Generate a pyl file with project details that presubmits can read.

This allows the generate_buildbot_json presubmit check to determine
whether or not it should validate that builders exist without having to
parse or scrape starlark source files.

Bug: 1056428
Change-Id: I9540512275d9c8235e92870670d60a2809b1fcdc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2268118
Auto-Submit: Garrett Beaty <gbeaty@chromium.org>
Reviewed-by: Stephen Martinis <martiniss@chromium.org>
Commit-Queue: Stephen Martinis <martiniss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782623}

infra/config/generated/project.pyl

+# This is a non-LUCI generated file
+# This is consumed by presubmit checks that need to validate the config
+{"validate_source_side_specs_have_builder": True}

infra/config/main.star

@@ -28,6 +28,7 @@ lucicfg.config(
         'luci-notify.cfg',
         'luci-scheduler.cfg',
         'project.cfg',
+        'project.pyl',
         'realms.cfg',
         'tricium-prod.cfg',
     ],

infra/config/project.star

@@ -23,6 +23,23 @@ settings = struct(
 )
 
 
+def _generate_project_pyl(ctx):
+  ctx.output['project.pyl'] = '\n'.join([
+      '# This is a non-LUCI generated file',
+      '# This is consumed by presubmit checks that need to validate the config',
+      repr(dict(
+          # On master, we want to ensure that we don't have source side specs
+          # defined for non-existent builders
+          # On branches, we don't want to re-generate the source side specs as
+          # that would increase branch day toil and complicate cherry-picks
+          validate_source_side_specs_have_builder = settings.is_master,
+      )),
+      '',
+  ])
+
+lucicfg.generator(_generate_project_pyl)
+
+
 def master_only_exec(f):
   if settings.is_master:
     exec(f)

testing/buildbot/generate_buildbot_json.py

@@ -1397,16 +1397,18 @@ class BBJSONGenerator(object):
     # references to configs outside of this directory are added, please change
     # their presubmit to run `generate_buildbot_json.py -c`, so that the tree
     # never ends up in an invalid state.
-    project_star = glob.glob(
-        os.path.join(self.args.infra_config_dir, 'project.star'))
-    if project_star:
-      is_master_pattern = re.compile('is_master\s*=\s*(True|False)')
-      for l in self.read_file(project_star[0]).splitlines():
-        match = is_master_pattern.search(l)
-        if match:
-          if match.group(1) == 'False':
-            return None
-          break
+
+    # Get the generated project.pyl so we can check if we should be enforcing
+    # that the specs are for builders that actually exist
+    # If not, return None to indicate that we won't enforce that builders in
+    # waterfalls.pyl are defined in LUCI
+    project_pyl_path = os.path.join(self.args.infra_config_dir, 'generated',
+                                    'project.pyl')
+    if os.path.exists(project_pyl_path):
+      settings = ast.literal_eval(self.read_file(project_pyl_path))
+      if not settings.get('validate_source_side_specs_have_builder', True):
+        return None
+
     bot_names = set()
     milo_configs = glob.glob(
         os.path.join(self.args.infra_config_dir, 'generated', 'luci-milo*.cfg'))

testing/buildbot/generate_buildbot_json_unittest.py

@@ -55,7 +55,7 @@ class FakeBBGen(generate_buildbot_json.BBJSONGenerator):
                waterfalls,
                test_suites,
                luci_milo_cfg,
-               project_star='is_master = True',
+               project_pyl='{"validate_source_side_specs_have_builder": True}',
                exceptions=EMPTY_PYL_FILE,
                mixins=EMPTY_PYL_FILE,
                gn_isolate_map=EMPTY_PYL_FILE,
@@ -72,11 +72,13 @@ class FakeBBGen(generate_buildbot_json.BBJSONGenerator):
         (pyl_files_dir, 'mixins.pyl'): mixins,
         (pyl_files_dir, 'gn_isolate_map.pyl'): gn_isolate_map,
         (pyl_files_dir, 'variants.pyl'): variants,
-        (infra_config_dir, 'project.star'): project_star,
+        (infra_config_dir, 'generated/project.pyl'): project_pyl,
         (infra_config_dir, 'generated/luci-milo.cfg'): luci_milo_cfg,
         (infra_config_dir, 'generated/luci-milo-dev.cfg'): '',
     }
     for (d, filename), content in files.iteritems():
+      if content is None:
+        continue
       path = os.path.join(d, filename)
       parent = os.path.abspath(os.path.dirname(path))
       if not os.path.exists(parent):
@@ -2896,12 +2898,23 @@ class UnitTest(TestCase):
       fbb.check_input_file_consistency(verbose=True)
     self.assertFalse(fbb.printed_lines)
 
-  def test_nonexistent_bot_does_not_raise_on_branch(self):
+  def test_nonexistent_bot_raises_when_no_project_pyl_exists(self):
     fbb = FakeBBGen(self.args,
                     UNKNOWN_BOT_GTESTS_WATERFALL,
                     FOO_TEST_SUITE,
                     LUCI_MILO_CFG,
-                    project_star='is_master = False')
+                    project_pyl=None)
+    with self.assertRaises(generate_buildbot_json.BBGenErr):
+      fbb.check_input_file_consistency(verbose=True)
+    self.assertFalse(fbb.printed_lines)
+
+  def test_nonexistent_bot_does_not_raise_when_validation_disabled(self):
+    fbb = FakeBBGen(
+        self.args,
+        UNKNOWN_BOT_GTESTS_WATERFALL,
+        FOO_TEST_SUITE,
+        LUCI_MILO_CFG,
+        project_pyl='{"validate_source_side_specs_have_builder": False}')
     fbb.check_input_file_consistency(verbose=True)
 
   def test_waterfalls_must_be_sorted(self):