Lock Firefox version at OS level

playbooks/roles/browsers/defaults/main.yml

 browser_deb_pkgs:
     - dbus-x11
-    - firefox=45.0.2+build1-0ubuntu1
+    - firefox
     - google-chrome-stable
     - libcurl3
     - libgconf2-4
@@ -9,6 +9,9 @@ browser_deb_pkgs:
     - xdg-utils
     - xvfb
 
+# Firefox
+firefox_version: version 45.*
+
 # Chrome and ChromeDriver
 chrome_repo: "deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main"
 chromedriver_version: 2.25

playbooks/roles/browsers/tasks/main.yml

@@ -10,10 +10,19 @@
   apt_repository:
     repo: "{{ chrome_repo }}"
     state: present
+- name: lock Firefox version
+  copy:
+    dest: /etc/apt/preferences.d/firefox-pinned-version
+    content: |
+      Package: firefox
+      Pin: {{ firefox_version }}
+      Pin-Priority: 1001
 
 - name: install system packages
-  apt: pkg={{','.join(browser_deb_pkgs)}}
-       state=present update_cache=yes
+  apt:
+    name: "{{ item }}"
+    update_cache: yes
+  with_items: "{{ browser_deb_pkgs }}"
 
 - name: download ChromeDriver
   get_url: