Add new Starlark container load rule new_load.bzl (#929)

* Add new Starlark container load rule

* resolve buildifier error

* add tests for loader

* fix buildifier format error

* revert version on line 377 of WORKSPACE

* fix versioning conflict by changing mal-hashed value

* update repositories bzl to include new loader binary release

* update docs

WORKSPACE

@@ -97,6 +97,16 @@ container_load(
     file = "//testdata:pause.tar",
 )
 
+load(
+    "//container:new_load.bzl",
+    "new_container_load",
+)
+
+new_container_load(
+    name = "new_pause_tar",
+    file = "//testdata:pause.tar",
+)
+
 container_pull(
     name = "alpine_linux_amd64",
     registry = "index.docker.io",

container/new_load.bzl

@@ -0,0 +1,63 @@
+# Copyright 2017 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Rule for loading an image from 'docker save' tarball or the current 
+   container_pull tarball format into OCI intermediate layout.
+
+This extracts the tarball amd creates a filegroup of the untarred objects in OCI layout.
+"""
+
+def _impl(repository_ctx):
+    """Core implementation of new_container_load."""
+
+    # Add an empty top-level BUILD file.
+    repository_ctx.file("BUILD", "")
+
+    repository_ctx.file("image/BUILD", """
+package(default_visibility = ["//visibility:public"])
+
+# TODO(xwinxu): this will be changed to new_container_import once that is implemented later
+# similar to what we have in new_pull.bzl
+
+filegroup(
+    name = "image",
+    srcs = glob(["image/**"]),
+)
+exports_files(glob(["**"]))
+""", executable = False)
+
+    result = repository_ctx.execute([
+        repository_ctx.path(repository_ctx.attr._loader),
+        "-directory",
+        repository_ctx.path("image"),
+        "-tarball",
+        repository_ctx.path(repository_ctx.attr.file),
+    ])
+
+    if result.return_code:
+        fail("Importing from tarball failed (status %s): %s" % (result.return_code, result.stderr))
+
+new_container_load = repository_rule(
+    attrs = {
+        "file": attr.label(
+            allow_single_file = True,
+            mandatory = True,
+        ),
+        "_loader": attr.label(
+            executable = True,
+            default = Label("@loader//file:downloaded"),
+            cfg = "host",
+        ),
+    },
+    implementation = _impl,
+)

repositories/repositories.bzl

@@ -84,6 +84,14 @@ def repositories():
                      CONTAINERREGISTRY_RELEASE + "/importer.par")],
         )
 
+    if "loader" not in excludes:
+        http_file(
+            name = "loader",
+            executable = True,
+            sha256 = "30bbb44eae9651a55d07fb9d39f58936fe3d9817780e1887df07d7beb21ef5ad",
+            urls = [("https://storage.googleapis.com/rules_docker/a08df0ab2a345cd07359bb69672dcf21867e50e5/loader-linux-amd64")],
+        )
+
     if "containerregistry" not in excludes:
         http_archive(
             name = "containerregistry",

tests/docker/BUILD

@@ -430,6 +430,30 @@ file_test(
     file = "@new_distroless_base_both//image:oci-layout",
 )
 
+# To test the new container load binary
+file_test(
+    name = "new_pause_tar_test_index_json",
+    content = """{
+   "schemaVersion": 2,
+   "manifests": [
+      {
+         "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
+         "size": 586,
+         "digest": "sha256:22e0bb47f6dd1938d7c30febe82ac37e99907fd8c76421ab87829ad6a3636bf9"
+      }
+   ]
+}""",
+    file = "@new_pause_tar//image:index.json",
+)
+
+file_test(
+    name = "new_pause_tar_test_oci_layout",
+    content = """{
+    "imageLayoutVersion": "1.0.0"
+}""",
+    file = "@new_pause_tar//image:oci-layout",
+)
+
 create_banana_directory(
     name = "banana_directory",
 )