Prepend path with bin dir of ansible virtualenv

Tools like ara are now installed within the virtualenv where ansible
is installed. We need to add the bindir of those into the path so
ansible will find them.

Change-Id: Ic8d0cf821222f792e892a765b2dccaa0f35653af

tests/fixtures/config/ara-in-path/git/common-config/playbooks/ara.yaml

@@ -0,0 +1,4 @@
+- hosts: localhost
+  tasks:
+    - name: Run ara
+      shell: ara --help

tests/fixtures/config/ara-in-path/git/common-config/zuul.yaml

@@ -0,0 +1,27 @@
+- pipeline:
+    name: check
+    manager: independent
+    post-review: true
+    trigger:
+      gerrit:
+        - event: patchset-created
+    success:
+      gerrit:
+        Verified: 1
+    failure:
+      gerrit:
+        Verified: -1
+
+- job:
+    name: base
+    parent: null
+
+- job:
+    name: test-ara
+    run: playbooks/ara.yaml
+
+- project:
+    name: org/project
+    check:
+      jobs:
+        - test-ara

tests/fixtures/config/ara-in-path/git/org_project/README

@@ -0,0 +1 @@
+test

tests/fixtures/config/ara-in-path/main.yaml

@@ -0,0 +1,8 @@
+- tenant:
+    name: tenant-one
+    source:
+      gerrit:
+        config-projects:
+          - common-config
+        untrusted-projects:
+          - org/project

tests/unit/test_v3.py

@@ -5719,3 +5719,20 @@ class TestDefaultAnsibleVersion(AnsibleZuulTestCase):
             dict(name='ansible-26', result='SUCCESS', changes='1,1'),
             dict(name='ansible-27', result='SUCCESS', changes='1,1'),
         ], ordered=False)
+
+
+class TestAraInPath(AnsibleZuulTestCase):
+    tenant_config_file = 'config/ara-in-path/main.yaml'
+
+    def test_ara_in_path(self):
+        """
+        Tests that executables like ara are in the path of the virtualenv.
+        """
+
+        A = self.fake_gerrit.addFakeChange('org/project', 'master', 'A')
+        self.fake_gerrit.addEvent(A.getPatchsetCreatedEvent(1))
+        self.waitUntilSettled()
+
+        self.assertHistory([
+            dict(name='test-ara', result='SUCCESS', changes='1,1'),
+        ])

zuul/executor/server.py

@@ -1857,6 +1857,13 @@ class AnsibleJob(object):
         pythonpath = [ansible_dir] + pythonpath
         env_copy['PYTHONPATH'] = os.path.pathsep.join(pythonpath)
 
+        # Prepend PATH with ansible_dir/bin so tools installed into the venv
+        # can be called in local tasks.
+        env_copy['PATH'] = '{}{}{}'.format(
+            os.path.dirname(cmd[0]),
+            os.path.pathsep,
+            env_copy['PATH'])
+
         if playbook.trusted:
             opt_prefix = 'trusted'
         else: