Repository: ansible/ansible

Issue:
openstack inventory plugin can create group with an 'empty name'  when region is not specified in clouds.yml
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##### SUMMARY
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When region_name is not specified the openstack inventory plugin create empty named group because plugin have not any check for an empty value:

https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/inventory/openstack.py#L257

as soon as 'cloud_' group also created:

https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/inventory/openstack.py#L260 

the empty group can lead to unexpected behavior:
https://github.com/ansible/ansible/issues/42040
##### ISSUE TYPE
 - Bug Report

##### COMPONENT NAME
<!--- Insert, BELOW THIS COMMENT, the name of the module, plugin, task or feature.
Do not include extra details here, e.g. "vyos_command" not "the network module vyos_command" or the full path-->
`contrib/inventory/openstack_inventory.py`
##### ANSIBLE VERSION
<!--- Paste, BELOW THIS COMMENT, verbatim output from "ansible --version" between quotes below -->
```
ansible 2.5.5
  config file = /Users/igor.tiunov/Sources/ansible-openstack-bug/ansible.cfg
  configured module search path = [u'/Users/igor.tiunov/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python2.7/site-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 2.7.14 (default, Mar  9 2018, 23:57:12) [GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)]
```

##### CONFIGURATION
<!--- If using Ansible 2.4 or above, paste, BELOW THIS COMMENT, the results of "ansible-config dump --only-changed"
Otherwise, mention any settings you have changed/added/removed in ansible.cfg
(or using the ANSIBLE_* environment variables).-->
```
DEFAULT_HOST_LIST(/Users/igor.tiunov/Sources/ansible-openstack-bug/ansible.cfg) = [u'/Users/igor.tiunov/Sources/ansible-openstack-bug/openstack.yml']
DEFAULT_VAULT_PASSWORD_FILE(env: ANSIBLE_VAULT_PASSWORD_FILE) = /Users/igor.tiunov/tmp/.vault
INVENTORY_ENABLED(/Users/igor.tiunov/Sources/ansible-openstack-bug/ansible.cfg) = ['openstack']
```
##### OS / ENVIRONMENT
<!--- Mention, BELOW THIS COMMENT, the OS you are running Ansible from, and the OS you are
managing, or say "N/A" for anything that is not platform-specific.
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e.g. if this is a network bug the version of firmware on the network device.-->
Max OSX and rhel/windows instances on openstack
##### STEPS TO REPRODUCE
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For new features, show how the feature would be used. -->
1. Create clouds.yaml like this:
https://github.com/ITD27M01/ansible-openstack-bug/blob/master/clouds.yaml
https://docs.openstack.org/os-client-config/latest/user/configuration.html
2. Run ansible-invetnory --list
3. See the empty group in inventory:
https://github.com/ITD27M01/ansible-openstack-bug/blob/master/openstack-inventory.json#L2
https://github.com/ITD27M01/ansible-openstack-bug/blob/master/openstack-inventory.json#L260
<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

<!--- You can also paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- What did you expect to happen when running the steps above? -->
Empty group is not created
##### ACTUAL RESULTS
<!--- What actually happened? If possible run with extra verbosity (-vvvv) -->
Empty group is created
<!--- Paste verbatim command output between quotes below -->
```

```



Discussion:
Files identified in the description:
* [lib/ansible/plugins/inventory/openstack.py](https://github.com/ansible/ansible/blob/devel/lib/ansible/plugins/inventory/openstack.py)

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cc @dagnello @emonty @juliakreger @omgjlk @rcarrillocruz @shrews @thingee
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Files identified in the description:
* [contrib/inventory/openstack_inventory.py](https://github.com/ansible/ansible/blob/devel/contrib/inventory/openstack_inventory.py)

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cc @emonty @gtema 

Resolving patch:
diff --git a/lib/ansible/plugins/inventory/openstack.py b/lib/ansible/plugins/inventory/openstack.py
--- a/lib/ansible/plugins/inventory/openstack.py
+++ b/lib/ansible/plugins/inventory/openstack.py
@@ -253,7 +253,8 @@ def _get_groups_from_server(self, server_vars, namegroup=True):
         groups.append(cloud)
 
         # Create a group on region
-        groups.append(region)
+        if region:
+            groups.append(region)
 
         # And one by cloud_region
         groups.append("%s_%s" % (cloud, region))


Test patch: