[APM] Fix service maps when root transaction has a parent.id

src/platform/packages/shared/kbn-apm-synthtrace-client/src/lib/dsl/service_map.ts

@@ -12,6 +12,7 @@ import { apm } from '../apm';
 import { Instance } from '../apm/instance';
 import { elasticsearchSpan, redisSpan, sqliteSpan, Span } from '../apm/span';
 import { Transaction } from '../apm/transaction';
+import { generateShortId } from '../utils/generate_id';
 
 const ENVIRONMENT = 'Synthtrace: service_map';
 
@@ -116,6 +117,7 @@ export interface ServiceMapOpts {
   services: Array<string | { [serviceName: string]: AgentName }>;
   definePaths: (services: Instance[]) => PathDef[];
   environment?: string;
+  rootWithParent?: boolean;
 }
 
 export function serviceMap(options: ServiceMapOpts) {
@@ -145,7 +147,10 @@ export function serviceMap(options: ServiceMapOpts) {
         .transaction({ transactionName, transactionType: 'request' })
         .timestamp(timestamp)
         .duration(1000)
-        .children(...getChildren(tracePath, firstTraceItem.serviceInstance, timestamp, index));
+        .children(...getChildren(tracePath, firstTraceItem.serviceInstance, timestamp, index))
+        .defaults({
+          'parent.id': options.rootWithParent ? generateShortId() : undefined,
+        });
 
       if ('transaction' in traceDef && traceDef.transaction) {
         return traceDef.transaction(transaction);

x-pack/solutions/observability/plugins/apm/server/routes/service_map/fetch_service_paths_from_trace_ids.ts

@@ -176,90 +176,86 @@ export async function fetchServicePathsFromTraceIds({
             }
 
             def processAndReturnEvent(def context, def eventId) {
-              def stack = new Stack();
-              def reprocessQueue = new LinkedList();
-
-              // Avoid reprocessing the same event
+              def pathStack = new Stack();
               def visited = new HashSet();
 
-              stack.push(eventId);
+              def event = context.eventsById.get(eventId);
+
+              if (event == null) {
+                return null;
+              }
+
+              pathStack.push(eventId);
+
+              // build a stack with the path from the current event to the root
+              def parentId = event['parent.id'];
+              while (parentId != null && !parentId.equals(eventId)) {
+                def parent = context.eventsById.get(parentId);
+                if (parent == null || visited.contains(parentId)) {
+                  break;
+                }
+
+                pathStack.push(parentId);
+                visited.add(parentId);
+                parentId = parent['parent.id'];
+              }
 
-              while (!stack.isEmpty()) {
-                def currentEventId = stack.pop();
-                def event = context.eventsById.get(currentEventId);
+              // pop the stack starting from the root to current event to build the path
+              while (!pathStack.isEmpty()) {
+                def currentEventId = pathStack.pop();
+                def currentEvent = context.eventsById.get(currentEventId);
+
+                def basePath = new ArrayList();
 
-                if (event == null || context.processedEvents.get(currentEventId) != null) {
+                if (currentEvent == null || context.processedEvents.get(currentEventId) != null) {
                   continue;
                 }
-                visited.add(currentEventId);
 
                 def service = new HashMap();
-                service['service.name'] = event['service.name'];
-                service['service.environment'] = event['service.environment'];
-                service['agent.name'] = event['agent.name'];
-
-                def basePath = new ArrayList();
-                def parentId = event['parent.id'];
-
-                if (parentId != null && !parentId.equals(currentEventId)) {
-                  def parent = context.processedEvents.get(parentId);
-
-                  if (parent == null) {
-
-                    // Only adds the parentId to the stack if it hasn't been visited to prevent infinite loop scenarios
-                    // if the parent is null, it means it hasn't been processed yet or it could also mean that the current event
-                    // doesn't have a parent, in which case we should skip it
-                    if (!visited.contains(parentId)) {
-                      stack.push(parentId);
-                      // Add currentEventId to be reprocessed once its parent is processed
-                      reprocessQueue.add(currentEventId); 
-                    }
-
-
-                    continue;
-                  }
+                service['service.name'] = currentEvent['service.name'];
+                service['service.environment'] = currentEvent['service.environment'];
+                service['agent.name'] = currentEvent['agent.name'];
+
+                def currentParentId = currentEvent['parent.id'];
+                def parent = currentParentId != null ? context.processedEvents.get(currentParentId) : null;
 
