4 files changed, 47 insertions, 1 deletions
diff --git a/tools/build_defs/docker/BUILD b/tools/build_defs/docker/BUILD
index 01fe75c3b4..d5d6f7b1f7 100644
--- a/tools/build_defs/docker/BUILD
+++ b/tools/build_defs/docker/BUILD
@@ -36,6 +36,8 @@ TEST_DATA = [
     "//tools/build_defs/docker/testdata:gen_image.tar",
     "//tools/build_defs/docker/testdata:data_path_image.tar",
     "//tools/build_defs/docker/testdata:no_data_path_image.tar",
+    "//tools/build_defs/docker/testdata:absolute_data_path_image.tar",
+    "//tools/build_defs/docker/testdata:root_data_path_image.tar",
     "//tools/build_defs/docker/testdata:dummy_repository.tar",
     "//tools/build_defs/docker/testdata:extras_with_deb.tar",
 ]
diff --git a/tools/build_defs/docker/build_test.sh b/tools/build_defs/docker/build_test.sh
index ec4c00f38c..7aea3fd4f7 100755
--- a/tools/build_defs/docker/build_test.sh
+++ b/tools/build_defs/docker/build_test.sh
@@ -352,9 +352,13 @@ function get_layer_listing() {
 function test_data_path() {
   local no_data_path_sha="451d182e5c71840f00ba9726dc0239db73a21b7e89e79c77f677e3f7c5c23d44"
   local data_path_sha="9a41c9e1709558f7ef06f28f66e9056feafa7e0f83990801e1b27c987278d8e8"
+  local absolute_data_path_sha="f196c42ab4f3eb850d9655b950b824db2c99c01527703ac486a7b48bb2a34f44"
+  local root_data_path_sha="19d7fd26d67bfaeedd6232dcd441f14ee163bc81c56ed565cc20e73311c418b6"
 
   check_layers_aux "no_data_path_image" "${no_data_path_sha}"
   check_layers_aux "data_path_image" "${data_path_sha}"
+  check_layers_aux "absolute_data_path_image" "${absolute_data_path_sha}"
+  check_layers_aux "root_data_path_image" "${root_data_path_sha}"
 
   # Without data_path = "." the file will be inserted as `./test`
   # (since it is the path in the package) and with data_path = "."
@@ -367,6 +371,29 @@ function test_data_path() {
     './
 ./test/
 ./test/test'
+
+  # With an absolute path for data_path, we should strip that prefix
+  # from the files' paths. Since the testdata images are in
+  # //tools/build_defs/docker/testdata and data_path is set to
+  # "/tools/build_defs", we should have `docker` as the top-level
+  # directory.
+  check_eq "$(get_layer_listing "absolute_data_path_image" "${absolute_data_path_sha}")" \
+    './
+./docker/
+./docker/testdata/
+./docker/testdata/test/
+./docker/testdata/test/test'
+
+  # With data_path = "/", we expect the entire path from the repository
+  # root.
+  check_eq "$(get_layer_listing "root_data_path_image" "${root_data_path_sha}")" \
+    "./
+./tools/
+./tools/build_defs/
+./tools/build_defs/docker/
+./tools/build_defs/docker/testdata/
+./tools/build_defs/docker/testdata/test/
+./tools/build_defs/docker/testdata/test/test"
 }
 
 function test_extras_with_deb() {
diff --git a/tools/build_defs/docker/docker.bzl b/tools/build_defs/docker/docker.bzl
index 9b1cc31da9..395f0277d0 100644
--- a/tools/build_defs/docker/docker.bzl
+++ b/tools/build_defs/docker/docker.bzl
@@ -71,7 +71,10 @@ def _compute_data_path(out, data_path):
     # Strip ./ from the beginning if specified.
     # There is no way to handle .// correctly (no function that would make
     # that possible and Skylark is not turing complete) so just consider it
-    # as an absolute path.
+    # as an absolute path. A data_path of / should preserve the entire
+    # path up to the repository root.
+    if data_path == "/":
+      return data_path
     if len(data_path) >= 2 and data_path[0:2] == "./":
       data_path = data_path[2:]
     if not data_path or data_path == ".":  # Relative to current package
diff --git a/tools/build_defs/docker/testdata/BUILD b/tools/build_defs/docker/testdata/BUILD
index 88f248f1b2..c1d1896e50 100644
--- a/tools/build_defs/docker/testdata/BUILD
+++ b/tools/build_defs/docker/testdata/BUILD
@@ -39,6 +39,20 @@ docker_build(
 )
 
 docker_build(
+    name = "absolute_data_path_image",
+    data_path = "/tools/build_defs",
+    files = ["//tools/build_defs/docker/testdata/test:test-data"],
+    mode = "0644",
+)
+
+docker_build(
+    name = "root_data_path_image",
+    data_path = "/",
+    files = ["//tools/build_defs/docker/testdata/test:test-data"],
+    mode = "0644",
+)
+
+docker_build(
     name = "gen_image",
     files = [":gen"],
     mode = "0644",