Querying the Grail

Querying Grail from Apps

Two ways to query DQL from a Dynatrace app:

Method                                SDK Package                         Best For
────────────────────────────────────  ──────────────────────────────────  ──────────────────
useDqlQuery (hook)                    @dynatrace-sdk/react-hooks          Simple queries in components
queryExecutionClient (imperative)     @dynatrace-sdk/client-query         Custom polling, error handling

useDqlQuery — The Simple Way

import { useDqlQuery } from "@dynatrace-sdk/react-hooks";

const result = useDqlQuery({
  body: { query: `fetch dt.entity.host | fields entity.name, cpuCores, osType | limit 10` }
});

// result.data    — query results
// result.isLoading — loading state
// result.error   — error if any

queryExecutionClient — Full Control

From the real Host Health Monitor app (deployed, auto-refreshes every 30 seconds). This is a custom wrapper — not the SDK's useDql hook:

import { queryExecutionClient } from "@dynatrace-sdk/client-query";
import { useState, useEffect, useCallback } from "react";

export function useDql(query: string) {
  const [data, setData] = useState<Record<string, unknown>[]>([]);
  const [loading, setLoading] = useState(true);

  const run = useCallback(() => {
    queryExecutionClient
      .queryExecute({ body: { query, requestTimeoutMilliseconds: 30000, maxResultRecords: 1000 } })
      .then((res) => { setData(res.result?.records ?? []); setLoading(false); })
      .catch(() => setLoading(false));
  }, [query]);

  useEffect(() => {
    run();
    const id = setInterval(run, 30_000);
    return () => clearInterval(id);
  }, [run]);

  return { data, loading };
}

Available Data

DQL Fetch Target          What You Get                    Scope Needed
────────────────────────  ──────────────────────────────  ──────────────────
dt.entity.host            Hosts, CPU, memory, OS          storage:entities:read
dt.entity.service         Services, technology            storage:entities:read
fetch logs                Log records                     storage:logs:read
fetch events              Davis events and problems       storage:events:read
fetch bizevents           Business events                 storage:bizevents:read
timeseries                Metric time series              storage:metrics:read
dt.davis.slo              SLO status and targets          storage:events:read