bake: fix remote named context subdir handling

Fix using CopyDirContentsOnly when projecting remote named contexts so
subdir contexts keep the same root semantics as local bake runs.

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

bake/bake.go

@@ -1299,6 +1299,7 @@ func updateContext(t *build.Inputs, inp *Input) {
 	for k, v := range t.NamedContexts {
 		if v.Path == "." {
 			t.NamedContexts[k] = build.NamedContext{Path: inp.URL}
+			continue
 		}
 		if strings.HasPrefix(v.Path, "cwd://") || strings.HasPrefix(v.Path, "target:") || strings.HasPrefix(v.Path, "docker-image:") {
 			continue
@@ -1306,7 +1307,9 @@ func updateContext(t *build.Inputs, inp *Input) {
 		if urlutil.IsRemoteURL(v.Path) {
 			continue
 		}
-		st := llb.Scratch().File(llb.Copy(*inp.State, v.Path, "/"), llb.WithCustomNamef("set context %s to %s", k, v.Path))
+		st := llb.Scratch().File(llb.Copy(*inp.State, v.Path, "/", &llb.CopyInfo{
+			CopyDirContentsOnly: true,
+		}), llb.WithCustomNamef("set context %s to %s", k, v.Path))
 		t.NamedContexts[k] = build.NamedContext{State: &st, Path: inp.URL}
 	}
 

tests/bake.go

@@ -51,6 +51,8 @@ var bakeTests = []func(t *testing.T, sb integration.Sandbox){
 	testBakeLocalCwdOverride,
 	testBakeRemoteCmdContextOverride,
 	testBakeRemoteContextSubdir,
+	testBakeRemoteNamedContextSubdir,
+	testBakeRemoteNamedContextDot,
 	testBakeRemoteCmdContextEscapeRoot,
 	testBakeRemoteCmdContextEscapeRelative,
 	testBakeRemoteDockerfileCwd,
@@ -920,6 +922,80 @@ COPY super-cool.txt /
 	require.FileExists(t, filepath.Join(dirDest, "super-cool.txt"))
 }
 
+// https://github.com/docker/buildx/issues/3670
+func testBakeRemoteNamedContextSubdir(t *testing.T, sb integration.Sandbox) {
+	bakefile := []byte(`
+target default {
+	context = "./build"
+	dockerfile = "Dockerfile"
+	contexts = {
+		files = "./files-src/"
+	}
+}
+`)
+	dockerfile := []byte(`
+FROM scratch
+COPY --from=files file.txt /file.txt
+`)
+
+	dir := tmpdir(
+		t,
+		fstest.CreateFile("docker-bake.hcl", bakefile, 0600),
+		fstest.CreateDir("build", 0700),
+		fstest.CreateFile("build/Dockerfile", dockerfile, 0600),
+		fstest.CreateDir("files-src", 0700),
+		fstest.CreateFile("files-src/file.txt", []byte("hello"), 0600),
+	)
+	dirDest := t.TempDir()
+
+	git, err := gitutil.New(gitutil.WithWorkingDir(dir))
+	require.NoError(t, err)
+	gittestutil.GitInit(git, t)
+	gittestutil.GitAdd(git, t, "docker-bake.hcl", "build", "files-src")
+	gittestutil.GitCommit(git, t, "initial commit")
+	addr := gittestutil.GitServeHTTP(git, t)
+
+	out, err := bakeCmd(sb, withDir("/tmp"), withArgs(addr, "--set", "*.output=type=local,dest="+dirDest))
+	require.NoError(t, err, out)
+	require.FileExists(t, filepath.Join(dirDest, "file.txt"))
+}
+
+func testBakeRemoteNamedContextDot(t *testing.T, sb integration.Sandbox) {
+	bakefile := []byte(`
+target default {
+	context = "./build"
+	dockerfile = "Dockerfile"
+	contexts = {
+		files = "."
+	}
+}
+`)
+	dockerfile := []byte(`
+FROM scratch
+COPY --from=files marker.txt /marker.txt
+`)
+
+	dir := tmpdir(
+		t,
+		fstest.CreateFile("docker-bake.hcl", bakefile, 0600),
+		fstest.CreateDir("build", 0700),
+		fstest.CreateFile("build/Dockerfile", dockerfile, 0600),
+		fstest.CreateFile("marker.txt", []byte("hello"), 0600),
+	)
+	dirDest := t.TempDir()
+
+	git, err := gitutil.New(gitutil.WithWorkingDir(dir))
+	require.NoError(t, err)
+	gittestutil.GitInit(git, t)
+	gittestutil.GitAdd(git, t, "docker-bake.hcl", "build", "marker.txt")
+	gittestutil.GitCommit(git, t, "initial commit")
+	addr := gittestutil.GitServeHTTP(git, t)
+
+	out, err := bakeCmd(sb, withDir("/tmp"), withArgs(addr, "--set", "*.output=type=local,dest="+dirDest))
+	require.NoError(t, err, out)
+	require.FileExists(t, filepath.Join(dirDest, "marker.txt"))
+}
+
 func testBakeRemoteCmdContextEscapeRoot(t *testing.T, sb integration.Sandbox) {
 	dirSrc := tmpdir(
 		t,