Extend pkg_tar rule with stamp_mtime attribute

pkg/.bazelrc

@@ -0,0 +1,2 @@
+# Define workspace status command for stamp_mtime attribute in pkg_tar rule
+test --workspace_status_command=./tests/workspace_status.sh

pkg/archive.py

@@ -123,7 +123,8 @@ def __init__(self,
                compression='',
                root_directory='.',
                default_mtime=None,
-               preserve_tar_mtimes=True):
+               preserve_tar_mtimes=True,
+               workspace_status_file=None):
     """TarFileWriter wraps tarfile.open().
 
     Args:
@@ -155,6 +156,22 @@ def __init__(self,
       self.default_mtime = 0
     elif default_mtime == 'portable':
       self.default_mtime = PORTABLE_MTIME
+    elif workspace_status_file is not None:
+      default_mtime_strip = default_mtime.strip()
+      if not default_mtime_strip.startswith("{") or not default_mtime_strip.endswith("}"):
+        raise self.Error('Workspace status file provided, but mtime does not contain a valid key.')
+      default_mtime_key = default_mtime_strip[1:-1]
+      key_found = False
+      with open(workspace_status_file, 'r') as f:
+        for line in f:
+          key, value = line.strip().split(' ', 1)
+          if key == default_mtime_key:
+            key_found = True
+            self.default_mtime = int(value)
+            break
+      if not key_found:
+        raise self.Error('Key "{}" was not found in workspace status file. '.format(default_mtime_key) +
+                         'Please check if the volatile workspace status file contains this key.')
     else:
       self.default_mtime = int(default_mtime)
 

pkg/build_tar.py

@@ -30,19 +30,21 @@ class DebError(Exception):
     pass
 
   def __init__(self, output, directory, compression, root_directory,
-               default_mtime):
+               default_mtime, workspace_status_file=None):
     self.directory = directory
     self.output = output
     self.compression = compression
     self.root_directory = root_directory
     self.default_mtime = default_mtime
+    self.workspace_status_file = workspace_status_file
 
   def __enter__(self):
     self.tarfile = archive.TarFileWriter(
         self.output,
         self.compression,
         self.root_directory,
-        default_mtime=self.default_mtime)
+        default_mtime=self.default_mtime,
+        workspace_status_file=self.workspace_status_file)
     return self
 
   def __exit__(self, t, v, traceback):
@@ -256,6 +258,9 @@ def main():
            'path/to/file=root.root.')
   parser.add_argument('--root_directory', default='./',
                       help='Default root directory is named "."')
+  parser.add_argument('--workspace_status_file',
+                      help='Workspace status file with volatile keys/values '
+                           'for use with "mtime" containing the corresponding key to use.')
   options = parser.parse_args()
 
   # Parse modes arguments
@@ -298,7 +303,7 @@ def main():
   # Add objects to the tar file
   with TarFile(
       options.output, helpers.GetFlagValue(options.directory),
-      options.compression, options.root_directory, options.mtime) as output:
+      options.compression, options.root_directory, options.mtime, options.workspace_status_file) as output:
 
     def file_attributes(filename):
       if filename.startswith('/'):

pkg/docs/reference.md

@@ -244,6 +244,22 @@ Creates a tar file from a list of inputs.
         </p>
       </td>
     </tr>
+    <tr>
+      <td><code>stamp_mtime</code></td>
+      <td>
+        <code>String, optional</code>
+        <p>
+          Stamp variable from workspace status file.
+          The key's name must not start with <code>STABLE_</code>
+          because only "volatile" keys are read.
+        </p>
+        <p>
+          <code>
+          stamp_mtime = "{STAMP_MTIME}",
+          </code>
+        </p>
+      </td>
+    </tr>
   </tbody>
 </table>
 

