[9.2] [APM] Transaction routes to use accessKnownApmEventFields (elastic#243502) (elastic#243800)

# Backport

This will backport the following commits from `main` to `9.2`:
- [[APM] Transaction routes to use `accessKnownApmEventFields`
(elastic#243502)](elastic#243502)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Gonçalo Rica Pais da
Silva","email":"[email protected]"},"sourceCommit":{"committedDate":"2025-11-21T12:22:48Z","message":"[APM]
Transaction routes to use `accessKnownApmEventFields` (elastic#243502)\n\n##
Summary\n\nCloses
[elastic#243370](https://github.com/elastic/kibana/issues/243370)\n\nThe rest
of the `transaction` routes in APM being updated to make use
of\n`accessKnownApmEventFields`, along with removing some `lodash`
usages\nwhere native JS equivalents are available.\n\n## How to
test\n\n- Go to Discover on an Observability space, select a traces
index (APM\nand/or OTEL) in either Classic or ES|QL.\n- Select a trace
with either an event.outcome as failure or status.code\nas Error. On
spans/transactions with an error attached to it, it should\nshow on both
the focused and full trace waterfall without any issue.\n- Going through
to the APM page via the trace.id link, the APM trace\nwaterfall should
also show the same errors with no issue.\n- Clicking on a trace span
should open up to show the Span details\nwithout issue/regression.\n-
Trace samples should be available without
issue/regression.","sha":"89afdb36bf577a7ec847e85e53cd85eef1283b6d","branchLabelMapping":{"^v9.3.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","Team:obs-ux-infra_services","backport:version","v9.3.0","Team:obs-exploration","ci:beta-faster-pr-build","v8.19.8","v9.2.2","v9.1.8"],"title":"[APM]
Transaction routes to use
`accessKnownApmEventFields`","number":243502,"url":"https://github.com/elastic/kibana/pull/243502","mergeCommit":{"message":"[APM]
Transaction routes to use `accessKnownApmEventFields` (elastic#243502)\n\n##
Summary\n\nCloses
[elastic#243370](https://github.com/elastic/kibana/issues/243370)\n\nThe rest
of the `transaction` routes in APM being updated to make use
of\n`accessKnownApmEventFields`, along with removing some `lodash`
usages\nwhere native JS equivalents are available.\n\n## How to
test\n\n- Go to Discover on an Observability space, select a traces
index (APM\nand/or OTEL) in either Classic or ES|QL.\n- Select a trace
with either an event.outcome as failure or status.code\nas Error. On
spans/transactions with an error attached to it, it should\nshow on both
the focused and full trace waterfall without any issue.\n- Going through
to the APM page via the trace.id link, the APM trace\nwaterfall should
also show the same errors with no issue.\n- Clicking on a trace span
should open up to show the Span details\nwithout issue/regression.\n-
Trace samples should be available without
issue/regression.","sha":"89afdb36bf577a7ec847e85e53cd85eef1283b6d"}},"sourceBranch":"main","suggestedTargetBranches":["8.19","9.2","9.1"],"targetPullRequestStates":[{"branch":"main","label":"v9.3.0","branchLabelMappingKey":"^v9.3.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/243502","number":243502,"mergeCommit":{"message":"[APM]
Transaction routes to use `accessKnownApmEventFields` (elastic#243502)\n\n##
Summary\n\nCloses
[elastic#243370](https://github.com/elastic/kibana/issues/243370)\n\nThe rest
of the `transaction` routes in APM being updated to make use
of\n`accessKnownApmEventFields`, along with removing some `lodash`
usages\nwhere native JS equivalents are available.\n\n## How to
test\n\n- Go to Discover on an Observability space, select a traces
index (APM\nand/or OTEL) in either Classic or ES|QL.\n- Select a trace
with either an event.outcome as failure or status.code\nas Error. On
spans/transactions with an error attached to it, it should\nshow on both
the focused and full trace waterfall without any issue.\n- Going through
to the APM page via the trace.id link, the APM trace\nwaterfall should
also show the same errors with no issue.\n- Clicking on a trace span
should open up to show the Span details\nwithout issue/regression.\n-
Trace samples should be available without
issue/regression.","sha":"89afdb36bf577a7ec847e85e53cd85eef1283b6d"}},{"branch":"8.19","label":"v8.19.8","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"9.2","label":"v9.2.2","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"9.1","label":"v9.1.8","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Gonçalo Rica Pais da Silva <[email protected]>

