Merge "Handle the yaml merge operator"

tests/unit/test_configloader.py

@@ -17,9 +17,10 @@ import fixtures
 import logging
 import textwrap
 
-from zuul.configloader import AuthorizationRuleParser
+from zuul.configloader import AuthorizationRuleParser, safe_load_yaml
 
 from tests.base import ZuulTestCase
+from zuul.model import SourceContext
 
 
 class TenantParserTestCase(ZuulTestCase):
@@ -75,6 +76,41 @@ class TestTenantSimple(TenantParserTestCase):
         self.assertEqual(job[0].variant_description, "")
         self.assertEqual(job[1].variant_description, "stable")
 
+    def test_merge_anchor(self):
+        to_parse = textwrap.dedent(
+            """
+            - job:
+                name: job1
+                vars: &docker_vars
+                  registry: 'registry.example.org'
+
+            - job:
+                name: job2
+                vars:
+                  <<: &buildenv_vars
+                    image_name: foo
+                  <<: *docker_vars
+
+            - job:
+                name: job3
+                vars:
+                  <<: *buildenv_vars
+                  <<: *docker_vars
+            """)
+        tenant = self.scheds.first.sched.abide.tenants.get('tenant-one')
+        project = tenant.config_projects[0]
+        source_context = SourceContext(project, 'master', 'zuul.yaml', True)
+
+        data = safe_load_yaml(to_parse, source_context)
+        self.assertEqual(len(data), 3)
+        job_vars = [i['job']['vars'] for i in data]
+        # Test that merging worked
+        self.assertEqual(job_vars, [
+            {'registry': 'registry.example.org'},
+            {'registry': 'registry.example.org', 'image_name': 'foo'},
+            {'registry': 'registry.example.org', 'image_name': 'foo'},
+        ])
+
 
 class TestTenantOverride(TenantParserTestCase):
     tenant_config_file = 'config/tenant-parser/override.yaml'

zuul/configloader.py

@@ -368,6 +368,11 @@ class ZuulSafeLoader(yaml.SafeLoader):
     def construct_mapping(self, node, deep=False):
         keys = set()
         for k, v in node.value:
+            # The key << needs to be treated special since that will merge
+            # the anchor into the mapping and not create a key on its own.
+            if k.value == '<<':
+                continue
+
             if k.value in keys:
                 mark = ZuulMark(node.start_mark, node.end_mark,
                                 self.zuul_stream)