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: Ibe9d3a98e663cb1c1d7ae07aa10c9cee8e6aba3f

meta/main.yml

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

tasks/zaqar_install.yml

@@ -48,47 +48,15 @@
     - zaqar-install
     - zaqar-pip-packages
 
-- name: Get local venv checksum
-  stat:
-    path: "/var/cache/{{ zaqar_venv_download_url | basename }}"
-    get_md5: False
-  when:
-    - not zaqar_developer_mode | bool
-    - not zaqar_local_mode | bool
-  register: local_venv_stat
-  tags:
-    - zaqar-install
-    - zaqar-pip-packages
-
-- name: Get remote venv checksum
-  uri:
-    url: "{{ zaqar_venv_download_url | replace('tgz', 'checksum') }}"
-    return_content: True
-  when:
-    - not zaqar_developer_mode | bool
-    - not zaqar_local_mode | bool
-  register: remote_venv_checksum
-  tags:
-    - zaqar-install
-    - zaqar-pip-packages
-
-# 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: "{{ zaqar_venv_download_url }}"
     dest: "/var/cache/{{ zaqar_venv_download_url | basename }}"
-    force: yes
-  failed_when: false
-  register: get_venv
+    checksum: "sha1:{{ lookup('url', zaqar_venv_download_url | replace('tgz', 'checksum')) }}"
+  register: zaqar_get_venv
   when:
     - not zaqar_developer_mode | bool
     - not zaqar_local_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 }})
   tags:
     - zaqar-install
     - zaqar-pip-packages
@@ -97,16 +65,8 @@
   copy:
     src: "{{ zaqar_venv_localpath }}"
     dest: "/var/cache/"
-  register: get_venv
-  when:
-    - zaqar_local_mode | bool
-  tags:
-    - zaqar-install
-    - zaqar-pip-packages
-
-- name: Set zaqar get_venv fact
-  set_fact:
-    zaqar_get_venv: "{{ get_venv }}"
+  register: zaqar_get_venv
+  when: zaqar_local_mode | bool
   tags:
     - zaqar-install
     - zaqar-pip-packages
@@ -115,8 +75,7 @@
   file:
     path: "{{ zaqar_bin | dirname }}"
     state: absent
-  when:
-    - zaqar_get_venv | changed
+  when: zaqar_get_venv | changed
   tags:
     - zaqar-install
     - zaqar-pip-packages
@@ -158,8 +117,7 @@
   until: install_packages|success
   retries: 5
   delay: 2
-  when:
-    - zaqar_get_venv | failed or zaqar_developer_mode | bool or zaqar_local_mode | bool
+  when: zaqar_developer_mode | bool or zaqar_local_mode | bool
 #  notify:
 #    - Restart zaqar api
   tags:
@@ -171,7 +129,7 @@
     virtualenv-tools --update-path=auto {{ zaqar_bin | dirname }}
   when:
     - not zaqar_developer_mode | bool or zaqar_local_mode | bool
-    - zaqar_get_venv | success
+    - zaqar_get_venv | changed or zaqar_venv_dir | changed
   tags:
     - zaqar-install
     - zaqar-pip-packages