Merge pull request #702 from edx/cg/worker_hostname

Supervisor doesn't resolve `hostname` so using ansible variable

playbooks/roles/edxapp/templates/workers.conf.j2

@@ -7,7 +7,7 @@ directory={{ edxapp_code_dir }}
 stdout_logfile={{ supervisor_log_dir }}/%(program_name)-stdout.log
 stderr_logfile={{ supervisor_log_dir }}/%(program_name)-stderr.log
 
-command={{ edxapp_venv_bin}}/python {{ edxapp_code_dir }}/manage.py {{ w.service_variant }} --settings=aws celery worker --loglevel=info --queues=edx.{{ w.service_variant }}.core.{{ w.queue }} --hostname=edx.{{ w.service_variant }}.core.{{ w.queue }}.`hostname` --concurrency={{ w.concurrency }}
+command={{ edxapp_venv_bin}}/python {{ edxapp_code_dir }}/manage.py {{ w.service_variant }} --settings=aws celery worker --loglevel=info --queues=edx.{{ w.service_variant }}.core.{{ w.queue }} --hostname=edx.{{ w.service_variant }}.core.{{ w.queue }}.{{ ansible_hostname }} --concurrency={{ w.concurrency }}
 killasgroup=true
 stopasgroup=true