elasticsearch: add condition to whether or not install java.

ansible-role-elasticsearch/defaults/main.yml

@@ -7,3 +7,4 @@ elasticsearch_jvm_xms: null
 elastic_stack_version: 6.1.2
 elasticsearch_shards: 5
 elasticsearch_replicas: 1
+elasticsearch_install_java: yes

ansible-role-elasticsearch/tasks/Debian.yml

@@ -10,6 +10,8 @@
     repo: 'ppa:webupd8team/java'
     codename: 'xenial'
 
+- when: elasticsearch_install_java
+  block:
     - name: Debian/Ubuntu | Accept Oracle Java 8 license
       debconf:
         name: oracle-java8-installer

ansible-role-elasticsearch/tasks/RedHat.yml

@@ -1,4 +1,6 @@
 ---
+- when: elasticsearch_install_java
+  block:
     - name: RedHat/CentOS/Fedora | download Oracle Java RPM
       get_url:
         url: http://download.oracle.com/otn-pub/java/jdk/8u161-b12/2f38c3b165be4555a1fa6e98c45e0808/jre-8u161-linux-x64.rpm
@@ -22,5 +24,5 @@
 
 - name: RedHat/CentOS/Fedora | Install Elasticsarch
   package: name=elasticsearch-{{ elastic_stack_version }} state=present
-  when: oracle_java_task_rpm_installed is defined
+  when: not elasticsearch_install_java or oracle_java_task_rpm_installed is defined
   tags: install