Describe the enhancement:

We should introduce a new setting for the Metricbeat elasticsearch module that would tell the module whether each item in the hosts list represents an individual node in an Elasticsearch cluster, or whether it represents a single node per cluster, or a single load-balancing proxy endpoint per cluster.

Depending on this, the module would do the right thing to collect monitoring data for all ES nodes.

Describe a specific use case for the enhancement or feature:

The Metricbeat elasticsearch module was designed with the assumption that each item in the hosts list would be the address of a single Elasticsearch node in a cluster. This assumption breaks down in a Cloud scenario when Metricbeat is deployed "outside" the Cloud environment and can only talk to a load-balancing proxy that routes requests to a randomly-selected single Elasticsearch node each time.