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: I00b107b651776c6dffbffb81afcf9b8dfe028b46

meta/main.yml

@@ -4,7 +4,7 @@ galaxy_info:
   description: Deploy Magnum with OpenStack Ansible
   company: OpenStack
   license: Apache-2.0
-  min_ansible_version: 1.9
+  min_ansible_version: 2.0
   version: 0.1.0
   platforms:
   - name: Ubuntu

tasks/install.yml

@@ -38,49 +38,19 @@
   retries: 5
   delay: 2
 
-- name: Get local venv checksum
-  stat:
-    path: "/var/cache/{{ magnum_venv_download_url | basename }}"
-    get_md5: False
-  when:
-    - not magnum_developer_mode | bool
-  register: local_venv_stat
-
-- name: Get remote venv checksum
-  uri:
-    url: "{{ magnum_venv_download_url | replace('tgz', 'checksum') }}"
-    return_content: True
-  when:
-    - not magnum_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: "{{ magnum_venv_download_url }}"
     dest: "/var/cache/{{ magnum_venv_download_url | basename }}"
-    force: yes
+    checksum: "sha1:{{ lookup('url', magnum_venv_download_url | replace('tgz', 'checksum')) }}"
-  failed_when: false
+  register: magnum_get_venv
-  register: get_venv
+  when: not magnum_developer_mode | bool
-  when:
-    - not magnum_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 magnum get_venv fact
-  set_fact:
-    magnum_get_venv: "{{ get_venv }}"
 
 - name: Remove existing venv
   file:
     path: "{{ magnum_bin | dirname }}"
     state: absent
-  when:
+  when: magnum_get_venv | changed
-    - magnum_get_venv | changed
 
 - name: Create magnum venv dir
   file:
@@ -112,8 +82,7 @@
   until: install_packages|success
   retries: 5
   delay: 2
-  when:
+  when: magnum_developer_mode | bool
-    - magnum_get_venv | failed or magnum_developer_mode | bool
   notify: Restart magnum services
 
 - name: Update virtualenv path
@@ -121,4 +90,4 @@
     virtualenv-tools --update-path=auto {{ magnum_bin | dirname }}
   when:
     - not magnum_developer_mode | bool
-    - magnum_get_venv | success
+    - magnum_get_venv | changed or magnum_venv_dir | changed