feat: support yml anchors during push command

__tests__/push/monitor.test.ts

@@ -347,6 +347,63 @@ heartbeat.monitors:
         },
       });
     });
+
+    it('support anchors', async () => {
+      await writeHBFile(`
+http-type: &http-type
+  type: http
+schedule5: &schedule-5
+  schedule: '@every 5m'
+team-tag: &team-tag
+  tags:
+    - team1
+    - team2
+
+heartbeat.monitors:
+- id: http1
+  name: "http1"
+  schedule: '@every 1m'
+  <<: *http-type
+  <<: *team-tag
+  urls: "https://blog.elastic.co"
+- id: http2
+  name: "http2"
+  <<: *http-type
+  <<: *schedule-5
+  urls: "https://elastic.co"
+- id: tcp1
+  name: "tcp1"
+  type: tcp
+  <<: *schedule-5
+  hosts: ["elastic.co:443"]
+      `);
+      const [mon1, mon2, mon3] = await createLightweightMonitors(
+        PROJECT_DIR,
+        opts
+      );
+      expect(mon1.config).toMatchObject({
+        id: 'http1',
+        name: 'http1',
+        schedule: 1,
+        type: 'http',
+        tags: ['team1', 'team2'],
+        urls: 'https://blog.elastic.co',
+      });
+      expect(mon2.config).toMatchObject({
+        id: 'http2',
+        name: 'http2',
+        schedule: 5,
+        type: 'http',
+        urls: 'https://elastic.co',
+      });
+      expect(mon3.config).toMatchObject({
+        id: 'tcp1',
+        name: 'tcp1',
+        schedule: 5,
+        type: 'tcp',
+        hosts: ['elastic.co:443'],
+      });
+    });
   });
 
   describe('parseAlertConfig', () => {

src/push/monitor.ts

@@ -25,7 +25,7 @@
 
 import { mkdir, rm, readFile } from 'fs/promises';
 import { extname, join } from 'path';
-import { LineCounter, parseDocument, YAMLSeq, YAMLMap } from 'yaml';
+import { LineCounter, parseDocument, Document, YAMLSeq, YAMLMap } from 'yaml';
 import { bold, red } from 'kleur/colors';
 import { Bundler } from './bundler';
 import { SYNTHETICS_PATH, totalist, indent, warn } from '../helpers';
@@ -188,8 +188,9 @@ export async function createLightweightMonitors(
     const lineCounter = new LineCounter();
     const parsedDoc = parseDocument(content, {
       lineCounter,
+      merge: true,
       keepSourceTokens: true,
-    });
+    }) as Document.Parsed;
     // Skip other yml files that are not relevant
     const monitorSeq = parsedDoc.get('heartbeat.monitors') as YAMLSeq<YAMLMap>;
     if (!monitorSeq) {
@@ -203,21 +204,29 @@ export async function createLightweightMonitors(
       warnOnce = true;
     }
 
+    // Store the offsets of each monitor in the sequence to construct the source
+    // location later for capturing the error
+    const offsets = [];
     for (const monNode of monitorSeq.items) {
+      offsets.push(monNode.srcToken.offset);
+    }
+
+    const mergedConfig = parsedDoc.toJS()['heartbeat.monitors'];
+    for (let i = 0; i < mergedConfig.length; i++) {
+      const monitor = mergedConfig[i];
       // Skip browser monitors from the YML files
-      if (monNode.get('type') === 'browser') {
+      if (monitor['type'] === 'browser') {
         continue;
       }
-      const config = monNode.toJSON();
-      const { line, col } = lineCounter.linePos(monNode.srcToken.offset);
+      const { line, col } = lineCounter.linePos(offsets[i]);
       try {
-        const mon = buildMonitorFromYaml(config, options);
+        const mon = buildMonitorFromYaml(monitor, options);
         mon.setSource({ file, line, column: col });
         monitors.push(mon);
       } catch (e) {
         let outer = bold(`Aborted: ${e}\n`);
         outer += indent(
-          `* ${config.id || config.name} - ${file}:${line}:${col}\n`
+          `* ${monitor.id || monitor.name} - ${file}:${line}:${col}\n`
         );
         throw red(outer);
       }