Allow externally managed swift as glance backend

It is possible to have an accessible swift API that is not managed by
kolla-ansible -- for example, ceph exposes a swift API, and using that
requires setting swift as the glance backend.

So, we should loosen the requirement that using the swift backend for
glance requires swift be enabled in kolla-ansible.

Co-Authored-By: Adam Harwell <flux.adam@gmail.com>

Change-Id: I17076d5412d2b1e1f13bb0badceaca85a5cee108

ansible/roles/glance/defaults/main.yml

@@ -93,7 +93,7 @@ glance_backends:
   - name: cinder
     enabled: "{{ enable_cinder | bool }}"
   - name: "swift"
-    enabled: "{{ enable_swift | bool and glance_backend_swift | bool }}"
+    enabled: "{{ glance_backend_swift | bool }}"
 
 glance_store_backends: "{{ glance_backends|selectattr('enabled', 'equalto', true)|list }}"
 

ansible/roles/glance/templates/glance-api.conf.j2

@@ -45,7 +45,7 @@ flavor = keystone
 default_store = vsphere
 {% elif glance_backend_ceph | bool %}
 default_store = rbd
-{% elif enable_swift | bool and glance_backend_swift | bool %}
+{% elif glance_backend_swift | bool %}
 default_store = swift+http
 {% else %}
 default_store = file
@@ -62,7 +62,7 @@ rbd_store_pool = {{ ceph_glance_pool_name }}
 rbd_store_chunk_size = 8
 {% endif %}
 
-{% if enable_swift | bool and glance_backend_swift | bool %}
+{% if glance_backend_swift | bool %}
 swift_store_container = glance
 swift_store_multiple_containers_seed = 0
 swift_store_multi_tenant = False

releasenotes/notes/allow-external-swift-as-glance-backend-242a6dbf7c830d7a.yaml

+---
+features:
+  - |
+    Allow overriding the variable `glance_backend_swift` to enable the swift
+    backend for glance, without requiring swift to be enabled in kolla-ansible.
+    This allows operators to enable an external swift endpoint as the glance
+    backend.