update elasticsearch w/ ssl & xpack support

roles/elasticsearch/templates/main.conf.j2

@@ -0,0 +1,38 @@
+# ansible_managed
+input {
+  beats {
+    port => 5044
+  }
+  tcp {
+    port => 5000
+    codec => json_lines
+  }
+  udp {
+    port => 5000
+    codec => json_lines
+  }
+}
+
+filter {
+  # Add filters here as needed (grok, mutate, date, etc.)
+}
+
+output {
+  elasticsearch {
+    # Reach Elasticsearch over the shared docker network using its service name.
+    hosts => ["{{ 'https' if elk_tls_enabled else 'http' }}://{{ elk_elasticsearch_client_host }}:9200"]
+{% if elk_effective_security_enabled %}
+    user => "logstash_system"
+    password => "{{ elk_logstash_system_password }}"
+{% endif %}
+{% if elk_tls_enabled %}
+    ssl_enabled => true
+    # Public CA (Let's Encrypt) - trusted by Logstash's default JVM trust
+    # store already, no custom CA needs to be supplied here.
+{% endif %}
+    index => "logstash-%{+YYYY.MM.dd}"
+  }
+
+  # Uncomment for local debugging of pipeline output:
+  # stdout { codec => rubydebug }
+}