Prometheus: Fix label names select component when there are too many options (#92026)

* add more doc info for truncate function and how we use it

* truncate label names and allow users to search all labels on typing

* remove unused import

* handle labels select in variable query in addition with truncated list

packages/grafana-prometheus/src/components/VariableQueryEditor.tsx

@@ -1,11 +1,13 @@
 // Core Grafana history https://github.com/grafana/grafana/blob/v11.0.0-preview/public/app/plugins/datasource/prometheus/components/VariableQueryEditor.tsx
+import debounce from 'debounce-promise';
 import { FormEvent, useCallback, useEffect, useState } from 'react';
 
 import { QueryEditorProps, SelectableValue } from '@grafana/data';
 import { selectors } from '@grafana/e2e-selectors';
-import { InlineField, InlineFieldRow, Input, Select, TextArea } from '@grafana/ui';
+import { AsyncSelect, InlineField, InlineFieldRow, Input, Select, TextArea } from '@grafana/ui';
 
 import { PrometheusDatasource } from '../datasource';
+import { truncateResult } from '../language_utils';
 import {
   migrateVariableEditorBackToVariableSupport,
   migrateVariableQueryToEditor,
@@ -56,7 +58,20 @@ export const PromVariableQueryEditor = ({ onChange, query, datasource, range }:
   const [classicQuery, setClassicQuery] = useState('');
 
   // list of label names for label_values(), /api/v1/labels, contains the same results as label_names() function
-  const [labelOptions, setLabelOptions] = useState<Array<SelectableValue<string>>>([]);
+  const [truncatedLabelOptions, setTruncatedLabelOptions] = useState<Array<SelectableValue<string>>>([]);
+  const [allLabelOptions, setAllLabelOptions] = useState<Array<SelectableValue<string>>>([]);
+
+  /**
+   * Set the both allLabels and truncatedLabels
+   *
+   * @param names
+   * @param variables
+   */
+  function setLabels(names: SelectableValue[], variables: SelectableValue[]) {
+    setAllLabelOptions([...variables, ...names]);
+    const truncatedNames = truncateResult(names);
+    setTruncatedLabelOptions([...variables, ...truncatedNames]);
+  }
 
   // label filters have been added as a filter for metrics in label values query type
   const [labelFilters, setLabelFilters] = useState<QueryBuilderLabelFilter[]>([]);
@@ -100,7 +115,7 @@ export const PromVariableQueryEditor = ({ onChange, query, datasource, range }:
       // get all the labels
       datasource.getTagKeys({ filters: [] }).then((labelNames: Array<{ text: string }>) => {
         const names = labelNames.map(({ text }) => ({ label: text, value: text }));
-        setLabelOptions([...variables, ...names]);
+        setLabels(names, variables);
       });
     } else {
       // fetch the labels filtered by the metric
@@ -110,7 +125,7 @@ export const PromVariableQueryEditor = ({ onChange, query, datasource, range }:
       datasource.languageProvider.fetchLabelsWithMatch(expr).then((labelsIndex: Record<string, string[]>) => {
         const labelNames = Object.keys(labelsIndex);
         const names = labelNames.map((value) => ({ label: value, value: value }));
-        setLabelOptions([...variables, ...names]);
+        setLabels(names, variables);
       });
     }
   }, [datasource, qryType, metric]);
@@ -220,6 +235,18 @@ export const PromVariableQueryEditor = ({ onChange, query, datasource, range }:
     return { metric: metric, labels: labelFilters, operations: [] };
   }, [metric, labelFilters]);
 
+  /**
+   * Debounce a search through all the labels possible and truncate by .
+   */
+  const labelNamesSearch = debounce((query: string) => {
+    // we limit the select to show 1000 options,
+    // but we still search through all the possible options
+    const results = allLabelOptions.filter((label) => {
+      return label.value?.includes(query);
+    });
+    return truncateResult(results);
+  }, 300);
+
   return (
     <>
       <InlineFieldRow>
@@ -256,14 +283,15 @@ export const PromVariableQueryEditor = ({ onChange, query, datasource, range }:
                 </div>
               }
             >
-              <Select
+              <AsyncSelect
                 aria-label="label-select"
                 onChange={onLabelChange}
                 value={label}
-                options={labelOptions}
+                defaultOptions={truncatedLabelOptions}
                 width={25}
                 allowCustomValue
                 isClearable={true}
+                loadOptions={labelNamesSearch}
                 data-testid={selectors.components.DataSource.Prometheus.variableQueryEditor.labelValues.labelSelect}
               />
             </InlineField>

packages/grafana-prometheus/src/language_utils.ts

@@ -526,6 +526,16 @@ export function getPrometheusTime(date: string | DateTime, roundUp: boolean) {
   return Math.ceil(date.valueOf() / 1000);
 }
 
+/**
+ * Used to truncate metrics, label names and label value in the query builder select components
+ * to improve frontend performance. This is best used with an async select component including
+ * the loadOptions property where we should still allow users to search all results with a string.
+ * This can be done either storing the total results or querying an api that allows for matching a query.
+ *
+ * @param array
+ * @param limit
+ * @returns
+ */
 export function truncateResult<T>(array: T[], limit?: number): T[] {
   if (limit === undefined) {
     limit = PROMETHEUS_QUERY_BUILDER_MAX_RESULTS;

packages/grafana-prometheus/src/querybuilder/components/LabelFilterItem.tsx

@@ -46,6 +46,7 @@ export function LabelFilterItem({
   // instead, we explicitly control the menu visibility and prevent showing it until the options have fully loaded
   const [labelNamesMenuOpen, setLabelNamesMenuOpen] = useState(false);
   const [labelValuesMenuOpen, setLabelValuesMenuOpen] = useState(false);
+  const [allLabels, setAllLabels] = useState<SelectableValue[]>([]);
 
   const isMultiSelect = (operator = item.op) => {
     return operators.find((op) => op.label === operator)?.isMultiValue;
@@ -73,13 +74,25 @@ export function LabelFilterItem({
     debounceDuration
   );
 
+  /**
+   * Debounce a search through all the labels possible and truncate by .
+   */
+  const labelNamesSearch = debounce((query: string) => {
+    // we limit the select to show 1000 options,
+    // but we still search through all the possible options
+    const results = allLabels.filter((label) => {
+      return label.value.includes(query);
+    });
+    return truncateResult(results);
+  }, debounceDuration);
+
   const itemValue = item?.value ?? '';
 
   return (
     <div key={itemValue} data-testid="prometheus-dimensions-filter-item">
       <InputGroup>
         {/* Label name select, loads all values at once */}
-        <Select
+        <AsyncSelect
           placeholder="Select label"
           data-testid={selectors.components.QueryBuilder.labelSelect}
           inputId="prometheus-dimensions-filter-item-key"
@@ -89,15 +102,20 @@ export function LabelFilterItem({
           onOpenMenu={async () => {
             setState({ isLoadingLabelNames: true });
             const labelNames = await onGetLabelNames(item);
+            // store all label names to allow for full label searching by typing in the select option, see loadOptions function labelNamesSearch
+            setAllLabels(labelNames);
             setLabelNamesMenuOpen(true);
-            setState({ labelNames, isLoadingLabelNames: undefined });
+            // truncate the results the same amount as the metric select
+            const truncatedLabelNames = truncateResult(labelNames);
+            setState({ labelNames: truncatedLabelNames, isLoadingLabelNames: undefined });
           }}
           onCloseMenu={() => {
             setLabelNamesMenuOpen(false);
           }}
           isOpen={labelNamesMenuOpen}
           isLoading={state.isLoadingLabelNames ?? false}
-          options={state.labelNames}
+          loadOptions={labelNamesSearch}
+          defaultOptions={state.labelNames}
           onChange={(change) => {
             if (change.label) {
               onChange({

packages/grafana-prometheus/src/querybuilder/components/LabelFilters.test.tsx

@@ -1,14 +1,28 @@
 // Core Grafana history https://github.com/grafana/grafana/blob/v11.0.0-preview/public/app/plugins/datasource/prometheus/querybuilder/components/LabelFilters.test.tsx
-import { render, screen } from '@testing-library/react';
+import { render, screen, waitFor } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 import { ComponentProps } from 'react';
 
+import { selectors } from '@grafana/e2e-selectors';
+
 import { selectOptionInTest } from '../../test/helpers/selectOptionInTest';
 import { getLabelSelects } from '../testUtils';
 
 import { LabelFilters, MISSING_LABEL_FILTER_ERROR_MESSAGE, LabelFiltersProps } from './LabelFilters';
 
 describe('LabelFilters', () => {
+  it('truncates list of label names to 1000', async () => {
+    const manyMockValues = [...Array(1001).keys()].map((idx: number) => {
+      return { label: 'random_label' + idx };
+    });
+
+    setup({ onGetLabelNames: jest.fn().mockResolvedValue(manyMockValues) });
+
+    await openLabelNamesSelect();
+
+    await waitFor(() => expect(screen.getAllByTestId(selectors.components.Select.option)).toHaveLength(1000));
+  });
+
   it('renders empty input without labels', async () => {
     setup();
     expect(screen.getAllByText('Select label')).toHaveLength(1);
@@ -162,3 +176,8 @@ function setup(propOverrides?: Partial<ComponentProps<typeof LabelFilters>>) {
 function getAddButton() {
   return screen.getByLabelText(/Add/);
 }
+
+async function openLabelNamesSelect() {
+  const select = screen.getByText('Select label').parentElement!;
+  await userEvent.click(select);
+}