Clean up developer mode logic

Fixes the ability to deploy a venv in cases where:
1) developer_mode is not enabled
2) A cached venv is not downloaded from the repo server

Additional cleanup to the developer_mode venv deployment
logic is implemented by adding a *_venv_download var
which is used to decouple developer_mode from the
cached venv extraction process so that a deployer
can force venv builds in-place (disable cached
venv usage) without enabling developer mode
constraints.

Change-Id: I52f58c358b0fbb5735e98683105fb98385a2abfe

defaults/main.yml

@@ -31,6 +31,9 @@ sahara_bin: "/openstack/venvs/sahara-{{ sahara_venv_tag }}/bin"
 
 sahara_etc_dir: "{{ sahara_bin | dirname }}/etc/sahara"
 
+# venv_download, even when true, will use the fallback method of building the
+# venv from scratch if the venv download fails.
+sahara_venv_download: "{{ not sahara_developer_mode | bool }}"
 sahara_venv_download_url: http://127.0.0.1/venvs/untagged/ubuntu/sahara.tgz
 
 sahara_db_config: /etc/sahara/sahara.conf

tasks/sahara_install.yml

@@ -43,7 +43,7 @@
     dest: "/var/cache/{{ sahara_venv_download_url | basename }}"
     checksum: "sha1:{{ lookup('url', sahara_venv_download_url | replace('tgz', 'checksum')) }}"
   register: sahara_get_venv
-  when: not sahara_developer_mode | bool
+  when: sahara_venv_download | bool
 
 - name: Remove existing venv
   file:
@@ -57,15 +57,14 @@
     state: directory
     mode: "0755"
   register: sahara_venv_dir
+  when: sahara_get_venv | changed
 
 - name: Unarchive pre-built venv
   unarchive:
     src: "/var/cache/{{ sahara_venv_download_url | basename }}"
     dest: "{{ sahara_bin | dirname }}"
     copy: "no"
-  when:
-    - not sahara_developer_mode | bool
-    - sahara_get_venv | changed or sahara_venv_dir | changed
+  when: sahara_get_venv | changed
   notify:
     - Restart sahara services
 
@@ -83,7 +82,7 @@
   until: install_packages|success
   retries: 5
   delay: 2
-  when: sahara_developer_mode | bool
+  when: sahara_get_venv | failed or sahara_get_venv | skipped
   notify:
     - Restart sahara services
 
@@ -93,12 +92,9 @@
     state: "absent"
   when:
     - ansible_pkg_mgr == 'yum'
-    - not sahara_developer_mode | bool
-    - sahara_get_venv | changed or sahara_venv_dir | changed
+    - sahara_get_venv | changed
 
 - name: Update virtualenv path
   command: >
     virtualenv-tools --update-path=auto --reinitialize {{ sahara_bin | dirname }}
-  when:
-    - not sahara_developer_mode | bool
-    - sahara_get_venv | changed or sahara_venv_dir | changed
+  when: sahara_get_venv | changed