Ensure that apt cache is up to date before installing packages

Change-Id: I6db566bc0a1e3a9d2ad423389522f1c1c418d07c

defaults/main.yml

@@ -41,6 +41,9 @@ pip_required_pip_packages:
   - ndg-httpsclient # SSL SNI support
   - requests # SSL SNI support
 
+## APT Cache options
+cache_timeout: 600
+
 # Validate Certificates when downloading pip. May be set to "no" when proxy server
 # is intercepting the certificates.
 pip_validate_certs: "yes"

tasks/pre_install.yml

@@ -25,6 +25,23 @@
   when:
     - ansible_pkg_mgr == 'yum'
 
+#TODO(evrardjp): Replace the next 2 tasks by a standard apt with cache
+#when https://github.com/ansible/ansible-modules-core/pull/1517 is merged
+#in 1.9.x or we move to 2.0 (if tested working)
+- name: Check apt last update file
+  stat:
+    path: /var/cache/apt
+  register: apt_cache_stat
+  when:
+    - ansible_pkg_mgr == 'apt'
+
+- name: Update apt if needed
+  apt:
+    update_cache: yes
+  when:
+    - ansible_pkg_mgr == 'apt'
+    - "ansible_date_time.epoch|float - apt_cache_stat.stat.mtime > {{cache_timeout}}"
+
 - name: Install apt packages
   apt:
     pkg: "{{ item }}"