solr as tomcat webapp: try to figure out the tomcat version.

library/roles/solr-tomcat-core-conf/defaults/main.yml

@@ -1,7 +1,6 @@
 ---
 solr_http_port: 8983
 tomcat_load_additional_default_conf: True
-tomcat_version: 7
 # solr needs a lot of time to start if it needs to rebuild its indices
 tomcat_restart_timeout: 100000
 

library/roles/solr-tomcat-core-conf/tasks/main.yml

@@ -1,4 +1,26 @@
 ---
+- name: Set the tomcat version for ubuntu Trusy
+  set_fact:
+    tomcat_version: 7
+  when:
+    - ansible_distribution_major_version <= '16'
+    - tomcat_fixed_version is not defined
+  tags: [ solr, tomcat, solr_core ]
+
+- name: Set the tomcat version for Ubuntu bionic
+  set_fact:
+    tomcat_version: 8
+  when:
+    - ansible_distribution_major_version == '18'
+    - tomcat_fixed_version is not defined
+  tags: [ solr, tomcat, solr_core ]
+
+- name: Impose a tomcat version
+  set_fact:
+    tomcat_version: '{{ tomcat_fixed_version }}'
+  when: tomcat_fixed_version is defined
+  tags: [ solr, tomcat, solr_core ]
+
 - block:
   - name: Create the solr cores data directories
     file: dest={{ solr_collections_base_dir }}/{{ item }} state=directory owner={{ solr_user }} group={{ solr_user }}