title: EC2 instance not joining ECS Cluster
body: <p>I have an EC2 cluster and I'm trying to add EC2 machines to it.</p>
  
  <p>I have added <code>ECS_CLUSTER=cluster_name</code> to <code>/etc/ecs/ecs.config</code> with <em>user data</em> but the instance doesn't join the cluster.</p>
  
  <p>I'm looking for log files or any other evidence of the cluster-joining process that may indicate why my instance is not joining.  I do not have a <code>/var/log/ecs</code> folder.</p>