Add a rule for generating passwd files.

docker/BUILD

@@ -40,6 +40,7 @@ TEST_TARGETS = [
     "workdir_with_tar_base",
     "link_with_files_base",
     "build_with_tag",
+    "with_passwd",
 ]
 
 TEST_DATA = [

docker/build_test.sh

@@ -547,6 +547,24 @@ function test_build_with_tag() {
     "[\"gcr.io/build/with:tag\"]"
 }
 
+function test_build_with_passwd() {
+  # We should have a tag in our manifest containing the name
+  # specified via the tag kwarg.
+
+  local layer="621fe329a78d65d90d34d6dc277ccac2249bba4c8228222271418bf6b07c4dec"
+  check_layers "with_passwd" "${layer}"
+
+  check_eq "$(get_layer_listing "with_passwd" "${layer}")" \
+    './
+./etc/
+./etc/passwd'
+
+  local test_data="${TEST_DATA_DIR}/with_passwd.tar"
+  echo $test_data
+  passwd_contents=$(tar xOf "${test_data}" "${layer}/layer.tar" | tar xO "./etc/passwd")
+  check_eq ${passwd_contents} "foobar:x:1234:2345:myusernameinfo:/myhomedir:/myshell"
+}
+
 tests=$(grep "^function test_" "${BASH_SOURCE[0]}" \
           | cut -d' ' -f 2 | cut -d'(' -f 1)
 

docker/contrib/passwd.bzl

@@ -0,0 +1,70 @@
+# 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.
+
+load("@bazel_tools//tools/build_defs/pkg:pkg.bzl", "pkg_tar")
+
+def _impl(ctx):
+  """Core implementation of docker_push."""
+
+  f = "%s:x:%s:%s:%s:%s:%s\n" % (
+      ctx.attr.username,
+      ctx.attr.uid,
+      ctx.attr.gid,
+      ctx.attr.info,
+      ctx.attr.home,
+      ctx.attr.shell
+  )
+  ctx.file_action(
+      output = ctx.outputs.out,
+      content = f,
+      executable=False
+  )
+  build_tar = ctx.executable.build_tar
+  args = [
+      "--output=" + ctx.outputs.tar.path,
+      "--file=%s=/etc/passwd" % ctx.outputs.out.path
+  ]
+  arg_file = ctx.new_file(ctx.attr.name + ".args")
+  ctx.file_action(arg_file, "\n".join(args))
+
+  ctx.action(
+      executable = build_tar,
+      arguments = ["--flagfile=" + arg_file.path],
+      inputs = [ctx.outputs.out, arg_file],
+      outputs = [ctx.outputs.tar],
+      use_default_shell_env = True
+  )
+
+passwd_file = rule(
+    attrs = {
+        "username": attr.string(mandatory = True),
+        "uid": attr.int(default = 1000),
+        "gid": attr.int(default = 1000),
+        "info": attr.string(default = "user"),
+        "home": attr.string(default = "/home"),
+        "shell": attr.string(default = "/bin/bash"),
+        "build_tar": attr.label(
+            default = Label("@bazel_tools//tools/build_defs/pkg:build_tar"),
+            cfg = "host",
+            executable = True,
+            allow_files = True,
+        ),
+    },
+    executable = False,
+    outputs = {
+        "out": "%{name}.passwd",
+        "tar": "%{name}.passwd.tar",
+    },
+    implementation = _impl,
+)

docker/testdata/BUILD

@@ -296,3 +296,20 @@ docker_build_with_tag(
     files = ["foo"],
     tag = "gcr.io/build/with:tag",
 )
+
+load("//docker/contrib:passwd.bzl", "passwd_file")
+
+passwd_file(
+    name = "testpasswd",
+    gid = 2345,
+    home = "/myhomedir",
+    info = "myusernameinfo",
+    shell = "/myshell",
+    uid = 1234,
+    username = "foobar",
+)
+
+docker_build(
+    name = "with_passwd",
+    tars = [":testpasswd.passwd.tar"],
+)