From 2449ccb64076cf2b273ed0c3116c43be58b8c61e Mon Sep 17 00:00:00 2001
From: Serge van Ginderachter <serge@vanginderachter.be>
Date: Sat, 23 May 2015 13:31:56 +0200
Subject: [PATCH] Avoid keeping re-downloading container caches

When the cache tarball gets deleted at the end the task set in
playbooks/roles/lxc_hosts/tasks/lxc_cache.yml
then it will be downloaded again at subsequent runs, which makes the
download task not idempotent, and needlessly slow.

The unarchive task also needs to only be executed if the download task
performed a change.

Ensure that the location the download is placed and the directory it's extracted
to are different.

Change-Id: I4e433e82499f5cfa0b5dde44a6aa7bab113d9e0e
---
 playbooks/roles/lxc_hosts/tasks/lxc_cache.yml | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/playbooks/roles/lxc_hosts/tasks/lxc_cache.yml b/playbooks/roles/lxc_hosts/tasks/lxc_cache.yml
index 798400446a..164d1ce6de 100644
--- a/playbooks/roles/lxc_hosts/tasks/lxc_cache.yml
+++ b/playbooks/roles/lxc_hosts/tasks/lxc_cache.yml
@@ -16,8 +16,9 @@
 - name: Download lxc cache(s)
   get_url:
     url: "{{ item.url }}"
-    dest: "/var/cache/lxc/{{ item.name }}"
+    dest: "/var/cache/lxc_{{ item.name }}"
     mode: "0644"
+    force: no
   register: cache_download
   until: cache_download|success
   with_items: lxc_container_caches
@@ -27,19 +28,12 @@
 
 - name: Move lxc cached image into place
   unarchive:
-    src: "/var/cache/lxc/{{ item.name }}"
+    src: "/var/cache/lxc_{{ item.name }}"
     dest: "/var/cache/lxc/"
     copy: "no"
   with_items: lxc_container_caches
+  when: cache_download|changed
   tags:
     - lxc-cache
     - lxc-cache-unarchive
 
-- name: Remove cache tarball
-  file:
-    path: "/var/cache/lxc/{{ item.name }}"
-    state: absent
-  with_items: lxc_container_caches
-  tags:
-    - lxc-cache
-    - lxc-cache-remove