dockerfile: add --parents flag for COPY

Co-Authored-By: Dmitrii Efimov <[email protected]>
Signed-off-by: Justin Chadwell <[email protected]>

Signed-off-by: Justin Chadwell <[email protected]>

.golangci.yml

@@ -7,6 +7,7 @@ run:
 
  build-tags:
  - dfrunsecurity
+ - dfparents
 
 linters:
  enable:

frontend/dockerfile/dockerfile2llb/convert.go

@@ -753,6 +753,7 @@ func dispatch(d *dispatchState, cmd command, opt dispatchOpt) error {
  chown: c.Chown,
  chmod: c.Chmod,
  link: c.Link,
+ parents: c.Parents,
  location: c.Location(),
  opt: opt,
  })
@@ -1159,6 +1160,14 @@ func dispatchCopy(d *dispatchState, cfg copyConfig) error {
  AllowEmptyWildcard: true,
  }}, copyOpt...)
 
+ if cfg.parents {
+ path := strings.TrimPrefix(src, "/")
+ opts = append(opts, &llb.CopyInfo{
+ IncludePatterns: []string{path},
+ })
+ src = "/"
+ }
+
  if a == nil {
  a = llb.Copy(cfg.source, src, dest, opts...)
  } else {
@@ -1249,6 +1258,7 @@ type copyConfig struct {
  link bool
  keepGitDir bool
  checksum digest.Digest
+ parents bool
  location []parser.Range
  opt dispatchOpt
 }

frontend/dockerfile/dockerfile_parents_test.go

@@ -0,0 +1,77 @@
+//go:build dfparents
+// +build dfparents
+
+package dockerfile
+
+import (
+ "os"
+ "path/filepath"
+ "testing"
+
+ "github.com/containerd/continuity/fs/fstest"
+ "github.com/moby/buildkit/client"
+ "github.com/moby/buildkit/frontend/dockerui"
+ "github.com/moby/buildkit/util/testutil/integration"
+ "github.com/stretchr/testify/require"
+)
+
+var parentsTests = integration.TestFuncs(
+ testCopyParents,
+)
+
+func init() {
+ allTests = append(allTests, parentsTests...)
+}
+
+func testCopyParents(t *testing.T, sb integration.Sandbox) {
+ f := getFrontend(t, sb)
+
+ dockerfile := []byte(`
+FROM scratch
+COPY --parents foo1/foo2/bar /
+
+WORKDIR /test
+COPY --parents foo1/foo2/ba* .
+`)
+
+ dir, err := integration.Tmpdir(
+ t,
+ fstest.CreateFile("Dockerfile", dockerfile, 0600),
+ fstest.CreateDir("foo1", 0700),
+ fstest.CreateDir("foo1/foo2", 0700),
+ fstest.CreateFile("foo1/foo2/bar", []byte(`testing`), 0600),
+ fstest.CreateFile("foo1/foo2/baz", []byte(`testing2`), 0600),
+ )
+ require.NoError(t, err)
+
+ c, err := client.New(sb.Context(), sb.Address())
+ require.NoError(t, err)
+ defer c.Close()
+
+ destDir := t.TempDir()
+
+ _, err = f.Solve(sb.Context(), c, client.SolveOpt{
+ Exports: []client.ExportEntry{
+ {
+ Type: client.ExporterLocal,
+ OutputDir: destDir,
+ },
+ },
+ LocalDirs: map[string]string{
+ dockerui.DefaultLocalNameDockerfile: dir,
+ dockerui.DefaultLocalNameContext: dir,
+ },
+ }, nil)
+ require.NoError(t, err)
+
+ dt, err := os.ReadFile(filepath.Join(destDir, "foo1/foo2/bar"))
+ require.NoError(t, err)
+ require.Equal(t, "testing", string(dt))
+
+ dt, err = os.ReadFile(filepath.Join(destDir, "test/foo1/foo2/bar"))
+ require.NoError(t, err)
+ require.Equal(t, "testing", string(dt))
+ dt, err = os.ReadFile(filepath.Join(destDir, "test/foo1/foo2/baz"))
+ require.NoError(t, err)
+ require.Equal(t, "testing2", string(dt))
+}

frontend/dockerfile/docs/reference.md

@@ -1559,6 +1559,46 @@ path, using `--link` is always recommended. The performance of `--link` is
 equivalent or better than the default behavior and, it creates much better
 conditions for cache reuse.
 