pkg/pkg.bzl

@@ -90,12 +90,28 @@ def _pkg_tar_impl(ctx):
         "--owner=" + ctx.attr.owner,
         "--owner_name=" + ctx.attr.ownername,
     ]
+    stamp_inputs = []
     if ctx.attr.mtime != _DEFAULT_MTIME:
         if ctx.attr.portable_mtime:
             fail("You may not set both mtime and portable_mtime")
+        if ctx.attr.stamp_mtime:
+            fail("You may not set both mtime and stamp_mtime")
         args.append("--mtime=%d" % ctx.attr.mtime)
     if ctx.attr.portable_mtime:
+        if ctx.attr.stamp_mtime:
+            fail("You may not set both portable_mtime and stamp_mtime")
         args.append("--mtime=portable")
+    if ctx.attr.stamp_mtime:
+        # Only ctx.version_file for file volatile-status.txt is needed
+        # because change of key/value should not invalid existing build
+        stamp_inputs += [ctx.version_file]
+        stamp_mtime_strip = ctx.attr.stamp_mtime.strip()
+        if not stamp_mtime_strip.startswith("{") or not stamp_mtime_strip.endswith("}"):
+            fail("You set stamp_mtime, but this doesn't contain a valid key variable")
+        # Add mtime with stamped mtime variable
+        args.append("--mtime=%s" % stamp_mtime_strip)
+        # Add volatile-status.txt file as argument
+        args.append("--workspace_status_file=%s" % ctx.version_file.path)
 
     # Add runfiles if requested
     file_inputs = []
@@ -162,7 +178,7 @@ def _pkg_tar_impl(ctx):
     ctx.actions.run(
         mnemonic = "PackageTar",
         progress_message = "Writing: %s" % output_file.path,
-        inputs = file_inputs + ctx.files.deps + files,
+        inputs = file_inputs + ctx.files.deps + files + stamp_inputs,
         executable = ctx.executable.build_tar,
         arguments = ["@" + arg_file.path],
         outputs = [output_file],
@@ -322,6 +338,7 @@ pkg_tar_impl = rule(
         "modes": attr.string_dict(),
         "mtime": attr.int(default = _DEFAULT_MTIME),
         "portable_mtime": attr.bool(default = True),
+        "stamp_mtime": attr.string(),
         "owner": attr.string(default = "0.0"),
         "ownername": attr.string(default = "."),
         "owners": attr.string_dict(),

pkg/tests/BUILD

@@ -400,6 +400,15 @@ pkg_tar(
     portable_mtime = False,
 )
 
+pkg_tar(
+    name = "test-tar-stamp_mtime",
+    srcs = [
+        ":etc/nsswitch.conf",
+    ],
+    portable_mtime = False,
+    stamp_mtime = "{STAMP_MTIME}",
+)
+
 py_test(
     name = "pkg_tar_test",
     size = "medium",
@@ -411,6 +420,7 @@ py_test(
         ":test-tar-empty_files.tar",
         ":test-tar-files_dict.tar",
         ":test-tar-mtime.tar",
+        ":test-tar-stamp_mtime.tar",
         ":test-tar-strip_prefix-dot.tar",
         ":test-tar-strip_prefix-empty.tar",
         ":test-tar-strip_prefix-etc.tar",

pkg/tests/archive_test.py

@@ -271,6 +271,11 @@ def testPreserveTarMtimesFalse(self):
       for output_file in f.tar:
         self.assertEqual(output_file.mtime, 0)
 
+  def testStampMtime(self):
+    with archive.TarFileWriter(self.tempfile, default_mtime="{STAMP_MTIME}",
+                               workspace_status_file="./tests/testdata/test_volatile-status.txt") as f:
+      self.assertEqual(f.default_mtime, 946684741)
+
   def testAddingDirectoriesForFile(self):
     with archive.TarFileWriter(self.tempfile) as f:
       f.add_file("d/f")

pkg/tests/pkg_tar_test.py

@@ -142,6 +142,14 @@ def test_mtime(self):
     ]
     self.assertTarFileContent('test-tar-mtime.tar', content)
 
+  def test_stamp_mtime(self):
+      # Note strange mtime. It is specified in the testdata/workspace_status.sh file.
+      content = [
+          {'name': '.', 'mtime': 946684741},
+          {'name': './nsswitch.conf', 'mtime': 946684741},
+      ]
+      self.assertTarFileContent('test-tar-stamp_mtime.tar', content)
+
   def test_basic(self):
     # Check the set of 'test-tar-basic-*' smoke test.
     content = [

pkg/tests/testdata/test_volatile-status.txt

@@ -0,0 +1 @@
+STAMP_MTIME 946684741

pkg/tests/workspace_status.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+stamp_mtime=946684741  # 1999-12-31, 23:58:01
+cat << EOF
+STAMP_MTIME ${stamp_mtime}
+EOF