// Exactly one "target" type should be set.
message ExternalMetricSource {
  // metricName is the name of the metric in question.
  optional string metricName = 1;

  // metricSelector is used to identify a specific time series
  // within a given metric.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.LabelSelector metricSelector = 2;

  // targetValue is the target value of the metric (as a quantity).

  // eventTime is the time when this Event was first observed. It is required.
  optional k8s.io.apimachinery.pkg.apis.meta.v1.MicroTime eventTime = 2;

  // series is data about the Event series this event represents or nil if it's a singleton Event.
  // +optional
  optional EventSeries series = 3;

  // reportingController is the name of the controller that emitted this Event, e.g. `kubernetes.io/kubelet`.
  // This field cannot be empty for new Events.

            "uid": "${datasource}"
          },
          "expr": "round(sum(irate(istio_requests_total{reporter=~\"$qrep\",destination_service=~\"$service\"}[5m])), 0.001)",
          "format": "time_series",
          "intervalFactor": 1,
          "refId": "A",
          "step": 4
        }
      ],
      "title": "Client Request Volume",
      "type": "stat"
    },
    {
      "datasource": {

          "format": "time_series",
          "hide": true,
          "intervalFactor": 2,
          "legendFormat": "heap alloc",
          "refId": "D"
        },
        {
          "datasource": {
            "type": "prometheus",
            "uid": "${datasource}"
          },
          "expr": "go_memstats_alloc_bytes{app=\"istiod\"}",
          "format": "time_series",
          "intervalFactor": 2,

        {
          "datasource": {
            "type": "prometheus",
            "uid": "${datasource}"
          },
          "expr": "sum(istio_build{component=\"pilot\"}) by (tag)",
          "format": "time_series",
          "intervalFactor": 1,
          "legendFormat": "{{ tag }}",
          "refId": "A"
        }
      ],
      "title": "Pilot Versions",
      "type": "timeseries"
    },
    {

  // eventTime is the time when this Event was first observed. It is required.
  optional k8s.io.apimachinery.pkg.apis.meta.v1.MicroTime eventTime = 2;

  // series is data about the Event series this event represents or nil if it's a singleton Event.
  // +optional
  optional EventSeries series = 3;

  // reportingController is the name of the controller that emitted this Event, e.g. `kubernetes.io/kubelet`.
  // This field cannot be empty for new Events.

{ "expr": "process_virtual_memory_bytes{app=\"istiod\"}", "format": "time_series", "instant": false, "intervalFactor": 2, "legendFormat": "Virtual Memory", "refId": "I", "step": 2 }, { "expr": "process_resident_memory_bytes{app=\"istiod\"}", "format": "time_series", "intervalFactor": 2, "legendFormat": "Resident Memory", "refId": "H", "step": 2 }, { "expr": "go_memstats_heap_sys_bytes{app=\"istiod\"}", "format": "time_series", "hide": true, "intervalFactor": 2, "legendFormat": "heap sys", "refId":...

          },
          "expr": "round(sum(irate(istio_requests_total{reporter=~\"$qrep\",destination_workload_namespace=~\"$namespace\",destination_workload=~\"$workload\"}[5m])), 0.001)",
          "format": "time_series",
          "intervalFactor": 1,
          "refId": "A",
          "step": 4
        }
      ],
      "title": "Incoming Request Volume",
      "type": "stat"
    },
    {
      "datasource": {

          },
          "expr": "sum(rate(istio_requests_total{reporter=\"source\", response_code!~\"5.*\"}[1m])) / sum(rate(istio_requests_total{reporter=\"source\"}[1m]))",
          "format": "time_series",
          "intervalFactor": 1,
          "refId": "A",
          "step": 4
        }
      ],
      "title": "Global Success Rate (non-5xx responses)",
      "type": "stat"
    },
    {

  // Time when this Event was first observed.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.MicroTime eventTime = 10;

  // Data about the Event series this event represents or nil if it's a singleton Event.
  // +optional
  optional EventSeries series = 11;

  // What action was taken/failed regarding to the Regarding object.
  // +optional
  optional string action = 12;