+
+## COPY --parents
+
+> **Note**
+>
+> Available in [`docker/dockerfile-upstream:master-labs`](#syntax).
+> Will be included in `docker/dockerfile:1.6-labs`.
+
+```dockerfile
+COPY [--parents[=<boolean>]] <src>... <dest>
+```
+
+The `--parents` flag preserves parent directories for `src` entries. This flag defaults to `false`.
+
+```dockerfile
+# syntax=docker/dockerfile-upstream:master-labs
+FROM scratch
+
+COPY ./x/a.txt ./y/a.txt /no_parents/
+COPY --parents ./x/a.txt ./y/a.txt /parents/
+
+# /no_parents/a.txt
+# /parents/x/a.txt
+# /parents/y/a.txt
+```
+
+This behavior is analogous to the [Linux `cp` utility's](https://www.man7.org/linux/man-pages/man1/cp.1.html)
+`--parents` flag.
+
+Note that, without the `--parents` flag specified, any filename collision will
+fail the Linux `cp` operation with an explicit error message
+(`cp: will not overwrite just-created './x/a.txt' with './y/a.txt'`), where the
+Buildkit will silently overwrite the target file at the destination.
+
+While it is possible to preserve the directory structure for `COPY`
+instructions consisting of only one `src` entry, usually it is more beneficial
+to keep the layer count in the resulting image as low as possible. Therefore,
+with the `--parents` flag, the Buildkit is capable of packing multiple
+`COPY` instructions together, keeping the directory structure intact.
+
 ## ENTRYPOINT
 
 ENTRYPOINT has two forms:

frontend/dockerfile/instructions/commands.go

@@ -270,10 +270,11 @@ func (c *AddCommand) Expand(expander SingleWordExpander) error {
 type CopyCommand struct {
  withNameAndCode
  SourcesAndDest
- From string
- Chown string
- Chmod string
- Link bool
+ From string
+ Chown string
+ Chmod string
+ Link bool
+ Parents bool // parents preserves directory structure
 }
 
 func (c *CopyCommand) Expand(expander SingleWordExpander) error {

frontend/dockerfile/instructions/parse.go

@@ -34,6 +34,8 @@ type parseRequest struct {
 var parseRunPreHooks []func(*RunCommand, parseRequest) error
 var parseRunPostHooks []func(*RunCommand, parseRequest) error
 
+var parentsEnabled = false
+
 func nodeArgs(node *parser.Node) []string {
  result := []string{}
  for ; node.Next != nil; node = node.Next {
@@ -315,6 +317,7 @@ func parseCopy(req parseRequest) (*CopyCommand, error) {
  flFrom := req.flags.AddString("from", "")
  flChmod := req.flags.AddString("chmod", "")
  flLink := req.flags.AddBool("link", false)
+ flParents := req.flags.AddBool("parents", false)
  if err := req.flags.Parse(); err != nil {
  return nil, err
  }
@@ -331,6 +334,7 @@ func parseCopy(req parseRequest) (*CopyCommand, error) {
  Chown: flChown.Value,
  Chmod: flChmod.Value,
  Link: flLink.Value == "true",
+ Parents: (flParents.Value == "true") && parentsEnabled, // silently ignore if not -labs
  }, nil
 }
 

frontend/dockerfile/instructions/parse_parents.go

@@ -0,0 +1,8 @@
+//go:build dfparents
+// +build dfparents
+
+package instructions
+
+func init() {
+ parentsEnabled = true
+}

frontend/dockerfile/release/labs/tags

@@ -1 +1 @@
-dfrunsecurity
+dfrunsecurity dfparents