warnf("Unable to determine Git information")
+		logrus.Warnf("Unable to determine git information")
 		return
 	}
 

build/git_test.go

@@ -12,17 +12,20 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func setupTest(tb testing.TB) {
+func setupTest(tb testing.TB) *gitutil.Git {
+	c, err := gitutil.New()
+	assert.NoError(tb, err)
 	gitutil.Mktmp(tb)
-	gitutil.GitInit(tb)
+	gitutil.GitInit(c, tb)
 	df := []byte("FROM alpine:latest\n")
 	assert.NoError(tb, os.WriteFile("Dockerfile", df, 0644))
-	gitutil.GitAdd(tb, "Dockerfile")
-	gitutil.GitCommit(tb, "initial commit")
+	gitutil.GitAdd(c, tb, "Dockerfile")
+	gitutil.GitCommit(c, tb, "initial commit")
+	return c
 }
 
 func TestGetGitAttributesNoContext(t *testing.T) {
-	setupTest(t)
+	_ = setupTest(t)
 
 	gitattrs := getGitAttributes(context.Background(), "", "Dockerfile")
 	assert.Empty(t, gitattrs)
@@ -80,7 +83,7 @@ func TestGetGitAttributes(t *testing.T) {
 	for _, tt := range cases {
 		tt := tt
 		t.Run(tt.name, func(t *testing.T) {
-			setupTest(t)
+			_ = setupTest(t)
 			if tt.envGitLabels != "" {
 				t.Setenv("BUILDX_GIT_LABELS", tt.envGitLabels)
 			}
@@ -100,8 +103,8 @@ func TestGetGitAttributes(t *testing.T) {
 }
 
 func TestGetGitAttributesWithRemote(t *testing.T) {
-	setupTest(t)
-	gitutil.GitSetRemote(t, "git@github.com:docker/buildx.git")
+	c := setupTest(t)
+	gitutil.GitSetRemote(c, t, "git@github.com:docker/buildx.git")
 
 	t.Setenv("BUILDX_GIT_LABELS", "true")
 	gitattrs := getGitAttributes(context.Background(), ".", "Dockerfile")
@@ -119,7 +122,7 @@ func TestGetGitAttributesWithRemote(t *testing.T) {
 }
 
 func TestGetGitAttributesDirty(t *testing.T) {
-	setupTest(t)
+	_ = setupTest(t)
 
 	// make a change to test dirty flag
 	df := []byte("FROM alpine:edge\n")

go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/hashicorp/go-cty-funcs v0.0.0-20200930094925-2721b1e36840
 	github.com/hashicorp/hcl/v2 v2.8.2
 	github.com/moby/buildkit v0.11.0-rc1.0.20221213193744-862b22d7e7cf
+	github.com/moby/sys/mountinfo v0.6.2
 	github.com/morikuni/aec v1.0.0
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.0.3-0.20220303224323-02efb9a75ee1

go.sum

@@ -411,6 +411,7 @@ github.com/moby/spdystream v0.2.0 h1:cjW1zVyyoiM0T7b6UoySUFqzXMoqRckQtXwGPiBhOM8
 github.com/moby/spdystream v0.2.0/go.mod h1:f7i0iNDQJ059oMTcWxx8MA/zKFIuD/lY+0GqbN2Wy8c=
 github.com/moby/sys/mountinfo v0.5.0/go.mod h1:3bMD3Rg+zkqx8MRYPi7Pyb0Ie97QEBmdxbhnCLlSvSU=
 github.com/moby/sys/mountinfo v0.6.2 h1:BzJjoreD5BMFNmD9Rus6gdd1pLuecOFPt8wC+Vygl78=
+github.com/moby/sys/mountinfo v0.6.2/go.mod h1:IJb6JQeOklcdMU9F5xQ8ZALD+CUr5VlGpwtX+VE0rpI=
 github.com/moby/sys/sequential v0.5.0 h1:OPvI35Lzn9K04PBbCLW0g4LcFAJgHsvXsRyewg5lXtc=
 github.com/moby/sys/sequential v0.5.0/go.mod h1:tH2cOOs5V9MlPiXcQzRC+eEyab644PWKGRYaaV5ZZlo=
 github.com/moby/sys/signal v0.7.0 h1:25RW3d5TnQEoKvRbEKUGay6DCQ46IxAVTT9CUMgmsSI=
@@ -780,6 +781,7 @@ golang.org/x/sys v0.0.0-20211025201205-69cdffdb9359/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20211116061358-0a5406a5449c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211216021012-1d35b9e2eb4e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220114195835-da31bd327af9/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.3.0 h1:w8ZOecv6NaNa/zC8944JTU3vz4u6Lagfk4RPQxv92NQ=
 golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

