Re-land "Modify annotated_run to read factory configs from the slave checkout."

scripts/slave/annotated_run.py

Index: scripts/slave/annotated_run.py
diff --git a/scripts/slave/annotated_run.py b/scripts/slave/annotated_run.py
index 136e84bde1fd9c6e37f5af71d4a00c1f94b58d0c..833d9ce499f19b5e10ceea7a7a34839d7c648567 100755
--- a/scripts/slave/annotated_run.py
+++ b/scripts/slave/annotated_run.py
@@ -3,6 +3,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import json
 import optparse
 import os
 import subprocess
@@ -15,44 +16,105 @@ sys.path.append(os.path.join(BUILD_ROOT, 'third_party'))
 
 from common import annotator
 from common import chromium_utils
+from common import master_cfg_utils
 from slave import recipe_universe
 
 from recipe_engine import main as recipe_main
 
 
-def get_recipe_properties(factory_properties, build_properties):
+def get_recipe_properties(factory_properties, build_properties,
+                          master_overrides_slave):
   """Constructs the recipe's properties from buildbot's properties.
 
-  This merges factory_properties and build_properties.  Furthermore, it
-  tries to reconstruct the 'recipe' property from builders.pyl if it isn't
-  already there, and in that case merges in properties form builders.pyl.
+  This retrieves the current factory properties from the master_config
+  in the slave's checkout (the factory properties handed to us from the
+  master might be out of date), and merges in the build properties.
+
+  Using the values from the checkout allows us to do things like change
+  the recipe and other factory properties for a builder without needing
+  a master restart.
   """
-  properties = factory_properties.copy()
-  properties.update(build_properties)
-
-  # Try to reconstruct the recipe from builders.pyl if not given.
-  if 'recipe' not in properties:
-    mastername = properties['mastername']
-    buildername = properties['buildername']
-
-    master_path = chromium_utils.MasterPath(mastername)
-    builders_file = os.path.join(master_path, 'builders.pyl')
-    if os.path.isfile(builders_file):
-      builders = chromium_utils.ReadBuildersFile(builders_file)
-      assert buildername in builders['builders'], (
-        'buildername %s is not listed in %s' % (buildername, builders_file))
-      builder = builders['builders'][buildername]
-
-      # Update properties with builders.pyl data.
-      properties['recipe'] = builder['recipe']
-      properties.update(builder.get('properties', {}))
-    else:
-      raise LookupError('Cannot find recipe for %s on %s' %
-                        (build_properties['buildername'],
-                        build_properties['mastername']))
+  master_properties = factory_properties.copy()
+  master_properties.update(build_properties)
+
+  mastername = master_properties['mastername']
+  buildername = master_properties['buildername']
+  if mastername and buildername:
+    slave_properties = get_factory_properties_from_disk(mastername, buildername)
+  else:
+    slave_properties = {}
+
+  properties = master_properties.copy()
+  conflicting_properties = {}
+  for name in slave_properties:
+    if master_properties.get(name) != slave_properties[name]:
+      conflicting_properties[name] = (master_properties.get(name),
+                                   slave_properties[name])
+
+  if conflicting_properties:
+    print 'The following build properties differ between master and slave:'
+    for name, (master_value, slave_value) in conflicting_properties.items():
+      print ('  "%s": master: "%s", slave: "%s"' % (
+          name,
+          "<unset>" if (master_value is None) else master_value,
+          slave_value))
+    print ("Using the values from the %s." %
+           ("master" if master_overrides_slave else "slave"))
+
+  if not master_overrides_slave:
+    for name, (_, slave_value) in conflicting_properties.items():
+      properties[name] = slave_value
+
   return properties
 
 
+def get_factory_properties_from_disk(mastername, buildername):
+  master_list = master_cfg_utils.GetMasters()
+  master_path = None
+  for name, path in master_list:
+    if name == mastername:
+      master_path = path
+
+  if not master_path:
+    raise LookupError('master "%s" not found.' % mastername)
+
+  script_path = os.path.join(BUILD_ROOT, 'scripts', 'tools',
+                             'dump_master_cfg.py')
+  dump_cmd = [sys.executable,
+              script_path,
+              master_path, '-']
+  proc = subprocess.Popen(dump_cmd, cwd=BUILD_ROOT, stdout=subprocess.PIPE,
+                          stderr=subprocess.PIPE)
+  out, err = proc.communicate()
+  exit_code = proc.returncode
+
+  if exit_code:
+    raise LookupError('Failed to get the master config; dump_master_cfg %s'
+                      'returned %d):\n%s\n%s\n'% (
+                      mastername, exit_code, out, err))
+
+  config = json.loads(out)
+
+  # Now extract just the factory properties for the requested builder
+  # from the master config.
+  props = {}
+  for builder_dict in config['builders']:
+    if builder_dict['name'] == buildername:
+      factory_properties = builder_dict['factory']['properties']
+      for name, (value, _) in factory_properties.items():
+        props[name] = value
+
+  if not props:
+    raise LookupError('builder "%s" not found on in master "%s"' %
+                      (buildername, mastername))
+
+  if 'recipe' not in props:
+    raise LookupError('Cannot find recipe for %s on %s' %
+                      (buildername, mastername))
+
+  return props
+
+
 def get_args(argv):
   """Process command-line arguments."""
 
@@ -76,6 +138,9 @@ def get_args(argv):
                     help='factory properties in b64 gz JSON format')
   parser.add_option('--keep-stdin', action='store_true', default=False,
                     help='don\'t close stdin when running recipe steps')
+  parser.add_option('--master-overrides-slave', action='store_true',
+                    help='use the property values given on the command line '
+                         'from the master, not the ones looked up on the slave')
   return parser.parse_args(argv)
 
 
@@ -113,7 +178,8 @@ def update_scripts():
 def main(argv):
   opts, _ = get_args(argv)
   properties = get_recipe_properties(
-      opts.factory_properties, opts.build_properties)
+      opts.factory_properties, opts.build_properties,
+      opts.master_overrides_slave)
   stream = annotator.StructuredAnnotationStream()
   ret = recipe_main.run_steps(properties, stream,
                               universe=recipe_universe.get_universe())