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/elasticsearch-config.yml

@@ -6,124 +6,31 @@
   become: yes
   file: path={{ item }} state=directory owner={{ es_user }} group={{ es_group }}
   with_items:
-    - "{{pid_dir}}"
-    - "{{log_dir}}"
-    - "{{conf_dir}}"
-
-- name: Create Data Directories
-  become: yes
-  file: path={{ item }} state=directory owner={{ es_user }} group={{ es_group }}
-  with_items:
-    - "{{data_dirs}}"
+    - "{{ es_pid_dir }}"
+    - "{{ es_log_dir }}"
+    - "{{ es_conf_dir }}"
+    - "{{ es_data_dirs }}"
 
 #Copy the config template
 - name: Copy Configuration File
   become: yes
-  template: src=elasticsearch.yml.j2 dest={{conf_dir}}/elasticsearch.yml owner={{ es_user }} group={{ es_group }} mode=0644 force=yes
+  template: src=elasticsearch.yml.j2 dest={{ es_conf_dir }}/elasticsearch.yml owner={{ es_user }} group={{ es_group }} mode=0644 force=yes
   register: system_change
   notify: restart elasticsearch
 
-#Copy the instance specific default file
-- name: Copy Default File for Instance
+#Copy the default file
+- name: Copy Default File
   become: yes
-  template: src=elasticsearch.j2 dest={{instance_default_file}} mode=0644 force=yes
+  template: src=elasticsearch.j2 dest={{ default_file }} mode=0644 force=yes
   notify: restart elasticsearch
 
-#Copy the instance specific init file
-- name: Copy Debian Init File for Instance
-  become: yes
-  template: src=init/debian/elasticsearch.j2 dest={{instance_init_script}} mode=0755 force=yes
-  when: ansible_os_family == 'Debian' and not use_system_d
-  notify: restart elasticsearch
-
-#Copy the instance specific init file
-- name: Copy Redhat Init File for Instance
-  become: yes
-  template: src=init/redhat/elasticsearch.j2 dest={{instance_init_script}} mode=0755 force=yes
-  when: ansible_os_family == 'RedHat' and not use_system_d
-  notify: restart elasticsearch
-
-#Copy the systemd specific file if systemd is installed
-- name: Copy Systemd File for Instance
-  become: yes
-  template: src=systemd/elasticsearch.j2 dest={{instance_sysd_script}} mode=0644 force=yes
-  when: use_system_d
-  notify:
-  - reload systemd configuration
-  - restart elasticsearch
-
 #Copy the logging.yml
-- name: Copy log4j2.properties File for Instance
+- name: Copy log4j2.properties File
   become: yes
-  template: src={{es_config_log4j2}} dest={{conf_dir}}/log4j2.properties owner={{ es_user }} group={{ es_group }} mode=0644 force=yes
+  template: src={{es_config_log4j2}} dest={{ es_conf_dir }}/log4j2.properties owner={{ es_user }} group={{ es_group }} mode=0644 force=yes
   notify: restart elasticsearch
 
-- name: Copy jvm.options File for Instance
+- name: Copy jvm.options File
   become: yes
-  template: src=jvm.options.j2 dest={{conf_dir}}/jvm.options owner={{ es_user }} group={{ es_group }} mode=0644 force=yes
+  template: src=jvm.options.j2 dest={{ es_conf_dir }}/jvm.options owner={{ es_user }} group={{ es_group }} mode=0644 force=yes
   notify: restart elasticsearch
-
-#Clean up un-wanted package scripts to avoid confusion
-
-- name: Delete Default Init
-  become: yes
-  file: dest=/etc/init.d/elasticsearch state=absent
-
-- name: Create empty default environment file
-  become: yes
-  changed_when: False
-  copy:
-    dest: /etc/default/elasticsearch
-    content: ''
-  when: ansible_os_family == 'Debian'
-
-- name: Create empty default environment file
-  become: yes
-  changed_when: False
-  copy:
-    dest: /etc/sysconfig/elasticsearch
-    content: ''
-  when: ansible_os_family == 'RedHat'
-
-- name: Symlink default systemd service to first instance of elasticsearch
-  when: use_system_d
-  block:
-  - name: Check if default systemd file exists
-    stat:
-      path: "{{ sysd_script }}"
-    register: sysd_stat_result
-    check_mode: no
-
-  - name: Remove if it is a normal file
-    become: yes
-    file:
-      path: "{{ sysd_script }}"
-      state: absent
-    when: sysd_stat_result.stat.exists and not sysd_stat_result.stat.islnk
-
-  - name: Create a symbolic link to the default systemd location to the first instance running on this host
-    become: yes
-    file:
-      state: link
-      src: "{{ instance_sysd_script }}"
-      path: "{{ sysd_script }}"
-    when: sysd_stat_result.stat.exists and not sysd_stat_result.stat.islnk
-    notify:
-    - reload systemd configuration
-    - restart elasticsearch
-
-- name: Delete Default Configuration File
-  become: yes
-  file: dest=/etc/elasticsearch/elasticsearch.yml state=absent
-
-- name: Delete Default Logging File
-  become: yes
-  file: dest=/etc/elasticsearch/logging.yml state=absent
-
-- name: Delete Default Logging File
-  become: yes
-  file: dest=/etc/elasticsearch/log4j2.properties state=absent
-
-- name: Delete Default JVM Options File
-  become: yes
-  file: dest=/etc/elasticsearch/jvm.options state=absent