Don't download image when it's already there

As image should have been already cached in CI [1], we shouldn't
download it again but just verify the checksum.

NOTE - at the time of this commit download.cirros.com is not working
so the cirros image is also switched to 0.4.0 which is present in
the infra CI image.

[1] https://opendev.org/openstack/openstack-ansible/src/branch/master/tests/roles/bootstrap-host/templates/user_variables.aio.yml.j2#L226

(cherry-picked from commit ad4841f70a)
Change-Id: Ib764c70e483513bec5bd97d4499e67beb4501826

defaults/main.yml

@@ -197,12 +197,12 @@ tempest_pip_packages:
 # format: format to use when uploading to glance (required)
 # name: name to use when uploading to glance - default is to use the downloaded file's name (optional)
 tempest_images:
-  - url: "http://download.cirros-cloud.net/0.3.5/cirros-0.3.5-x86_64-disk.img"
-    checksum: "sha256:e137062a4dfbb4c225971b67781bc52183d14517170e16a3841d16f962ae7470"
+  - url: "http://download.cirros-cloud.net/0.4.0/cirros-0.4.0-x86_64-disk.img"
+    checksum: "sha256:a8dd75ecffd4cdd96072d60c2237b448e0c8b2bc94d57f10fdbc8c481d9005b8"
     format: "qcow2"
     name: "cirros"
-  - url: "http://download.cirros-cloud.net/0.3.5/cirros-0.3.5-x86_64-disk.img"
-    checksum: "sha256:e137062a4dfbb4c225971b67781bc52183d14517170e16a3841d16f962ae7470"
+  - url: "http://download.cirros-cloud.net/0.4.0/cirros-0.4.0-x86_64-disk.img"
+    checksum: "sha256:a8dd75ecffd4cdd96072d60c2237b448e0c8b2bc94d57f10fdbc8c481d9005b8"
     format: "qcow2"
     name: "cirros"
 

tasks/tempest_resources.yml

@@ -40,7 +40,7 @@
     - name: Image(s) download
       get_url:
         url: "{{ item.url }}"
-        dest: "{{ tempest_image_dir }}/"
+        dest: "{{ tempest_image_dir }}/{{ item.url | basename }}"
         checksum: "{{ item.checksum | default(omit) }}"
       with_items: "{{ tempest_images }}"
       when: