Aggregating over histogram buckets

[Mike_Nielsen]

Hi,

I'm just new to writing elastic queries. I have the following, but would like to count the number of histogram buckets, per host, that have a count of 0, and I can't quite seem to get it across the line.

I'll have another cup of coffee and try again, but any hints would be gratefully received!

Thanks!

GET /metricbeat-prd-2017.11.14/_search
{
  "size": 0,
  "aggs": {
    "per_host": {
      "aggs": {
        "per_minute": {
          "date_histogram": {
            "field": "@timestamp",
            "interval": "10s"
          }
        }
      },
      "terms": {
        "size": 10,
        "field": "beat.hostname"
      }
    }
  },
  "query": {
    "bool": {
      "filter": [
        {
          "regexp": {
            "beat.hostname": "appserver[12]"
          }
        },
        {
          "term": {
            "metricset.name": "process"
          }
        },
        {
          "term": {
            "system.process.username": "wildfly"
          }
        },
        {
          "range": {
            "@timestamp": {
              "lte": "now",
              "gte": "now-2m/m"
            }
          }
        }
      ]
    }
  }
}