Default the ARA installation to a virtualenv

Installing ARA and Ansible system-wide by default is a bit invasive.

Let's default to a virtual environment instead. This means making
sure Apache's mod_wsgi deployment can use that virtualenv amongst
other things.

Depends-On: https://review.openstack.org/567280
Change-Id: I4d86e343b745e31e509dbc929d1fd2c2b10a3623

defaults/main.yml

@@ -17,6 +17,11 @@
 #  along with ARA.  If not, see <http://www.gnu.org/licenses/>.
 
 ara:
+  params:
+    # If ARA should be installed inside a virtualenv
+    virtualenv: true
+    # Location where the virtualenv should be installed
+    virtualenv_path: /opt/ara-venv
   config:
     database: "sqlite:////var/lib/ara/ansible.sqlite"
     # Host to listen on for embedded server, apache or nginx

tasks/apache/mod_wsgi.yml

@@ -31,6 +31,8 @@
 
 - name: Get the location of the WSGI script
   command: which ara-wsgi
+  environment:
+    PATH: "{{ path_with_virtualenv | default(omit) }}"
   register: wsgi_location
   changed_when: false
 

tasks/embedded/standalone.yml

@@ -18,6 +18,8 @@
 
 - name: Get the location of ara-manage
   command: which ara-manage
+  environment:
+    PATH: "{{ path_with_virtualenv | default(omit) }}"
   register: ara_manage
   changed_when: false
 

tasks/main.yml

@@ -41,11 +41,26 @@
     name: pip
     state: present
 
+# Need to make sure setuptools is up to date
+- name: Initialize virtualenv with up-to-date setuptools
+  become: true
+  pip:
+    name: setuptools
+    state: latest
+    virtualenv: "{{ ara.params.virtualenv_path }}"
+  when: ara.params.virtualenv | bool
+
 - name: Install ARA with pip
   become: true
   pip:
     name: ara
     state: present
+    virtualenv: "{{ ara.params.virtualenv | bool | ternary(ara.params.virtualenv_path, omit) }}"
+
+- name: Suffix the virtualenv bin directory to PATH
+  set_fact:
+    path_with_virtualenv: "{{ ara.params.virtualenv_path }}/bin:{{ ansible_env.PATH }}"
+  when: ara.params.virtualenv | bool
 
 - name: Create user for ARA
   become: true
@@ -93,8 +108,10 @@
     - restart ara
     - restart nginx
 
-- name: Get ARA installed location
-  shell: python -c "import os,ara; print(os.path.dirname(ara.__file__))"
+- name: Get ARA's installed location
+  command: python -m ara.setup.path
+  environment:
+    PATH: "{{ path_with_virtualenv | default(omit) }}"
   register: ara_location
   changed_when: false
 

templates/apache_mod_wsgi.conf.j2

@@ -5,17 +5,23 @@
     LogLevel warn
     CustomLog {{ apache_log_path }}/ara-access.log combined
 
+    SetEnv ANSIBLE_CONFIG /etc/ara/ara.cfg
+    {% if ara.params.virtualenv -%}
+    SetEnv ARA_WSGI_USE_VIRTUALENV 1
+    SetEnv ARA_WSGI_VIRTUALENV_PATH {{ ara.params.virtualenv_path }}
+
+    WSGIDaemonProcess ara user=ara group=ara processes=1 threads=4 python-home={{ ara.params.virtualenv_path }}
+    {% else -%}
+    WSGIDaemonProcess ara user=ara group=ara processes=1 threads=4
+    {% endif -%}
+    WSGIScriptAlias {{ ara.config.application_root }} {{ wsgi_script }}
+    WSGIProcessGroup ara
+    WSGIApplicationGroup %{GLOBAL}
+
     <Directory "{{ wsgi_script | dirname }}">
         <Files "ara-wsgi">
             Allow from all
             Satisfy Any
         </Files>
     </Directory>
-
-    WSGIDaemonProcess ara user=ara group=ara processes=1 threads=4
-    WSGIScriptAlias {{ ara.config.application_root }} {{ wsgi_script }}
-    WSGIProcessGroup ara
-    WSGIApplicationGroup %{GLOBAL}
-
-    SetEnv ANSIBLE_CONFIG /etc/ara/ara.cfg
 </VirtualHost>

vars/Debian.yml

@@ -24,6 +24,7 @@ required_packages:
   - libxslt-dev
   - python-dev
   - python-setuptools
+  - python-virtualenv
   - debianutils
 
 required_wsgi_packages:

vars/RedHat.yml

@@ -25,6 +25,7 @@ required_packages:
   - openssl-devel
   - python-devel
   - python-setuptools
+  - python-virtualenv
   - redhat-rpm-config
   - which