Create zuul.executor.hostname ansible variable

It will be helpful to know which executor ansible-playbook is run
from so pass this info into vars.yaml.

Additionally, update our test_v3 playbook test to also validate our
other executor ansible variables.

Change-Id: I22091c8e764ad519878e5d530e5bc72ffd2a4870
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

tests/fixtures/config/ansible/git/common-config/playbooks/check-vars.yaml

@@ -6,3 +6,10 @@
           - nodepool_az == 'test-az'
           - nodepool_region == 'test-region'
           - nodepool_provider == 'test-provider'
+
+    - name: Assert zuul-executor variables are valid.
+      assert:
+        that:
+          - zuul.executor.hostname is defined
+          - zuul.executor.src_root is defined
+          - zuul.executor.log_root is defined

tests/fixtures/config/ansible/git/common-config/zuul.yaml

@@ -50,7 +50,7 @@
 
 - job:
     parent: python27
-    name: nodepool
+    name: check-vars
     nodes:
       - name: ubuntu-xenial
         image: ubuntu-xenial

tests/fixtures/config/ansible/git/org_project/.zuul.yaml

@@ -8,5 +8,5 @@
       jobs:
         - python27
         - faillocal
-        - nodepool
+        - check-vars
         - timeout

tests/unit/test_v3.py

@@ -266,7 +266,7 @@ class TestAnsible(AnsibleZuulTestCase):
         self.assertEqual(build.result, 'ABORTED')
         build = self.getJobFromHistory('faillocal')
         self.assertEqual(build.result, 'FAILURE')
-        build = self.getJobFromHistory('nodepool')
+        build = self.getJobFromHistory('check-vars')
         self.assertEqual(build.result, 'SUCCESS')
         build = self.getJobFromHistory('python27')
         self.assertEqual(build.result, 'SUCCESS')

zuul/executor/server.py

@@ -819,8 +819,10 @@ class AnsibleJob(object):
 
         with open(self.jobdir.vars, 'w') as vars_yaml:
             zuul_vars = dict(args['vars'])
-            zuul_vars['zuul']['executor'] = dict(src_root=self.jobdir.src_root,
-                                                 log_root=self.jobdir.log_root)
+            zuul_vars['zuul']['executor'] = dict(
+                hostname=self.executor_server.hostname,
+                src_root=self.jobdir.src_root,
+                log_root=self.jobdir.log_root)
             vars_yaml.write(
                 yaml.safe_dump(zuul_vars, default_flow_style=False))
         self.writeAnsibleConfig(self.jobdir.untrusted_config)