Don't match branch protection rule patterns locally

Branch protection rules in github are fn patterns which are currently
matched locally in zuul. This is error prone and can lead in edge
cases to wrong matches resulting in wrong enqueue decisions into gate
pipelines. When requesting branch protection rules in github we also
can request the matching refs along with the rules. This is much safer
since we can plain text match them against the change branch.

Change-Id: Ic995d4b2e16a5d741f0209fa9236959d8f4d10b9

requirements.txt

@@ -32,7 +32,6 @@ paho-mqtt
 cherrypy
 ws4py
 routes
-pathspec
 jsonpath-rw
 urllib3!=1.25.4,!=1.25.5  # https://github.com/urllib3/urllib3/pull/1684
 cheroot!=8.1.*,!=8.2.*,!=8.3.0 # https://github.com/cherrypy/cheroot/issues/263

tests/fake_graphql.py

@@ -26,11 +26,28 @@ class FakePageInfo(ObjectType):
         return False
 
 
+class FakeMatchingRef(ObjectType):
+    name = String()
+
+    def resolve_name(parent, info):
+        return parent
+
+
+class FakeMatchingRefs(ObjectType):
+    nodes = List(FakeMatchingRef)
+
+    def resolve_nodes(parent, info):
+        # To simplify tests just return the pattern and a bogus ref that should
+        # not disturb zuul.
+        return [parent.pattern, 'bogus-ref']
+
+
 class FakeBranchProtectionRule(ObjectType):
     pattern = String()
     requiredStatusCheckContexts = List(String)
     requiresApprovingReviews = Boolean()
     requiresCodeOwnerReviews = Boolean()
+    matchingRefs = Field(FakeMatchingRefs, first=Int())
 
     def resolve_pattern(parent, info):
         return parent.pattern
@@ -44,6 +61,9 @@ class FakeBranchProtectionRule(ObjectType):
     def resolve_requiresCodeOwnerReviews(parent, info):
         return parent.require_codeowners_review
 
+    def resolve_matchingRefs(parent, info, first=None):
+        return parent
+
 
 class FakeBranchProtectionRules(ObjectType):
     nodes = List(FakeBranchProtectionRule)

zuul/driver/github/githubconnection.py

@@ -1635,7 +1635,8 @@ class GithubConnection(BaseConnection):
 
         # For performance reasons fetch all needed data for canMerge upfront
         # using a single graphql call.
-        canmerge_data = self.graphql_client.fetch_canmerge(github, change)
+        canmerge_data = self.graphql_client.fetch_canmerge(
+            github, change, zuul_event_id=event)
 
         # If the PR is a draft it cannot be merged.
         if canmerge_data.get('isDraft', False):

zuul/driver/github/graphql/__init__.py

@@ -13,9 +13,10 @@
 # under the License.
 import logging
 
-import pathspec
 from pkg_resources import resource_string
 
+from zuul.lib.logutil import get_annotated_logger
+
 
 def nested_get(d, *keys, default=None):
     temp = d
@@ -70,7 +71,8 @@ class GraphQLClient:
         response = github.session.post(self.url, json=query)
         return response.json()
 
-    def fetch_canmerge(self, github, change):
+    def fetch_canmerge(self, github, change, zuul_event_id=None):
+        log = get_annotated_logger(self.log, zuul_event_id)
         owner, repo = change.project.name.split('/')
 
         data = self._fetch_canmerge(github, owner, repo, change.number,
@@ -81,14 +83,21 @@ class GraphQLClient:
         # Find corresponding rule to our branch
         rules = nested_get(repository, 'branchProtectionRules', 'nodes',
                            default=[])
-        matching_rule = None
+
-        for rule in rules:
+        # Filter branch protection rules for the one matching the change.
-            pattern = pathspec.patterns.GitWildMatchPattern(
+        matching_rules = [
-                rule.get('pattern'))
+            rule for rule in rules
-            match = pathspec.match_files([pattern], [change.branch])
+            for ref in nested_get(rule, 'matchingRefs', 'nodes', default=[])
-            if match:
+            if ref.get('name') == change.branch
-                matching_rule = rule
+        ]
-                break
+        if len(matching_rules) > 1:
+            log.warn('More than one branch protection rules match change %s',
+                     change)
+            return result
+        elif len(matching_rules) == 1:
+            matching_rule = matching_rules[0]
+        else:
+            matching_rule = None
 
         # If there is a matching rule, get required status checks
         if matching_rule:

zuul/driver/github/graphql/canmerge-legacy.graphql

@@ -11,6 +11,11 @@ query canMergeData(
         requiredStatusCheckContexts
         requiresApprovingReviews
         requiresCodeOwnerReviews
+        matchingRefs(first: 100) {
+          nodes {
+            name
+          }
+        }
       }
     }
     pullRequest(number: $pull) {

zuul/driver/github/graphql/canmerge.graphql

@@ -11,6 +11,11 @@ query canMergeData(
         requiredStatusCheckContexts
         requiresApprovingReviews
         requiresCodeOwnerReviews
+        matchingRefs(first: 100) {
+          nodes {
+            name
+          }
+        }
       }
     }
     pullRequest(number: $pull) {