Add ability to change apt/yum package state

The current method of installing the distribution packages required is
set in the tasks and cannot be changed by a deployer.

Currently the apt task always installs the latest package. This results
in unexpected binary changes when a deployer may simply be trying to
execute a configuration change.

This patch adds the ability for a deployer to change the desired state
so that the results are predictable.

Change-Id: Ib58ccc89b868f42295425527eb1a9dbcbe21839c

defaults/main.yml

@@ -19,6 +19,10 @@ swift_ceilometer_enabled: False
 ## Verbosity Options
 debug: False
 
+# Set the package install state for distribution packages
+# Options are 'present' and 'latest'
+swift_package_state: "latest"
+
 swift_git_repo: https://git.openstack.org/openstack/swift
 swift_git_install_branch: master
 swift_requirements_git_repo: https://git.openstack.org/openstack/requirements

releasenotes/notes/package-state-f2309b07440d0ae8.yaml

@@ -0,0 +1,13 @@
+---
+features:
+  - The os_swift role now supports the ability to configure whether
+    apt/yum tasks install the latest available package, or just ensure
+    that the package is present. The default action is to ensure that
+    the latest package is present. The action taken may be changed to
+    only ensure that the package is present by setting
+    ``swift_package_state`` to ``present``.
+upgrade:
+  - The os_swift role always checks whether the latest package is
+    installed when executed. If a deployer wishes to change the check to
+    only validate the presence of the package, the option
+    ``swift_package_state`` should be set to ``present``.

tasks/install-apt.yml

@@ -33,7 +33,7 @@
 - name: Install apt packages
   apt:
     pkg: "{{ item }}"
-    state: latest
+    state: "{{ swift_package_state }}"
   register: install_packages
   until: install_packages|success
   retries: 5
@@ -41,4 +41,4 @@
   with_items: "{{ swift_apt_packages }}"
   tags:
     - swift-install
-    - swift-apt-packages
+    - swift-apt-packages