Use updated get_url module checksum functionality

Starting in Ansible 2.0, the get_url [1] module provides the
ability for a checksum to be provided to the get_url module
which will be verified against the local destination file
and the task skipped if it matches.

[1] http://docs.ansible.com/ansible/get_url_module.html

This patch implements the use of this functionality.

The ability to ignore a venv download failure is also removed
as this is not necessary or desirable. It is better for the
download to fail and the playbook execution to stop immediately
so that the failure point is exposed.

Change-Id: I7f0274d332b81b9d597b5f40a428f9a51030bbd4

meta/main.yml

@@ -18,7 +18,7 @@ galaxy_info:
   description: Installation and setup of cinder
   company: Rackspace
   license: Apache2
-  min_ansible_version: 1.9
+  min_ansible_version: 2.0
   platforms:
     - name: Ubuntu
       versions:

tasks/cinder_install.yml

@@ -40,49 +40,19 @@
   retries: 5
   delay: 2
 
-- name: Get local venv checksum
-  stat:
-    path: "/var/cache/{{ cinder_venv_download_url | basename }}"
-    get_md5: False
-  when:
-    - not cinder_developer_mode | bool
-  register: local_venv_stat
-
-- name: Get remote venv checksum
-  uri:
-    url: "{{ cinder_venv_download_url | replace('tgz', 'checksum') }}"
-    return_content: True
-  when:
-    - not cinder_developer_mode | bool
-  register: remote_venv_checksum
-
-# TODO: When project moves to ansible 2 we can pass this a sha256sum which will:
-#       a) allow us to remove force: yes
-#       b) allow the module to calculate the checksum of dest file which would
-#          result in file being downloaded only if provided and dest sha256sum
-#          checksums differ
 - name: Attempt venv download
   get_url:
     url: "{{ cinder_venv_download_url }}"
     dest: "/var/cache/{{ cinder_venv_download_url | basename }}"
-    force: yes
-  failed_when: false
-  register: get_venv
-  when:
-    - not cinder_developer_mode | bool
-    - (local_venv_stat.stat.exists == False or
-        {{ local_venv_stat.stat.checksum is defined and local_venv_stat.stat.checksum != remote_venv_checksum.content | trim }})
-
-- name: Set cinder get_venv fact
-  set_fact:
-    cinder_get_venv: "{{ get_venv }}"
+    checksum: "sha1:{{ lookup('url', cinder_venv_download_url | replace('tgz', 'checksum')) }}"
+  register: cinder_get_venv
+  when: not cinder_developer_mode | bool
 
 - name: Remove existing venv
   file:
     path: "{{ cinder_bin | dirname }}"
     state: absent
-  when:
-    - cinder_get_venv | changed
+  when: cinder_get_venv | changed
 
 - name: Create cinder venv dir
   file:
@@ -117,8 +87,7 @@
   until: install_packages|success
   retries: 5
   delay: 2
-  when:
-    - cinder_get_venv | failed or cinder_developer_mode | bool
+  when: cinder_developer_mode | bool
   notify: Restart cinder services
 
 - name: Update virtualenv path
@@ -126,4 +95,4 @@
     virtualenv-tools --update-path=auto {{ cinder_bin | dirname }}
   when:
     - not cinder_developer_mode | bool
-    - cinder_get_venv | success
+    - cinder_get_venv | changed or cinder_venv_dir | changed