One other thing that I'm not sure was clear here -- /cluster/health and /_health_report are two very different things, despite having misleadingly similar names and response colors. /_cluster/health only gives information about whether shards are allocated. /_health_report checks a lot of things throughout the cluster (including shard allocation). So it would not be unusual for /_cluster/health to report green (all shards are allocated) but /_health_report to report yellow (for any of a wide variety of reasons)