Add possibility to prevent Tobiko from creating test resources

It can be done with new env variable TOBIKO_PREVENT_CREATE.

Change-Id: I2f0fe7ee1c2673cc4024b7784441f622a7abb103

doc/source/user/config.rst

@@ -238,6 +238,20 @@ in :ref:`tobiko-conf` file::
     floating_network = public
 
 
+Skipping resources creation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In some cases, for example when Tobiko is run after upgrade of cloud, it may be expected
+that resources used for tests should be already created. Tobiko should not try to create
+resources than and just run tests using what is already created.
+To configure Tobiko to not create test resources, environment variable ``TOBIKO_PREVENT_CREATE``
+can be used::
+
+    export TOBIKO_PREVENT_CREATE=True
+
+If this is set to ``True`` or ``1`` then Tobiko will not try to create resources like VMs,
+networks or routers and just run validation of what is exists in the cloud already.
+
 What's Next
 -----------
 

tobiko/config.py

@@ -251,4 +251,18 @@ def get_int_env(name):
     return None
 
 
+def get_bool_env(name):
+    value = get_env(name)
+    if value:
+        value = str(value).lower()
+        if value in ["true", "1"]:
+            return True
+        elif value in ["false", '0']:
+            return False
+        else:
+            LOG.exception("Environment variable %r is not a boolean: %r",
+                          name, value)
+    return None
+
+
 init_config()

tobiko/openstack/heat/_stack.py

@@ -20,6 +20,7 @@ from heatclient import exc
 from oslo_log import log
 
 import tobiko
+from tobiko import config
 from tobiko.openstack.heat import _client
 from tobiko.openstack.heat import _template
 
@@ -75,10 +76,19 @@ class HeatStackFixture(tobiko.SharedFixture):
         self.parameters = _stack_parameters(
             stack=self, obj=(parameters or self.parameters))
         self.client = client or self.client
+        if config.get_bool_env('TOBIKO_PREVENT_CREATE'):
+            self.retry_create_stack = 0
 
         if wait_interval:
             self.wait_interval = wait_interval
 
+    def _get_retry_value(self, retry):
+        if retry is None:
+            retry = self.retry_create_stack
+            if retry is None:
+                retry = 1
+        return int(retry)
+
     def setup_fixture(self):
         self.setup_template()
         self.setup_client()
@@ -99,7 +109,7 @@ class HeatStackFixture(tobiko.SharedFixture):
     def create_stack(self, retry=None):
         """Creates stack based on passed parameters."""
         created_stack_ids = set()
-        retry = retry or self.retry_create_stack or 1
+        retry = self._get_retry_value(retry)
         while True:
             stack = self.wait_for_stack_status(
                 expected_status={CREATE_COMPLETE, CREATE_FAILED,

tobiko/tests/unit/openstack/heat/test_stack.py

@@ -238,6 +238,11 @@ class HeatStackFixtureTest(openstack.OpenstackTest):
     def test_setup_when_create_conflict(self):
         self.test_setup(create_conflict=True)
 
+    def test_setup_when_prevent_to_create_set(self):
+        with mock.patch.dict('os.environ', {'TOBIKO_PREVENT_CREATE': 'True'}):
+            self.test_setup(stacks=[mock_stack('CREATE_COMPLETE')],
+                            call_create=False)
+
     def test_cleanup(self):
         client = MockClient()
         stack = MyStack(client=client)

tobiko/tests/unit/test_config.py

@@ -16,6 +16,8 @@ from __future__ import absolute_import
 
 import os
 
+import mock
+
 from tobiko.tests import unit
 from tobiko import config
 
@@ -103,3 +105,22 @@ class HttpProxyFixtureTest(unit.TobikoUnitTest):
         self.assertEqual(self.MY_HTTP_PROXY, fixture.http_proxy)
         self.assertEqual({'no_proxy': self.MY_NO_PROXY,
                           'http_proxy': self.MY_HTTP_PROXY}, os.environ)
+
+    def test_get_bool_env(self):
+        env_option = "TEST_OPTION"
+
+        true_values = ['True', 'true', 'TRUE', 'TrUe', '1']
+        false_values = ['False', 'false', 'FALSE', 'FaLsE', '0']
+        invalid_values = [None, 'something else', '']
+
+        for value in true_values:
+            with mock.patch.dict('os.environ', {env_option: value}):
+                self.assertIs(True, config.get_bool_env(env_option))
+
+        for value in false_values:
+            with mock.patch.dict('os.environ', {env_option: value}):
+                self.assertIs(False, config.get_bool_env(env_option))
+
+        for value in invalid_values:
+            with mock.patch.dict('os.environ', {env_option: value}):
+                self.assertIsNone(config.get_bool_env(env_option))