analyticstack enable yarn log retention (#3149)

CHANGELOG.md

+- Role: hadoop_common
+  - Enable log retention by default to assist with debugging. Now YARN will retain stdout and stderr logs produced by map reduce tasks for 24 hours. They can be retrieved by running "yarn logs -applicationId YOUR_APPLICATION_ID".
+
 - Role: rabbitmq
   - Removed the RABBITMQ_CLUSTERED var and related tooling. The goal of the var was to be able to setup a cluster in the aws environment without having to know all the IPs of the cluster before hand.  It relied on the `hostvars` ansible varible to work correctly which it no longer does in 1.9.  This may get fixed in the future but for now, the "magic" setup doesn't work.
   - Changed `rabbitmq_clustered_hosts` to RABBITMQ_CLUSTERED_HOSTS.

playbooks/roles/hadoop_common/defaults/main.yml

@@ -79,4 +79,8 @@ hadoop_common_redhat_pkgs: []
 #   yarn.nodemanager.vmem-pmem-ratio: 2.1
 
 mapred_site_config: {}
-yarn_site_config: {}
+yarn_site_config:
+  yarn.log-aggregation-enable: true
+  # 24 hour log retention
+  yarn.log-aggregation.retain-seconds: 86400
+