util/gitutil/gitpath_unix.go

@@ -0,0 +1,42 @@
+//go:build !windows
+// +build !windows
+
+package gitutil
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/moby/sys/mountinfo"
+)
+
+func gitPath(wd string) (string, error) {
+	// On WSL2 we need to check if the current working directory is mounted on
+	// a Windows drive and if so, we need to use the Windows git executable.
+	if os.Getenv("WSL_DISTRO_NAME") != "" && wd != "" {
+		// ensure any symlinks are resolved
+		wdPath, err := filepath.EvalSymlinks(wd)
+		if err != nil {
+			return "", err
+		}
+		mi, err := mountinfo.GetMounts(mountinfo.ParentsFilter(wdPath))
+		if err != nil {
+			return "", err
+		}
+		// find the longest mount point
+		var idx, maxlen int
+		for i := range mi {
+			if len(mi[i].Mountpoint) > maxlen {
+				maxlen = len(mi[i].Mountpoint)
+				idx = i
+			}
+		}
+		if mi[idx].FSType == "9p" {
+			if p, err := exec.LookPath("git.exe"); err == nil {
+				return p, nil
+			}
+		}
+	}
+	return exec.LookPath("git")
+}

util/gitutil/gitpath_windows.go

@@ -0,0 +1,9 @@
+package gitutil
+
+import (
+	"os/exec"
+)
+
+func gitPath(wd string) (string, error) {
+	return exec.LookPath("git.exe")
+}

util/gitutil/gitutil.go

@@ -11,8 +11,9 @@ import (
 
 // Git represents an active git object
 type Git struct {
-	ctx context.Context
-	wd  string
+	ctx     context.Context
+	wd      string
+	gitpath string
 }
 
 // Option provides a variadic option for configuring the git client.
@@ -33,14 +34,22 @@ func WithWorkingDir(wd string) Option {
 }
 
 // New initializes a new git client
-func New(opts ...Option) *Git {
+func New(opts ...Option) (*Git, error) {
+	var err error
 	c := &Git{
 		ctx: context.Background(),
 	}
+
 	for _, opt := range opts {
 		opt(c)
 	}
-	return c
+
+	c.gitpath, err = gitPath(c.wd)
+	if err != nil {
+		return nil, errors.New("git not found in PATH")
+	}
+
+	return c, nil
 }
 
 func (c *Git) IsInsideWorkTree() bool {
@@ -89,16 +98,12 @@ func (c *Git) Tag() (string, error) {
 }
 
 func (c *Git) run(args ...string) (string, error) {
-	if _, err := exec.LookPath("git"); err != nil {
-		return "", errors.New("git not present in PATH")
-	}
-
 	var extraArgs = []string{
 		"-c", "log.showSignature=false",
 	}
 
 	args = append(extraArgs, args...)
-	cmd := exec.Command("git", args...)
+	cmd := exec.CommandContext(c.ctx, c.gitpath, args...)
 	if c.wd != "" {
 		cmd.Dir = c.wd
 	}

util/gitutil/gitutil_test.go

@@ -3,11 +3,14 @@ package gitutil
 import (
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
 func TestGit(t *testing.T) {
-	c := New()
+	c, err := New()
+	assert.NoError(t, err)
+
 	out, err := c.run("status")
 	require.NoError(t, err)
 	require.NotEmpty(t, out)
@@ -19,50 +22,58 @@ func TestGit(t *testing.T) {
 }
 
 func TestGitFullCommit(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+
 	Mktmp(t)
-	GitInit(t)
-	GitCommit(t, "bar")
+	GitInit(c, t)
+	GitCommit(c, t, "bar")
 
-	c := New()
 	out, err := c.FullCommit()
 	require.NoError(t, err)
 	require.Equal(t, 40, len(out))
 }
 
 func TestGitShortCommit(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+
 	Mktmp(t)
-	GitInit(t)
-	GitCommit(t, "bar")
+	GitInit(c, t)
+	GitCommit(c, t, "bar")
 
