[Stack Monitoring] Put elasticsearch.node.stats.jvm.mem.pools.*

[pickypg]

This re-adds the pools to the node_stats metric set.

Proposed commit message

Adds the elasticsearch.node.stats.jvm.mem.pools.* fields to the metricset for node_stats because it was removed by accident in a previous release.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Disruptive User Impact

No. The mappings have continued to exist.

Author's Checklist

• Verify that the data appears in the node_stats metricset

How to test this PR locally

Configure Metricbeat:

metricbeat.modules:
- module: elasticsearch
  metricsets:
    - node_stats
  period: 10s
  hosts: ["http://es:9200"]

output.elasticsearch:
  hosts: ["http://es:9200"]

Connect to Elasticsearch and observe the data stream provides

GET /.ds-metricbeat-*/_search?q=metricset.name:node_stats&filter_path=hits.hits._source.elasticsearch.node.stats.jvm.mem.pools.*

Without this change, this does not exist in the resulting _source. With this change, you should see something along the lines of

{
  "hits" : {
    "hits" : [
      {
        "_source" : {
          "elasticsearch" : {
            "node" : {
              "stats" : {
                "jvm" : {
                  "mem" : {
                    "pools" : {
                      "survivor" : {
                        "peak" : {
                          "bytes" : 74424848
                        },
                        "peak_max" : {
                          "bytes" : 0
                        },
                        "used" : {
                          "bytes" : 12582912
                        },
                        "max" : {
                          "bytes" : 0
                        }
                      },
                      "old" : {
                        "used" : {
                          "bytes" : 90397592
                        },
                        "max" : {
                          "bytes" : 1073741824
                        },
                        "peak" : {
                          "bytes" : 91899520
                        },
                        "peak_max" : {
                          "bytes" : 1073741824
                        }
                      },
                      "young" : {
                        "peak" : {
                          "bytes" : 624951296
                        },
                        "peak_max" : {
                          "bytes" : 0
                        },
                        "used" : {
                          "bytes" : 293601280
                        },
                        "max" : {
                          "bytes" : 0
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    ]
  }
}

Related issues

Closes #40539

Use cases

Understand the different memory pools in the JVM.

[consulthys]

LGTM

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b monitoring/put-back-jvm-pools upstream/monitoring/put-back-jvm-pools
git merge upstream/main
git push upstream monitoring/put-back-jvm-pools