GET _cluster/allocation/explain?pretty

cluster-explain

{
  "index": "auditbeat-6.2.4-2018.07.20",
  "shard": 2,
  "primary": false,
  "current_state": "unassigned",
  "unassigned_info": {
    "reason": "CLUSTER_RECOVERED",
    "at": "2018-07-23T18:22:23.588Z",
    "last_allocation_status": "no_attempt"
  },
  "can_allocate": "no",
  "allocate_explanation": "cannot allocate because allocation is not permitted to any of the nodes",
  "node_allocation_decisions": [
    {
      "node_id": "v_6xwiPZRJis8XUP7O1UDQ",
      "node_name": "srloggingsb01-elastic-logstash-container-95c16f1e",
      "transport_address": "172.29.239.83:9300",
      "node_attributes": {
        "ml.machine_memory": "84159528960",
        "ml.max_open_jobs": "20",
        "xpack.installed": "true",
        "ml.enabled": "true"
      },
      "node_decision": "no",
      "deciders": [
        {
          "decider": "same_shard",
          "decision": "NO",
          "explanation": "the shard cannot be allocated to the same node on which a copy of the shard already exists [[auditbeat-6.2.4-2018.07.20][2], node[v_6xwiPZRJis8XUP7O1UDQ], [P], s[STARTED], a[id=-ksAWDTbSQyoNZWl8WURpw]]"
        }
      ]
    }
  ]
}