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/security/elasticsearch-security.yml

@@ -5,7 +5,7 @@
 
 #Ensure x-pack conf directory is created if necessary
 - name: Ensure x-pack conf directory exists (file)
-  file: path={{ conf_dir }}{{ es_xpack_conf_subdir }} state=directory owner={{ es_user }} group={{ es_group }}
+  file: path={{ es_conf_dir }}{{ es_xpack_conf_subdir }} state=directory owner={{ es_user }} group={{ es_group }}
   changed_when: False
   when: (es_users is defined and es_users.file is defined) or (es_roles is defined and es_roles.file is defined) or (es_role_mapping is defined)
 
@@ -18,9 +18,9 @@
     command: >
      {{es_home}}/bin/elasticsearch-keystore create
     args:
-      creates: "{{ conf_dir }}/elasticsearch.keystore"
+      creates: "{{ es_conf_dir }}/elasticsearch.keystore"
     environment:
-      ES_PATH_CONF: "{{ conf_dir }}"
+      ES_PATH_CONF: "{{ es_conf_dir }}"
 
   - name: Check if bootstrap password is set
     become: yes
@@ -29,7 +29,7 @@
     register: list_keystore
     changed_when: False
     environment:
-      ES_PATH_CONF: "{{ conf_dir }}"
+      ES_PATH_CONF: "{{ es_conf_dir }}"
     check_mode: no
 
   - name: Create Bootstrap password for elastic user
@@ -38,7 +38,7 @@
     when:
       - es_api_basic_auth_username is defined and list_keystore is defined and es_api_basic_auth_username == 'elastic' and 'bootstrap.password' not in list_keystore.stdout_lines
     environment:
-      ES_PATH_CONF: "{{ conf_dir }}"
+      ES_PATH_CONF: "{{ es_conf_dir }}"
     no_log: true
 ### END BLOCK elasticsearch keystore ###
 
@@ -52,7 +52,7 @@
 #Copy Roles files
 - name: Copy role_mapping.yml File for Instance
   become: yes
-  template: src=security/role_mapping.yml.j2 dest={{conf_dir}}{{es_xpack_conf_subdir}}/role_mapping.yml owner={{ es_user }} group={{ es_group }} mode=0644 force=yes
+  template: src=security/role_mapping.yml.j2 dest={{ es_conf_dir }}{{es_xpack_conf_subdir}}/role_mapping.yml owner={{ es_user }} group={{ es_group }} mode=0644 force=yes
   when: es_role_mapping is defined
 
 #------------------------------------------------------------------------------------
@@ -60,5 +60,5 @@
 #Ensure security conf directory is created
 - name: Ensure security conf directory exists
   become: yes
-  file: path={{ conf_dir }}/security state=directory owner={{ es_user }} group={{ es_group }}
+  file: path={{ es_conf_dir }}/security state=directory owner={{ es_user }} group={{ es_group }}
   changed_when: False