[docker] Add workdir attribute

The workdir attribute set the initial working directory
when starting the docker container.

Contrary to the WORKDIR directive (see
https://docs.docker.com/reference/builder/#workdir), it only affects
the entry point.

--
MOS_MIGRATED_REVID=104201472

7 files changed, 86 insertions, 7 deletions

diff --git a/tools/build_defs/docker/BUILD b/tools/build_defs/docker/BUILD
index 3d70aa3c43..227ca033a3 100644
--- a/tools/build_defs/docker/BUILD
+++ b/tools/build_defs/docker/BUILD
@@ -21,6 +21,7 @@ TEST_TARGETS = [
     "generated_tarball",
     "with_env",
     "with_double_env",
+    "workdir_with_tar_base",
     "link_with_files_base",
 ]
 
diff --git a/tools/build_defs/docker/README.md b/tools/build_defs/docker/README.md
index 3d93ec45ce..a225f5c259 100644
--- a/tools/build_defs/docker/README.md
+++ b/tools/build_defs/docker/README.md
@@ -181,7 +181,7 @@ docker_build(
 ### `docker_build`
 
 `docker_build(name, base, data_path, directory, files, mode, tars,
-debs, symlinks, entrypoint, cmd, env, ports, volumes)`
+debs, symlinks, entrypoint, cmd, env, ports, volumes, workdir)`
 
 <table>
   <thead>
@@ -322,6 +322,17 @@ debs, symlinks, entrypoint, cmd, env, ports, volumes)`
                of volumes to mount.</a></p>
       </td>
     </tr>
+    <tr>
+      <td><code>workdir</code></td>
+      <td>
+        <code>String, optional</code>
+        <p><a href="https://docs.docker.com/reference/builder/#workdir">Initial
+               working directory when running the docker image.</a></p>
+        <p>Because building the image never happen inside a docker container,
+               this working directory does not affect the other actions (e.g.,
+               adding files).</p>
+      </td>
+    </tr>
   </tbody>
   </tbody>
 </table>
diff --git a/tools/build_defs/docker/build_test.sh b/tools/build_defs/docker/build_test.sh
index 1f1e22651b..4381552f34 100755
--- a/tools/build_defs/docker/build_test.sh
+++ b/tools/build_defs/docker/build_test.sh
@@ -110,6 +110,13 @@ function check_env() {
   check_property Env "notop_${input}" "${@}"
 }
 
+function check_workdir() {
+  input="$1"
+  shift
+  check_property WorkingDir "${input}" "${@}"
+  check_property WorkingDir "notop_${input}" "${@}"
+}
+
 function check_layers_aux() {
   local input=${1}
   shift 1
@@ -212,6 +219,12 @@ function test_files_with_tar_base() {
     "b0fe5685bf89a2c875a93495a4e2b7a3f1fb6f27a9ac5dc2b174e7d74cb6fe27"
 }
 
+function test_workdir_with_tar_base() {
+  check_layers "workdir_with_tar_base" \
+    "8b9e4db9dd4b990ee6d8adc2843ad64702ad9063ae6c22e8ca5f94aa54e71277" \
+    "f24cbe53bd1b78909c6dba0bd47016354f3488b35b85aeee68ecc423062b927e"
+}
+
 function test_tar_with_files_base() {
   check_layers "tar_with_files_base" \
     "240dd12c02aee796394ce18eee3108475f7d544294b17fc90ec54e983601fe1b" \
diff --git a/tools/build_defs/docker/docker.bzl b/tools/build_defs/docker/docker.bzl
index 02c8fcf8d9..1f818b032c 100644
--- a/tools/build_defs/docker/docker.bzl
+++ b/tools/build_defs/docker/docker.bzl
@@ -143,6 +143,8 @@ def _metadata_action(ctx, layer, name, output):
       "--ports=%s" % ",".join(ctx.attr.ports),
       "--volumes=%s" % ",".join(ctx.attr.volumes)
       ]
+  if ctx.attr.workdir:
+    args += ["--workdir=" + ctx.attr.workdir]
   inputs = [layer, rewrite_tool, name]
   base = _get_base_artifact(ctx)
   if base:
@@ -248,6 +250,7 @@ docker_build_ = rule(
         "env": attr.string_dict(),
         "ports": attr.string_list(),  # Skylark doesn't support int_list...
         "volumes": attr.string_list(),
+        "workdir": attr.string(),
         # Implicit dependencies.
         "_build_layer": attr.label(
             default=Label("//tools/build_defs/docker:build_layer"),
@@ -337,10 +340,10 @@ docker_build_ = rule(
 #      # https://docs.docker.com/reference/builder/#volume
 #      volumes=[...],
 #
-#      # TODO(mattmoor): NYI
 #      # https://docs.docker.com/reference/builder/#workdir
 #      # NOTE: the normal directive affects subsequent RUN, CMD,
-#      # ENTRYPOINT, ADD, and COPY
+#      # ENTRYPOINT, ADD, and COPY, but this attribute only affects
+#      # the entry point.
 #      workdir="...",
 #
 #      # https://docs.docker.com/reference/builder/#env
diff --git a/tools/build_defs/docker/rewrite_json.py b/tools/build_defs/docker/rewrite_json.py
index dd7d205bac..fe62a91149 100644
--- a/tools/build_defs/docker/rewrite_json.py
+++ b/tools/build_defs/docker/rewrite_json.py
@@ -50,6 +50,10 @@ gflags.DEFINE_list(
     'volumes', None,
     'Augment the "Volumes" of the previous layer')
 
