Add snapshotting for CIPD packages and dimensions to DM.

dm/tools/jobsim_client/generate_ensure_graph_data_req.py

 #!/usr/bin/env python
 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """
 This is a dumb script that will:
   * compile jobsim_client (for linux-amd64)
   * upload a simple cipd package containing only jobsim_client with the 'latest'
     ref. The package name is 'infra/experimental/dm/jobsim_client/linux-amd64'.
@@ skipping 83 matching lines @@
                 },
               ]
             }
           }
         }
       },
       'command': command,
     }
   }
 
+  if opts.snapshot_dimension:
+    distParams['scheduling']['snapshot_dimensions'] = opts.snapshot_dimension
+
   params = {
     'a': opts.a,
     'b': opts.b,
   }
 
   desc = {
     'quest': [
       {
         'distributor_config_name': 'swarming',
         'parameters': dumps(params),
@@ skipping 27 matching lines @@
       'platform', 'Options for the target platform of the job.')
   plat_grp.add_argument('--os', choices=('linux',), default='linux',
                         help='The OS to compile/run on.')
   plat_grp.add_argument('--arch', choices=('amd64',), default='amd64',
                         help='The Arch to compile/run on.')
   plat_grp.add_argument('--pool', type=str, default='default',
                         help='The swarming pool to use.')
   plat_grp.add_argument('--pin', action='store_true', default=False,
                         help='Emit the request with a pinned package version'
                         ' instead of "latest".')
+  plat_grp.add_argument(
+    '--snapshot-dimension', action='append', help=(
+      'Pin this dimension on re-executions. This will cause re-executions to '
+      'copy the most-specific value of this dependency from the first '
+      'execution to all subsequent re-executions of the same Attempt. May be '
+      'specified multiple times.'
+    ))
 
   cipd_grp = parser.add_argument_group('cipd', 'cipd packaging options')
   cipd_grp.add_argument('--cipd-service-url', default=None,
                         help='The CIPD service to upload to.')
   cipd_grp.add_argument('--cipd-service-account-json', default=None,
                         help='The CIPD service account JSON file to use.')
   cipd_grp.add_argument('--cipd-name',
                         default='infra/experimental/dm/jobsim_client',
                         help='The CIPD package name prefix to upload to. This '
                         'will be appended with the standard os-arch suffix.')
 
   opts = parser.parse_args()
 
   # Use local path for determinisim.
   pkg_dir = os.path.join(THIS_DIR, 'pkg_dir')
   shutil.rmtree(pkg_dir, ignore_errors=True)
   os.mkdir(pkg_dir)
   try:
     compile_pkg(pkg_dir, opts.os, opts.arch)
     pkg_name, version = upload_pkg(pkg_dir, opts.cipd_name, opts.os, opts.arch)
     print_req(opts, pkg_name, version)
   finally:
     shutil.rmtree(pkg_dir, ignore_errors=True)
 
 
 if __name__ == '__main__':
   main()