$ curl -X GET "https://_domain_/admin/api/services/3337/metrics.json?access_token=_token_" -k | jq .
{
  "metrics": [
    {
      "metric": {
        "id": 8090,
        "name": "hits",
        "system_name": "hits",
        "friendly_name": "Hits",
        "description": "Number of API hits",
        "unit": "hit",
        "created_at": "2021-08-23T11:48:23Z",
        "updated_at": "2021-08-23T11:48:23Z",
        "links": [
          {
            "rel": "service",
            "href": "https://_domain_/admin/api/services/3337"
          },
          {
            "rel": "self",
            "href": "https://_domain_/admin/api/services/3337/metrics/8090"
          }
        ]
      }
    },
    {
      "metric": {
        "id": 8122,
        "name": "hitiky",
        "system_name": "hitiky",
        "friendly_name": "Hitiky",
        "description": "",
        "unit": "hit",
        "parent_id": 8090,
        "created_at": "2021-08-24T10:34:17Z",
        "updated_at": "2021-08-24T10:34:17Z",
        "links": [
          {
            "rel": "service",
            "href": "https://_domain_/admin/api/services/3337"
          },
          {
            "rel": "self",
            "href": "https://_domain_/admin/api/services/3337/metrics/8122"
          }
        ]
      }
    },
    {
      "metric": {
        "id": 8123,
        "name": "hitiky2",
        "system_name": "hitiky2",
        "friendly_name": "Hitiky2",
        "description": "",
        "unit": "hit",
        "parent_id": 8090,
        "created_at": "2021-08-24T10:34:27Z",
        "updated_at": "2021-08-24T10:34:27Z",
        "links": [
          {
            "rel": "service",
            "href": "https://_domain_/admin/api/services/3337"
          },
          {
            "rel": "self",
            "href": "https://_domain_/admin/api/services/3337/metrics/8123"
          }
        ]
      }
    },
    {
      "metric": {
        "id": 8124,
        "name": "ggg",
        "system_name": "ggg",
        "friendly_name": "ggg",
        "description": "",
        "unit": "hit",
        "created_at": "2021-08-24T10:34:43Z",
        "updated_at": "2021-08-24T10:34:43Z",
        "links": [
          {
            "rel": "service",
            "href": "https://_domain_/admin/api/services/3337"
          },
          {
            "rel": "self",
            "href": "https://_domain_/admin/api/services/3337/metrics/8124"
          }
        ]
      }
    }
  ]
}