Author: kibanamachine

x-pack/solutions/observability/plugins/apm/server/routes/transactions/breakdown/index.ts

@@ -5,7 +5,7 @@
  * 2.0.
  */
 
-import { flatten, orderBy, last, clamp, round } from 'lodash';
+import { orderBy, last, clamp, round } from 'lodash';
 import { rangeQuery, kqlQuery } from '@kbn/observability-plugin/server';
 import { ProcessorEvent } from '@kbn/observability-plugin/common';
 import { asPercent } from '../../../../common/utils/formatters';
@@ -136,24 +136,21 @@ export async function getTransactionBreakdown({
   ) => {
     const sumAllSelfTimes = aggs.sum_all_self_times.value || 0;
 
-    const breakdowns = flatten(
-      aggs.types.buckets.map((bucket) => {
-        const type = bucket.key as string;
-
-        return bucket.subtypes.buckets.map((subBucket) => {
-          const percentageRaw =
-            (subBucket.total_self_time_per_subtype.value || 0) / sumAllSelfTimes;
-          // limit percentage from 0% to 100% and
-          // round to 8 decimal points (results in 6 decimal points after converting to percentages) to prevent displaying scientific notation in charts
-          const percentage = round(clamp(percentageRaw, 0, 1), 8);
-
-          return {
-            name: (subBucket.key as string) || type,
-            percentage,
-          };
-        });
-      })
-    );
+    const breakdowns = aggs.types.buckets.flatMap((bucket) => {
+      const type = bucket.key as string;
+
+      return bucket.subtypes.buckets.map((subBucket) => {
+        const percentageRaw = (subBucket.total_self_time_per_subtype.value || 0) / sumAllSelfTimes;
+        // limit percentage from 0% to 100% and
+        // round to 8 decimal points (results in 6 decimal points after converting to percentages) to prevent displaying scientific notation in charts
+        const percentage = round(clamp(percentageRaw, 0, 1), 8);
+
+        return {
+          name: (subBucket.key as string) || type,
+          percentage,
+        };
+      });
+    });
 
     return breakdowns;
   };

x-pack/solutions/observability/plugins/apm/server/routes/transactions/get_span/index.ts

@@ -7,9 +7,9 @@
 
 import { rangeQuery, termQuery } from '@kbn/observability-plugin/server';
 import { ProcessorEvent } from '@kbn/observability-plugin/common';
-import { unflattenKnownApmEventFields } from '@kbn/apm-data-access-plugin/server/utils';
+import { accessKnownApmEventFields } from '@kbn/apm-data-access-plugin/server/utils';
 import type { FlattenedApmEvent } from '@kbn/apm-data-access-plugin/server/utils/utility_types';
-import { merge, omit } from 'lodash';
+import { merge } from 'lodash';
 import { maybe } from '../../../../common/utils/maybe';
 import { SPAN_ID, SPAN_STACKTRACE, TRACE_ID } from '../../../../common/es_fields/apm';
 import { asMutableArray } from '../../../../common/utils/as_mutable_array';
@@ -67,11 +67,16 @@ export async function getSpan({
   const hit = maybe(spanResp.hits.hits[0]);
   const spanFromSource = hit && 'span' in hit._source ? hit._source : undefined;
 
-  const event = unflattenKnownApmEventFields(hit?.fields as undefined | FlattenedApmEvent);
+  const { span, ...event } =
+    (hit?.fields &&
+      accessKnownApmEventFields(hit.fields as Partial<FlattenedApmEvent>).unflatten()) ??
+    {};
+
+  const { links, ...rest } = span ?? {};
 
   return {
-    span: event
-      ? merge({}, omit(event, 'span.links'), spanFromSource, {
+    span: hit
+      ? merge(event, { span: rest }, spanFromSource, {
           processor: { event: 'span' as const, name: 'transaction' as const },
         })
       : undefined,

x-pack/solutions/observability/plugins/apm/server/routes/transactions/get_transaction_by_name/index.ts

