Support for package downgrade

tasks/elasticsearch-Debian.yml

@@ -1,4 +1,14 @@
 ---
+
+- set_fact: force_install=no
+  tags:
+      - always
+
+- set_fact: force_install=yes
+  when: es_allow_downgrades
+  tags:
+      - always
+
 - name: Debian - Add Elasticsearch repository key
   apt_key: url="http://packages.elasticsearch.org/GPG-KEY-elasticsearch" state=present
   when: es_use_repository
@@ -8,7 +18,7 @@
   when: es_use_repository
 
 - name: Debian - Ensure elasticsearch is installed
-  apt: name=elasticsearch{% if es_version is defined and es_version != "" %}={{ es_version }}{% endif %} state=present cache_valid_time=86400
+  apt: name=elasticsearch{% if es_version is defined and es_version != "" %}={{ es_version }}{% endif %} state=present force={{force_install}} cache_valid_time=86400
   when: es_use_repository
   register: elasticsearch_install_from_repo