+                if (parent != null) {
                   // copy the path from the parent
                   basePath.addAll(parent.path);
                   // flag parent path for removal, as it has children
                   context.locationsToRemove.add(parent.path);
-      
+
                   // if the parent has 'span.destination.service.resource' set, and the service is different, we've discovered a service
                   if (parent['span.destination.service.resource'] != null
                     && parent['span.destination.service.resource'] != ""
-                    && (parent['service.name'] != event['service.name']
-                      || parent['service.environment'] != event['service.environment'])
+                    && (parent['service.name'] != currentEvent['service.name']
+                      || parent['service.environment'] != currentEvent['service.environment'])
                   ) {
                     def parentDestination = getDestination(parent);
                     context.externalToServiceMap.put(parentDestination, service);
                   }
                 }
-          
+
                 def lastLocation = basePath.size() > 0 ? basePath[basePath.size() - 1] : null;
                 def currentLocation = service;
-        
+
                 // only add the current location to the path if it's different from the last one
                 if (lastLocation == null || !lastLocation.equals(currentLocation)) {
                   basePath.add(currentLocation);
                 }
-        
+
                 // if there is an outgoing span, create a new path
-                if (event['span.destination.service.resource'] != null
-                  && !event['span.destination.service.resource'].equals("")) {
+                if (currentEvent['span.destination.service.resource'] != null
+                  && !currentEvent['span.destination.service.resource'].equals("")) {
 
-                  def outgoingLocation = getDestination(event);
+                  def outgoingLocation = getDestination(currentEvent);
                   def outgoingPath = new ArrayList(basePath);
                   outgoingPath.add(outgoingLocation);
                   context.paths.add(outgoingPath);
                 }
-
-                event.path = basePath;
-                context.processedEvents[currentEventId] = event;
 
-                // reprocess events which were waiting for their parents to be processed
-                while (!reprocessQueue.isEmpty()) {
-                  stack.push(reprocessQueue.remove());
-                }
+                currentEvent.path = basePath;
+                context.processedEvents[currentEventId] = currentEvent;
               }
 
               return null;

x-pack/test/api_integration/deployment_agnostic/apis/observability/apm/service_maps/service_maps.spec.ts

@@ -9,6 +9,7 @@ import type { ApmSynthtraceEsClient } from '@kbn/apm-synthtrace';
 import expect from 'expect';
 import { serviceMap, timerange } from '@kbn/apm-synthtrace-client';
 import { Readable } from 'node:stream';
+import { APIReturnType } from '@kbn/apm-plugin/public/services/rest/create_call_apm_api';
 import type { SupertestReturnType } from '../../../../../../apm_api_integration/common/apm_api_supertest';
 import type { DeploymentAgnosticFtrProviderContext } from '../../../../ftr_provider_context';
 
@@ -152,5 +153,84 @@ export default function ({ getService }: DeploymentAgnosticFtrProviderContext) {
         expect(response.body.elements.length).toBeGreaterThan(0);
       });
     });
+
+    describe('Root transaction with parent.id', () => {
+      let synthtraceEsClient: ApmSynthtraceEsClient;
+
+      before(async () => {
+        synthtraceEsClient = await synthtrace.createApmSynthtraceEsClient();
+
+        const events = timerange(start, end)
+          .interval('10s')
+          .rate(3)
+          .generator(
+            serviceMap({
+              services: [
+                { 'frontend-rum': 'rum-js' },
+                { 'frontend-node': 'nodejs' },
+                { advertService: 'java' },
+              ],
+              definePaths([rum, node, adv]) {
+                return [
+                  [
+                    [rum, 'fetchAd'],
+                    [node, 'GET /nodejs/adTag'],
+                    [adv, 'APIRestController#getAd'],
+                    ['elasticsearch', 'GET ad-*/_search'],
+                  ],
+                ];
+              },
+              rootWithParent: true,
+            })
+          );
+
+        return synthtraceEsClient.index(Readable.from(Array.from(events)));
+      });
+
+      after(async () => {
+        await synthtraceEsClient.clean();
+      });
+
+      it('returns service map complete path', async () => {
+        const { body, status } = await apmApiClient.readUser({
+          endpoint: 'GET /internal/apm/service-map',
+          params: {
+            query: {
+              start: new Date(start).toISOString(),
+              end: new Date(end).toISOString(),
+              environment: 'ENVIRONMENT_ALL',
+            },
+          },
+        });
+
+        expect(status).toBe(200);
+
+        const { nodes, edges } = partitionElements(body.elements);
+
+        expect(getIds(nodes)).toEqual([
+          '>elasticsearch',
+          'advertService',
+          'frontend-node',
+          'frontend-rum',
+        ]);
+        expect(getIds(edges)).toEqual([
+          'advertService~>elasticsearch',
+          'frontend-node~advertService',
+          'frontend-rum~frontend-node',
+        ]);
+      });
+    });
   });
 }
+
+type ConnectionElements = APIReturnType<'GET /internal/apm/service-map'>['elements'];
+
+function partitionElements(elements: ConnectionElements) {
+  const edges = elements.filter(({ data }) => 'source' in data && 'target' in data);
+  const nodes = elements.filter((element) => !edges.includes(element));
+  return { edges, nodes };
+}
+
+function getIds(elements: ConnectionElements) {
+  return elements.map(({ data }) => data.id).sort();
+}