gistfile1.txt

{
  "aggs": {
    "2": {
      "date_histogram": {
        "field": "timestamp",
        "fixed_interval": "60m",
        "time_zone": "UTC",
        "min_doc_count": 1
      },
      "aggs": {
        "3": {
          "terms": {
            "field": "customer",
            "order": {
              "_count": "desc"
            },
            "size": 1
          }
        }
      }
    }
  },
  "size": 0,
  "stored_fields": [
    "*"
  ],
  "script_fields": {},
  "docvalue_fields": [
    {
      "field": "timestamp",
      "format": "date_time"
    }
  ],
  "_source": {
    "excludes": []
  },
  "query": {
    "bool": {
      "must": [],
      "filter": [
        {
          "term" : {
            "customer": "[some-customer]"
          }
        },
        {
          "range": {
            "timestamp": {
              "gte": "2020-10-20T18:00:00.000Z",
              "lte": "2020-10-20T21:59:59.999Z",
              "format": "strict_date_optional_time"
            }
          }
        }
      ],
      "should": [],
      "must_not": []
    }
  }
}