[APM] Span link

packages/elastic-apm-synthtrace/src/lib/apm/apm_fields.ts

@@ -85,6 +85,10 @@ export type ApmFields = Fields &
     'span.destination.service.response_time.count': number;
     'span.self_time.count': number;
     'span.self_time.sum.us': number;
+    'span.links': Array<{
+      trace: { id: string };
+      span: { id: string };
+    }>;
     'cloud.provider': string;
     'cloud.project.name': string;
     'cloud.service.name': string;

packages/elastic-apm-synthtrace/src/scripts/examples/04_span_links.ts

@@ -0,0 +1,110 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import { compact, shuffle } from 'lodash';
+import { apm, ApmFields, EntityArrayIterable, timerange } from '../..';
+import { generateLongId, generateShortId } from '../../lib/utils/generate_id';
+import { Scenario } from '../scenario';
+
+function generateExternalSpanLinks() {
+  // randomly creates external span links 0 - 10
+  return Array(Math.floor(Math.random() * 11))
+    .fill(0)
+    .map(() => ({ span: { id: generateLongId() }, trace: { id: generateShortId() } }));
+}
+
+function getSpanLinksFromEvents(events: ApmFields[]) {
+  return compact(
+    events.map((event) => {
+      const spanId = event['span.id'];
+      return spanId ? { span: { id: spanId }, trace: { id: event['trace.id']! } } : undefined;
+    })
+  );
+}
+
+const scenario: Scenario<ApmFields> = async () => {
+  return {
+    generate: ({ from, to }) => {
+      const instanceGo = apm.service('Service A', 'production', 'go').instance('instance-a');
+      const serviceAEvents = timerange(
+        new Date('2022-04-25T19:00:00.000Z'),
+        new Date('2022-04-25T19:01:00.000Z')
+      )
+        .interval('1m')
+        .rate(1)
+        .generator((timestamp) => {
+          return instanceGo
+            .transaction('Transaction A')
+            .timestamp(timestamp)
+            .duration(1000)
+            .success()
+            .children(
+              instanceGo
+                .span('GET /service_A', 'custom')
+                .timestamp(timestamp + 50)
+                .duration(100)
+                .success()
+            );
+        });
+
+      const serviceAAsArray = serviceAEvents.toArray();
+      const serviceALinks = getSpanLinksFromEvents(serviceAAsArray);
+
+      const instanceJava = apm.service('Service B', 'production', 'java').instance('instance-b');
+      const serviceBevents = timerange(from, to)
+        .interval('1m')
+        .rate(1)
+        .generator((timestamp) => {
+          return instanceJava
+            .transaction('Transaction B')
+            .timestamp(timestamp)
+            .duration(1000)
+            .success()
+            .children(
+              instanceJava
+                .span('GET /service_B', 'external')
+                .defaults({
+                  'span.links': shuffle([...generateExternalSpanLinks(), ...serviceALinks]),
+                })
+                .timestamp(timestamp + 50)
+                .duration(900)
+                .success()
+            );
+        });
+
+      const serviceBAsArray = serviceBevents.toArray();
+      const serviceBLinks = getSpanLinksFromEvents(serviceBAsArray);
+
+      const instanceRuby = apm.service('Service C', 'production', 'ruby').instance('instance-c');
+      const serviceC = timerange(from, to)
+        .interval('1m')
+        .rate(1)
+        .generator((timestamp) => {
+          return instanceRuby
+            .transaction('Transaction C')
+            .timestamp(timestamp)
+            .duration(1000)
+            .success()
+            .children(
+              instanceRuby
+                .span('GET /service_C', 'external')
+                .defaults({ 'span.links': serviceBLinks })
+                .timestamp(timestamp + 50)
+                .duration(900)
+                .success()
+            );
+        });
+
+      return new EntityArrayIterable(serviceAAsArray)
+        .merge(serviceC)
+        .merge(new EntityArrayIterable(serviceBAsArray));
+    },
+  };
+};
+
+export default scenario;

x-pack/plugins/apm/common/elasticsearch_fieldnames.ts

@@ -74,6 +74,10 @@ export const SPAN_DESTINATION_SERVICE_RESPONSE_TIME_COUNT =
 export const SPAN_DESTINATION_SERVICE_RESPONSE_TIME_SUM =
   'span.destination.service.response_time.sum.us';
 
+export const SPAN_LINKS = 'span.links';
+export const SPAN_LINKS_TRACE_ID = 'span.links.trace.id';
+export const SPAN_LINKS_SPAN_ID = 'span.links.span.id';
+
 // Parent ID for a transaction or span
 export const PARENT_ID = 'parent.id';
 

x-pack/plugins/apm/common/span_links.ts

@@ -0,0 +1,24 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { AgentName } from '../typings/es_schemas/ui/fields/agent';
+import { Environment } from './environment_rt';
+
+export interface SpanLinkDetails {
+  traceId: string;
+  spanId: string;
+  details?: {
+    agentName: AgentName;
+    serviceName: string;
+    duration: number;
+    environment: Environment;
+    transactionId?: string;
+    spanName?: string;
+    spanSubtype?: string;
+    spanType?: string;
+  };
+}