Reset uid/gid to 0 in build context to fix cache busting issues on ADD/COPY

cli/command/image/build.go

@@ -21,6 +21,7 @@ import (
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/pkg/archive"
+	"github.com/docker/docker/pkg/idtools"
 	"github.com/docker/docker/pkg/jsonmessage"
 	"github.com/docker/docker/pkg/progress"
 	"github.com/docker/docker/pkg/streamformatter"
@@ -243,6 +244,7 @@ func runBuild(dockerCli command.Cli, options buildOptions) error {
 		excludes = build.TrimBuildFilesFromExcludes(excludes, relDockerfile, options.dockerfileFromStdin())
 		buildCtx, err = archive.TarWithOptions(contextDir, &archive.TarOptions{
 			ExcludePatterns: excludes,
+			ChownOpts:       &idtools.IDPair{UID: 0, GID: 0},
 		})
 		if err != nil {
 			return err

cli/command/image/build_test.go

@@ -6,18 +6,57 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"runtime"
 	"sort"
+	"syscall"
 	"testing"
 
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/internal/test"
 	"github.com/docker/docker/api/types"
 	"github.com/docker/docker/pkg/archive"
+	"github.com/gotestyourself/gotestyourself/fs"
+	"github.com/gotestyourself/gotestyourself/skip"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/net/context"
 )
 
+func TestRunBuildResetsUidAndGidInContext(t *testing.T) {
+	skip.IfCondition(t, runtime.GOOS == "windows", "uid and gid not relevant on windows")
+	dest := fs.NewDir(t, "test-build-context-dest")
+	defer dest.Remove()
+
+	fakeImageBuild := func(_ context.Context, context io.Reader, options types.ImageBuildOptions) (types.ImageBuildResponse, error) {
+		assert.NoError(t, archive.Untar(context, dest.Path(), nil))
+
+		body := new(bytes.Buffer)
+		return types.ImageBuildResponse{Body: ioutil.NopCloser(body)}, nil
+	}
+	cli := test.NewFakeCli(&fakeClient{imageBuildFunc: fakeImageBuild})
+
+	dir := fs.NewDir(t, "test-build-context",
+		fs.WithFile("foo", "some content", fs.AsUser(65534, 65534)),
+		fs.WithFile("Dockerfile", `
+			FROM alpine:3.6
+			COPY foo bar /
+		`),
+	)
+	defer dir.Remove()
+
+	options := newBuildOptions()
+	options.context = dir.Path()
+
+	err := runBuild(cli, options)
+	require.NoError(t, err)
+
+	files, err := ioutil.ReadDir(dest.Path())
+	require.NoError(t, err)
+	for _, fileInfo := range files {
+		assert.Equal(t, uint32(0), fileInfo.Sys().(*syscall.Stat_t).Uid)
+		assert.Equal(t, uint32(0), fileInfo.Sys().(*syscall.Stat_t).Gid)
+	}
+}
 func TestRunBuildDockerfileFromStdinWithCompress(t *testing.T) {
 	dest, err := ioutil.TempDir("", "test-build-compress-dest")
 	require.NoError(t, err)

vendor.conf

@@ -20,15 +20,15 @@ github.com/gogo/protobuf v0.4
 github.com/golang/protobuf 7a211bcf3bce0e3f1d74f9894916e6f116ae83b4
 github.com/gorilla/context v1.1
 github.com/gorilla/mux v1.1
-github.com/gotestyourself/gotestyourself v1.1.0
+github.com/gotestyourself/gotestyourself v1.2.0
 github.com/inconshreveable/mousetrap 76626ae9c91c4f2a10f34cad8ce83ea42c93bb75
 github.com/mattn/go-shellwords v1.0.3
 github.com/Microsoft/go-winio v0.4.4
 github.com/miekg/pkcs11 df8ae6ca730422dba20c768ff38ef7d79077a59f
 github.com/mitchellh/mapstructure f3009df150dadf309fdee4a54ed65c124afad715
 github.com/moby/buildkit da2b9dc7dab99e824b2b1067ad7d0523e32dd2d9 https://github.com/dmcgowan/buildkit.git
 github.com/Nvveen/Gotty a8b993ba6abdb0e0c12b0125c603323a71c7790c https://github.com/ijc25/Gotty
-github.com/opencontainers/go-digest 21dfd564fd89c944783d00d069f33e3e7123c448 
+github.com/opencontainers/go-digest 21dfd564fd89c944783d00d069f33e3e7123c448
 github.com/opencontainers/image-spec v1.0.0
 github.com/opencontainers/runc d40db12e72a40109dfcf28539f5ee0930d2f0277
 github.com/pkg/errors 839d9e913e063e28dfd0e6c7b7512793e0a48be9