[Infrastructure UI] Filter out null bucket items from average calcula…

…tion (elastic#152333)

## Summary

Closes [elastic#152328](elastic#152328)

This PR fixes the average calculation in the Snapshot API, filtering out
buckets with null values from it, which are more likely to appear with
queries that use small data ranges.

The results after this change are equal to what Elasticsearch would
calculate in the avg aggregation

### How to test

- Make sure you have metrics data (either through enabling the system
module in metricbeat or connecting your local kibana to an oblt-cli
cluster)
- Navigate to `Infrastructure` > `Hosts`
- Filter the results to see a single host
- Change the data range filter and compare the KPIs against the table.
- Validate other pages that use the Snapshot API (Inventory UI and
Metrics UI to see if the results there are still correct

---------

Co-authored-by: Kibana Machine <[email protected]>
(cherry picked from commit f6a0b88)

x-pack/plugins/infra/common/http_api/snapshot_api.ts

@@ -115,6 +115,7 @@ export const SnapshotRequestRT = rt.intersection([
     region: rt.string,
     filterQuery: rt.union([rt.string, rt.null]),
     overrideCompositeSize: rt.number,
+    dropPartialBuckets: rt.boolean,
   }),
 ]);
 

x-pack/plugins/infra/public/pages/metrics/hosts/components/kpi_charts/tile.tsx

@@ -22,6 +22,7 @@ export const Tile = ({ type, ...props }: Props) => {
     metrics: [{ type }],
     groupBy: null,
     includeTimeseries: true,
+    dropPartialBuckets: false,
   });
 
   return <KPIChart id={`$metric-${type}`} type={type} nodes={nodes} loading={loading} {...props} />;

x-pack/plugins/infra/public/pages/metrics/inventory_view/hooks/use_snaphot.ts

@@ -34,6 +34,7 @@ export function useSnapshot({
   groupBy = null,
   sendRequestImmediately = true,
   includeTimeseries = true,
+  dropPartialBuckets = true,
   requestTs,
   ...args
 }: UseSnapshotRequest) {
@@ -56,6 +57,7 @@ export function useSnapshot({
       lookbackSize: 5,
     },
     includeTimeseries,
+    dropPartialBuckets,
   };
 
   const { error, loading, response, makeRequest } = useHTTPRequest(

x-pack/plugins/infra/server/routes/snapshot/lib/transform_metrics_ui_response.ts

@@ -23,15 +23,16 @@ import { applyMetadataToLastPath } from './apply_metadata_to_last_path';
 const getMetricValue = (row: MetricsAPIRow) => {
   if (!isNumber(row.metric_0)) return null;
   const value = row.metric_0;
-  return isFinite(value) ? value : null;
+  return Number.isFinite(value) ? value : null;
 };
 
 const calculateMax = (rows: MetricsAPIRow[]) => {
   return max(rows.map(getMetricValue)) || 0;
 };
 
 const calculateAvg = (rows: MetricsAPIRow[]): number => {
-  return sum(rows.map(getMetricValue)) / rows.length || 0;
+  const values = rows.map(getMetricValue).filter(Number.isFinite);
+  return sum(values) / Math.max(values.length, 1);
 };
 
 const getLastValue = (rows: MetricsAPIRow[]) => {

x-pack/plugins/infra/server/routes/snapshot/lib/transform_request_to_metrics_api_request.ts

@@ -45,7 +45,7 @@ export const transformRequestToMetricsAPIRequest = async ({
       ? snapshotRequest.overrideCompositeSize
       : compositeSize,
     alignDataToEnd: true,
-    dropPartialBuckets: true,
+    dropPartialBuckets: snapshotRequest.dropPartialBuckets ?? true,
     includeTimeseries: snapshotRequest.includeTimeseries,
   };
 

x-pack/test/api_integration/apis/metrics_ui/snapshot.ts

@@ -248,7 +248,7 @@ export default function ({ getService }: FtrProviderContext) {
           name: 'cpu',
           value: null,
           max: 0.47105555555555556,
-          avg: 0.0672936507936508,
+          avg: 0.47105555555555556,
         };
 
         expect(snapshot).to.have.property('nodes');