+gflags.DEFINE_string(
+    'workdir', None,
+    'Set the working directory for the layer')
+
 gflags.DEFINE_list(
     'env', None,
     'Augment the "Env" of the previous layer')
@@ -58,7 +62,8 @@ FLAGS = gflags.FLAGS
 
 _MetadataOptionsT = namedtuple(
     'MetadataOptionsT',
-    ['name', 'parent', 'size', 'entrypoint', 'cmd', 'env', 'ports', 'volumes'])
+    ['name', 'parent', 'size', 'entrypoint', 'cmd', 'env', 'ports', 'volumes',
+     'workdir'])
 
 
 class MetadataOptions(_MetadataOptionsT):
@@ -66,12 +71,12 @@ class MetadataOptions(_MetadataOptionsT):
 
   def __new__(cls, name=None, parent=None, size=None,
               entrypoint=None, cmd=None, env=None,
-              ports=None, volumes=None):
+              ports=None, volumes=None, workdir=None):
     """Constructor."""
     return super(MetadataOptions, cls).__new__(
         cls, name=name, parent=parent, size=size,
         entrypoint=entrypoint, cmd=cmd, env=env,
-        ports=ports, volumes=volumes)
+        ports=ports, volumes=volumes, workdir=workdir)
 
 
 _DOCKER_VERSION = '1.5.0'
@@ -175,6 +180,9 @@ def RewriteMetadata(data, options):
     for p in options.volumes:
       output['config']['Volumes'][p] = {}
 
+  if options.workdir:
+    output['config']['WorkingDir'] = options.workdir
+
   # TODO(mattmoor): comment, created, container_config
 
   # container_config contains information about the container
@@ -263,7 +271,8 @@ def main(unused_argv):
       cmd=FLAGS.command,
       env=FLAGS.env,
       ports=FLAGS.ports,
-      volumes=FLAGS.volumes))
+      volumes=FLAGS.volumes,
+      workdir=FLAGS.workdir))
 
   with open(FLAGS.output, 'w') as fp:
     json.dump(output, fp, sort_keys=True)
diff --git a/tools/build_defs/docker/rewrite_json_test.py b/tools/build_defs/docker/rewrite_json_test.py
index 80400e7e99..3d89d1dbf5 100644
--- a/tools/build_defs/docker/rewrite_json_test.py
+++ b/tools/build_defs/docker/rewrite_json_test.py
@@ -646,5 +646,35 @@ class RewriteJsonTest(unittest.TestCase):
         name=name, parent=parent, volumes=[volume]))
     self.assertEquals(expected, actual)
 
+  def testSetWorkingDir(self):
+    in_data = {
+        'config': {
+            'User': 'bleh',
+            'WorkingDir': '/home/bleh',
+            'Volumes': {
+            }
+        }
+    }
+    name = 'deadbeef'
+    parent = 'blah'
+    workdir = '/some/path'
+    expected = {
+        'id': name,
+        'parent': parent,
+        'config': {
+            'User': 'bleh',
+            'WorkingDir': '/some/path',
+            'Volumes': {
+            }
+        },
+        'docker_version': _DOCKER_VERSION,
+        'architecture': _PROCESSOR_ARCHITECTURE,
+        'os': _OPERATING_SYSTEM,
+    }
+
+    actual = RewriteMetadata(in_data, MetadataOptions(
+        name=name, parent=parent, workdir=workdir))
+    self.assertEquals(expected, actual)
+
 if __name__ == '__main__':
   unittest.main()
diff --git a/tools/build_defs/docker/testdata/BUILD b/tools/build_defs/docker/testdata/BUILD
index 8b1bcd194a..75d36e4073 100644
--- a/tools/build_defs/docker/testdata/BUILD
+++ b/tools/build_defs/docker/testdata/BUILD
@@ -68,6 +68,12 @@ docker_build(
 )
 
 docker_build(
+    name = "workdir_with_tar_base",
+    base = ":tar_base",
+    workdir = "/tmp",
+)
+
+docker_build(
     name = "files_with_tar_base",
     base = ":tar_base",
     files = ["bar"],
@@ -216,6 +222,12 @@ docker_build(
 )
 
 docker_build(
+    name = "notop_workdir_with_tar_base",
+    base = ":notop_tar_base",
+    workdir = "/tmp",
+)
+
+docker_build(
     name = "notop_tar_with_files_base",
     base = ":notop_files_base",
     tars = ["two.tar"],