[FEATURE] Add node label to elasticsearch_nodes_roles metric

[pincher95]

Title: Add node label to elasticsearch_nodes_roles for better correlation

Background

The elasticsearch_nodes_roles metric currently exposes these labels:

• cluster
• host
• name
• role

Proposal

Extend elasticsearch_nodes_roles with a node label that contains the Elasticsearch node ID:
ql

Current

elasticsearch_nodes_roles{cluster="prod",host="172.17.0.2",name="es-node-1",role="master"} 1

Proposed

elasticsearch_nodes_roles{cluster="prod",host="172.17.0.2",name="es-node-1",node="49nZYKtiQdGg7Nl_sVsI1A",role="master"} 1Implementation notes:

• The node ID is already available as the key in the nodes map returned by /_nodes/_all/stats, so no extra API calls are needed.

• In code this is essentially changing:

  for nodeID, node := range nodeStatsResp.Nodes {
  // ...
  labels := []string{
  nodeStatsResp.ClusterName,
  node.Host,
  node.Name,
  nodeID, // new label
  role,
  }
  }

  Why this helps

• Makes it possible to reliably join elasticsearch_nodes_roles with node-ID–keyed metrics (e.g. shard-level indices metrics once they expose node too).

• Enables queries such as “shards per role” or “docs per role” by joining on node (e.g. shard-level indices metrics once they expose node too).

• No behavioral or performance impact beyond adding one label; all data comes from existing responses.