Remove multi instances support (#566)

* remove multi instances support
The goal is to stop supporting installation of more than one node in the same host. This commit update the Ansible role README documentation and remove the multi instances kitchen test.

* remove systemd and init.d templates
As we no more need to support more than one node on the same host, we no more need to override init files provided by elasticsearch official packages.

* remove file script feature
File scripts have been removed since elasticsearch 6.0 (https://www.elastic.co/guide/en/elasticsearch/reference/6.0/breaking_60_scripting_changes.html#_file_scripts_removed)

* remove custom user and custom group
ES_USER and ES_GROUP settings are no longer supported (https://www.elastic.co/guide/en/elasticsearch/reference/6.0/breaking_60_packaging_changes.html#_configuring_custom_user_and_group_for_package_is_no_longer_allowed)

* add upgrade procedure

* use same task for license activation with and without authentication

tasks/xpack/elasticsearch-xpack-install.yml

@@ -10,9 +10,9 @@
   check_mode: no
   ignore_errors: yes
   environment:
-    CONF_DIR: "{{ conf_dir }}"
-    ES_PATH_CONF: "{{ conf_dir }}"
-    ES_INCLUDE: "{{ instance_default_file }}"
+    CONF_DIR: "{{ es_conf_dir }}"
+    ES_PATH_CONF: "{{ es_conf_dir }}"
+    ES_INCLUDE: "{{ default_file }}"
 
 
 #Remove X-Pack if installed and its not been requested or the ES version has changed
@@ -25,9 +25,9 @@
   when: x_pack_installed.rc == 0 and (not es_enable_xpack or es_version_changed)
   notify: restart elasticsearch
   environment:
-    CONF_DIR: "{{ conf_dir }}"
-    ES_PATH_CONF: "{{ conf_dir }}"
-    ES_INCLUDE: "{{ instance_default_file }}"
+    CONF_DIR: "{{ es_conf_dir }}"
+    ES_PATH_CONF: "{{ es_conf_dir }}"
+    ES_INCLUDE: "{{ default_file }}"
 
 
 #Install plugin if not installed, or the es version has changed (so removed above), and its been requested
@@ -44,9 +44,9 @@
   when: (x_pack_installed.rc == 1 or es_version_changed) and (es_enable_xpack and es_xpack_custom_url is defined)
   notify: restart elasticsearch
   environment:
-    CONF_DIR: "{{ conf_dir }}"
-    ES_PATH_CONF: "{{ conf_dir }}"
-    ES_INCLUDE: "{{ instance_default_file }}"
+    CONF_DIR: "{{ es_conf_dir }}"
+    ES_PATH_CONF: "{{ es_conf_dir }}"
+    ES_INCLUDE: "{{ default_file }}"
 
 - name: Delete x-pack zip file
   file: dest=/tmp/x-pack-{{ es_version }}.zip state=absent
@@ -62,7 +62,7 @@
   when: (x_pack_installed.rc == 1 or es_version_changed) and (es_enable_xpack and es_xpack_custom_url is not defined)
   notify: restart elasticsearch
   environment:
-    CONF_DIR: "{{ conf_dir }}"
-    ES_PATH_CONF: "{{ conf_dir }}"
-    ES_INCLUDE: "{{ instance_default_file }}"
+    CONF_DIR: "{{ es_conf_dir }}"
+    ES_PATH_CONF: "{{ es_conf_dir }}"
+    ES_INCLUDE: "{{ default_file }}"
     ES_JAVA_OPTS: "{% if es_proxy_host is defined and es_proxy_host != '' %}-Dhttp.proxyHost={{ es_proxy_host }} -Dhttp.proxyPort={{ es_proxy_port }} -Dhttps.proxyHost={{ es_proxy_host }} -Dhttps.proxyPort={{ es_proxy_port }}{% endif %}"