-	c := New()
 	out, err := c.ShortCommit()
 	require.NoError(t, err)
 	require.Equal(t, 7, len(out))
 }
 
 func TestGitTagsPointsAt(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+
 	Mktmp(t)
-	GitInit(t)
-	GitCommit(t, "bar")
-	GitTag(t, "v0.8.0")
-	GitCommit(t, "foo")
-	GitTag(t, "v0.9.0")
+	GitInit(c, t)
+	GitCommit(c, t, "bar")
+	GitTag(c, t, "v0.8.0")
+	GitCommit(c, t, "foo")
+	GitTag(c, t, "v0.9.0")
 
-	c := New()
 	out, err := c.clean(c.run("tag", "--points-at", "HEAD", "--sort", "-version:creatordate"))
 	require.NoError(t, err)
 	require.Equal(t, "v0.9.0", out)
 }
 
 func TestGitDescribeTags(t *testing.T) {
+	c, err := New()
+	assert.NoError(t, err)
+
 	Mktmp(t)
-	GitInit(t)
-	GitCommit(t, "bar")
-	GitTag(t, "v0.8.0")
-	GitCommit(t, "foo")
-	GitTag(t, "v0.9.0")
+	GitInit(c, t)
+	GitCommit(c, t, "bar")
+	GitTag(c, t, "v0.8.0")
+	GitCommit(c, t, "foo")
+	GitTag(c, t, "v0.9.0")
 
-	c := New()
 	out, err := c.clean(c.run("describe", "--tags", "--abbrev=0"))
 	require.NoError(t, err)
 	require.Equal(t, "v0.9.0", out)

util/gitutil/testutil.go

@@ -7,46 +7,46 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func GitInit(tb testing.TB) {
+func GitInit(c *Git, tb testing.TB) {
 	tb.Helper()
-	out, err := fakeGit("init")
+	out, err := fakeGit(c, "init")
 	require.NoError(tb, err)
 	require.Contains(tb, out, "Initialized empty Git repository")
 	require.NoError(tb, err)
-	GitCheckoutBranch(tb, "main")
-	_, _ = fakeGit("branch", "-D", "master")
+	GitCheckoutBranch(c, tb, "main")
+	_, _ = fakeGit(c, "branch", "-D", "master")
 }
 
-func GitCommit(tb testing.TB, msg string) {
+func GitCommit(c *Git, tb testing.TB, msg string) {
 	tb.Helper()
-	out, err := fakeGit("commit", "--allow-empty", "-m", msg)
+	out, err := fakeGit(c, "commit", "--allow-empty", "-m", msg)
 	require.NoError(tb, err)
 	require.Contains(tb, out, "main", msg)
 }
 
-func GitTag(tb testing.TB, tag string) {
+func GitTag(c *Git, tb testing.TB, tag string) {
 	tb.Helper()
-	out, err := fakeGit("tag", tag)
+	out, err := fakeGit(c, "tag", tag)
 	require.NoError(tb, err)
 	require.Empty(tb, out)
 }
 
-func GitCheckoutBranch(tb testing.TB, name string) {
+func GitCheckoutBranch(c *Git, tb testing.TB, name string) {
 	tb.Helper()
-	out, err := fakeGit("checkout", "-b", name)
+	out, err := fakeGit(c, "checkout", "-b", name)
 	require.NoError(tb, err)
 	require.Empty(tb, out)
 }
 
-func GitAdd(tb testing.TB, file string) {
+func GitAdd(c *Git, tb testing.TB, file string) {
 	tb.Helper()
-	_, err := fakeGit("add", file)
+	_, err := fakeGit(c, "add", file)
 	require.NoError(tb, err)
 }
 
-func GitSetRemote(tb testing.TB, url string) {
+func GitSetRemote(c *Git, tb testing.TB, url string) {
 	tb.Helper()
-	_, err := fakeGit("remote", "add", "origin", url)
+	_, err := fakeGit(c, "remote", "add", "origin", url)
 	require.NoError(tb, err)
 }
 
@@ -62,7 +62,7 @@ func Mktmp(tb testing.TB) string {
 	return folder
 }
 
-func fakeGit(args ...string) (string, error) {
+func fakeGit(c *Git, args ...string) (string, error) {
 	allArgs := []string{
 		"-c", "user.name=buildx",
 		"-c", "user.email=buildx@docker.com",
@@ -71,6 +71,5 @@ func fakeGit(args ...string) (string, error) {
 		"-c", "log.showSignature=false",
 	}
 	allArgs = append(allArgs, args...)
-	c := New()
 	return c.clean(c.run(allArgs...))
 }