Validate virtual environment while running a job/inventory update

Currently we only check the custom virtual environment path when
it's created. However, to tackle with the case when the venv might
have been changed/deleted afterward, we need to validate it at
run-time too.

Signed-off-by: Vismay Golwala <vgolwala@redhat.com>

awx/main/tasks.py

@@ -65,7 +65,7 @@ from awx.main.utils import (get_ssh_version, update_scm_url,
                             ignore_inventory_computed_fields,
                             ignore_inventory_group_removal, extract_ansible_vars, schedule_task_manager,
                             get_awx_version)
-from awx.main.utils.common import _get_ansible_version
+from awx.main.utils.common import _get_ansible_version, get_custom_venv_choices
 from awx.main.utils.safe_yaml import safe_dump, sanitize_jinja
 from awx.main.utils.reload import stop_local_services
 from awx.main.utils.pglock import advisory_lock
@@ -93,6 +93,12 @@ Try upgrading OpenSSH or providing your private key in an different format. \
 logger = logging.getLogger('awx.main.tasks')
 
 
+class InvalidVirtualenvError(Exception):
+
+    def __init__(self, message):
+        self.message = message
+
+
 def dispatch_startup():
     startup_logger = logging.getLogger('awx.main.tasks')
     startup_logger.info("Syncing Schedules")
@@ -892,10 +898,13 @@ class BaseTask(object):
         env['PATH'] = os.path.join(venv_path, "bin") + ":" + env['PATH']
         venv_libdir = os.path.join(venv_path, "lib")
 
-        if not isolated and not os.path.exists(venv_libdir):
+        if not isolated and (
-            raise RuntimeError(
+            not os.path.exists(venv_libdir) or
-                'a valid Python virtualenv does not exist at {}'.format(venv_path)
+            os.path.join(venv_path, '') not in get_custom_venv_choices()
-            )
+        ):
+            raise InvalidVirtualenvError(_(
+                'Invalid virtual environment selected: {}'.format(venv_path)
+            ))
 
         isolated_manager.set_pythonpath(venv_libdir, env)
 
@@ -1252,6 +1261,9 @@ class BaseTask(object):
                 status = 'failed'
                 extra_update_fields['job_explanation'] = self.instance.job_explanation
 
+        except InvalidVirtualenvError as e:
+            extra_update_fields['job_explanation'] = e.message
+            logger.error('{} {}'.format(self.instance.log_format, e.message))
         except Exception:
             # this could catch programming or file system errors
             extra_update_fields['result_traceback'] = traceback.format_exc()

awx/main/tests/unit/test_tasks.py

@@ -525,10 +525,10 @@ class TestGenericRun():
         job.project.custom_virtualenv = '/venv/missing'
         task = tasks.RunJob()
 
-        with pytest.raises(RuntimeError) as e:
+        with pytest.raises(tasks.InvalidVirtualenvError) as e:
             task.build_env(job, private_data_dir)
 
-        assert 'a valid Python virtualenv does not exist at /venv/missing' == str(e.value)
+        assert 'Invalid virtual environment selected: /venv/missing' == str(e.value)
 
 
 class TestAdhocRun(TestJobExecution):