Add option to set python interpreter for ansible

This patch adds the option to configure the python interpreter
that is used when deploying machines using the ansible deploy
interface.

Also set the default interpreter for tinyipa image with
ansible deploy interface to /usr/bin/python3 on devstack
and marks ironic-standalone job as voting again.

Change-Id: I8eb58fb00980c9e8946e3b3ef77611a9f5212668
Story: #2005159
Task: #29877

devstack/lib/ironic

@@ -1279,6 +1279,9 @@ function configure_ironic_conductor {
                 # we definitely know the default username to use for TinyIPA image
                 IRONIC_ANSIBLE_SSH_USER='tc'
             fi
+            # (rpittau) most recent tinyipa uses python3 natively so we need to change
+            # the default ansible python interpreter.
+            iniset $IRONIC_CONF_FILE ansible default_python_interpreter /usr/bin/python3
         fi
         iniset $IRONIC_CONF_FILE ansible default_key_file $IRONIC_ANSIBLE_SSH_KEY
         if [[ -n $IRONIC_ANSIBLE_SSH_USER ]]; then

ironic/conf/ansible.py

@@ -134,6 +134,10 @@ opts = [
                       "It may be overridden by per-node "
                       "'ansible_clean_steps_config' option in node's "
                       "'driver_info' field.")),
+    cfg.StrOpt('default_python_interpreter',
+               help=_("Absolute path to the python interpreter on the "
+                      "managed machines. By default, ansible uses "
+                      "/usr/bin/python")),
 ]
 
 

ironic/drivers/modules/ansible/deploy.py

@@ -126,6 +126,9 @@ def _run_playbook(node, name, extra_vars, key, tags=None, notags=None):
     playbook = os.path.join(root, name)
     inventory = os.path.join(root, 'inventory')
     ironic_vars = {'ironic': extra_vars}
+    if CONF.ansible.default_python_interpreter:
+        ironic_vars['ansible_python_interpreter'] = (
+            CONF.ansible.default_python_interpreter)
     args = [CONF.ansible.ansible_playbook_script, playbook,
             '-i', inventory,
             '-e', json.dumps(ironic_vars),

ironic/tests/unit/drivers/modules/ansible/test_deploy.py

@@ -10,6 +10,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import json
+
 from ironic_lib import utils as irlib_utils
 import mock
 from oslo_concurrency import processutils
@@ -162,6 +164,33 @@ class TestAnsibleMethods(AnsibleDeployTestCaseBase):
             '/path/to/playbooks/inventory', '-e', '{"ironic": {"foo": "bar"}}',
             '--private-key=/path/to/key', '-vvvv')
 
+    @mock.patch.object(com_utils, 'execute', return_value=('out', 'err'),
+                       autospec=True)
+    def test__run_playbook_ansible_interpreter_python3(self, execute_mock):
+        self.config(group='ansible', playbooks_path='/path/to/playbooks')
+        self.config(group='ansible', config_file_path='/path/to/config')
+        self.config(group='ansible', verbosity=3)
+        self.config(group='ansible',
+                    default_python_interpreter='/usr/bin/python3')
+        self.config(group='ansible', ansible_extra_args='--timeout=100')
+        extra_vars = {'foo': 'bar'}
+
+        ansible_deploy._run_playbook(self.node, 'deploy',
+                                     extra_vars, '/path/to/key',
+                                     tags=['spam'], notags=['ham'])
+
+        execute_mock.assert_called_once_with(
+            'env', 'ANSIBLE_CONFIG=/path/to/config',
+            'ansible-playbook', '/path/to/playbooks/deploy', '-i',
+            '/path/to/playbooks/inventory', '-e',
+            mock.ANY, '--tags=spam', '--skip-tags=ham',
+            '--private-key=/path/to/key', '-vvv', '--timeout=100')
+
+        all_vars = execute_mock.call_args[0][7]
+        self.assertEqual({"ansible_python_interpreter": "/usr/bin/python3",
+                          "ironic": {"foo": "bar"}},
+                         json.loads(all_vars))
+
     @mock.patch.object(com_utils, 'execute',
                        side_effect=processutils.ProcessExecutionError(
                            description='VIKINGS!'),

releasenotes/notes/add-ansible-python-interpreter-2035e0f23d407aaf.yaml

@@ -0,0 +1,13 @@
+---
+features:
+  - Adds option ``[ansible]default_python_interpreter`` to choose
+    the python interpreter that ansible uses on managed machines.
+    By default, ansible uses ``/usr/bin/python`` as interpreter, making the
+    assumption that that path is always present on remote managed systems.
+    This might not be always the case, for example in custom build
+    images or Python 3 native distributions.
+    With this option the operator has the ability to set the absolute
+    path of the python interpreter on the remote machines, for example
+    ``/usr/bin/python3``.
+    The same interpreter will be used in all operations that use the
+    ansible deploy interface.

zuul.d/project.yaml

@@ -11,10 +11,7 @@
     check:
       jobs:
         - ironic-tox-unit-with-driver-libs
-        # making ironic-standalone non voting until we can run ansible
-        # with python3 interpreter on remote machines
-        - ironic-standalone:
-            voting: false
+        - ironic-standalone
         - ironic-tempest-functional-python2
         - ironic-tempest-functional-python3
         - ironic-grenade-dsvm
@@ -40,9 +37,7 @@
       queue: ironic
       jobs:
         - ironic-tox-unit-with-driver-libs
-        # removing ironic-standalone from gate until we can run ansible
-        # with python3 interpreter on remote machines
-        # - ironic-standalone
+        - ironic-standalone
         - ironic-tempest-functional-python2
         - ironic-tempest-functional-python3
         - ironic-grenade-dsvm