use ami id and instance id for the hostname

playbooks/roles/newrelic/templates/etc/init/newrelic-logwatch-agent.conf.j2

@@ -4,6 +4,8 @@ stop on runlevel [016]
 respawn
 chdir {{ newrelic_logwatch_dir }} 
 pre-start script
-  sed -i "s/HOSTNAME/$(hostname)/" {{ newrelic_logwatch_dir }}/config/newrelic_plugin.yml
+  instance_id=$(ec2metadata --instance-id)
+  ami_id=$(ec2metadata --ami-id)
+  sed -i "s/HOSTNAME/${ami_id}-${instance_id}/" {{ newrelic_logwatch_dir }}/config/newrelic_plugin.yml
 end script
 exec ruby newrelic_logwatcher_agent.rb