@@ -6,7 +6,7 @@
  */
 
 import { rangeQuery } from '@kbn/observability-plugin/server';
-import { unflattenKnownApmEventFields } from '@kbn/apm-data-access-plugin/server/utils';
+import { accessKnownApmEventFields } from '@kbn/apm-data-access-plugin/server/utils';
 import { maybe } from '../../../../common/utils/maybe';
 import { ApmDocumentType } from '../../../../common/document_type';
 import {
@@ -70,5 +70,7 @@ export async function getTransactionByName({
     fields: requiredFields,
   });
 
-  return unflattenKnownApmEventFields(maybe(resp.hits.hits[0])?.fields, requiredFields);
+  const fields = maybe(resp.hits.hits[0])?.fields;
+
+  return fields && accessKnownApmEventFields(fields).requireFields(requiredFields).unflatten();
 }

x-pack/solutions/observability/plugins/apm/server/routes/transactions/get_transaction_by_trace/index.ts

@@ -7,7 +7,7 @@
 
 import { ProcessorEvent } from '@kbn/observability-plugin/common';
 import { rangeQuery } from '@kbn/observability-plugin/server';
-import { unflattenKnownApmEventFields } from '@kbn/apm-data-access-plugin/server/utils';
+import { accessKnownApmEventFields } from '@kbn/apm-data-access-plugin/server/utils';
 import { maybe } from '../../../../common/utils/maybe';
 import { asMutableArray } from '../../../../common/utils/as_mutable_array';
 import {
@@ -92,7 +92,10 @@ export async function getRootTransactionByTraceId({
 
   const resp = await apmEventClient.search('get_root_transaction_by_trace_id', params);
 
-  const event = unflattenKnownApmEventFields(maybe(resp.hits.hits[0])?.fields, requiredFields);
+  const fields = maybe(resp.hits.hits[0])?.fields;
+
+  const event =
+    fields && accessKnownApmEventFields(fields).requireFields(requiredFields).unflatten();
 
   return {
     transaction: event,

x-pack/solutions/observability/plugins/apm/server/routes/transactions/route.ts

@@ -71,8 +71,10 @@ const transactionGroupsMainStatisticsRoute = createApmServerRoute({
   security: { authz: { requiredPrivileges: ['apm'] } },
   handler: async (resources): Promise<MergedServiceTransactionGroupsResponse> => {
     const { params } = resources;
-    const apmEventClient = await getApmEventClient(resources);
-    const apmAlertsClient = await getApmAlertsClient(resources);
+    const [apmEventClient, apmAlertsClient] = await Promise.all([
+      getApmEventClient(resources),
+      getApmAlertsClient(resources),
+    ]);
 
     const {
       path: { serviceName },

x-pack/solutions/observability/plugins/apm/server/routes/transactions/trace_samples/index.ts

@@ -7,7 +7,7 @@
 import type { Sort, QueryDslQueryContainer } from '@elastic/elasticsearch/lib/api/types';
 import { ProcessorEvent } from '@kbn/observability-plugin/common';
 import { kqlQuery, rangeQuery } from '@kbn/observability-plugin/server';
-import { unflattenKnownApmEventFields } from '@kbn/apm-data-access-plugin/server/utils';
+import { accessKnownApmEventFields } from '@kbn/apm-data-access-plugin/server/utils';
 import { asMutableArray } from '../../../../common/utils/as_mutable_array';
 import {
   AT_TIMESTAMP,
@@ -114,12 +114,13 @@ export async function getTraceSamples({
     });
 
     const traceSamples = response.hits.hits.map((hit) => {
-      const event = unflattenKnownApmEventFields(hit.fields, requiredFields);
+      const event = accessKnownApmEventFields(hit.fields).requireFields(requiredFields);
+
       return {
         score: hit._score,
         timestamp: event[AT_TIMESTAMP],
-        transactionId: event.transaction.id,
-        traceId: event.trace.id,
+        transactionId: event[TRANSACTION_ID],
+        traceId: event[TRACE_ID],
       };
     });