[changes] Specify cluster too in the config

Summary:
Address kyle's comment re: cluster.

I had verified that cluster is not used for selecting the node and so assumed that we need not pass it. But after the request is sent, jenkins tried to find a machine with the given CLUSTER tag. So we need to pass the right cluster info

Test Plan: unit tests

Reviewers: kylec, vishal

Reviewed By: vishal

Subscribers: wwu

Differential Revision: https://tails.corp.dropbox.com/D84153

changes/backends/jenkins/generic_builder.py

@@ -9,6 +9,7 @@ class JenkinsGenericBuilder(JenkinsBuilder):
     def __init__(self, master_urls=None, *args, **kwargs):
         self.script = kwargs.pop('script')
         self.cluster = kwargs.pop('cluster')
+        self.diff_cluster = kwargs.pop('diff_cluster', None)
         self.path = kwargs.pop('path', '')
         self.workspace = kwargs.pop('workspace', '')
 
@@ -38,12 +39,17 @@ def get_job_parameters(self, job, script=None, target_id=None, path=None):
         else:
             repo_url = repository.url
 
+        cluster = self.cluster
+        is_diff = not job.source.is_commit()
+        if is_diff and self.diff_cluster:
+            cluster = self.diff_cluster
+
         params.extend([
             {'name': 'CHANGES_PID', 'value': project.slug},
             {'name': 'REPO_URL', 'value': repo_url},
             {'name': 'SCRIPT', 'value': script},
             {'name': 'REPO_VCS', 'value': repository.backend.name},
-            {'name': 'CLUSTER', 'value': self.cluster},
+            {'name': 'CLUSTER', 'value': cluster},
             {'name': 'WORK_PATH', 'value': path},
             {'name': 'C_WORKSPACE', 'value': self.workspace},
         ])

tests/changes/backends/jenkins/test_generic_builder.py

@@ -11,6 +11,7 @@ class JenkinsGenericBuilderTest(BaseTestCase):
         'job_name': 'server',
         'script': 'py.test',
         'cluster': 'default',
+        'diff_cluster': 'diff_cluster',
     }
 
     def test_get_job_parameters(self):
@@ -35,3 +36,15 @@ def test_get_job_parameters(self):
         result = builder.get_job_parameters(job)
         assert {'name': 'WORK_PATH', 'value': ''} in result
         assert {'name': 'C_WORKSPACE', 'value': ''} in result
+
+    def test_get_job_parameters_diff(self):
+        project = self.create_project()
+        patch = self.create_patch()
+        source = self.create_source(project, patch=patch)
+        build = self.create_build(project, source=source)
+        job = self.create_job(build)
+
+        builder = self.get_builder()
+
+        result = builder.get_job_parameters(job, path='foo')
+        assert {'name': 'CLUSTER', 'value': self.builder_options['diff_cluster']} in result