[RUM-13448] Add source code context injection for microfrontend #255

amortemousque · 2025-12-18T08:53:10Z

What and why?

This PR adds source code context injection capabilities to the RUM plugin, enabling customers to identify which microfrontend originates each RUM event in their applications. It focuses on setups with separated bundles loaded via dynamic imports (e.g., module federation) by injecting source code metadata at entry points.

How?

New sourceCodeContext option in RUM plugin config that accepts service and version
Injects minified, SSR-safe snippet that creates DD_SOURCE_CODE_CONTEXT global variable mapping stack traces to service/version metadata
E2E tests validating the RUM event enrichment

yoannmoinet

Looks super good.
Thanks for tackling this.

Do you think you could also update ownership of the plugin?

build-plugins/.github/CODEOWNERS

Line 26 in ae68609

    
           packages/plugins/rum                                                  @yoannmoinet

I mostly had small comments.

packages/plugins/rum/src/sourceCodeContext.ts

packages/plugins/rum/src/validate.ts

packages/tests/src/e2e/sourceCodeContext/sourceCodeContext.spec.ts

BeltranBulbarellaDD · 2026-01-15T16:47:09Z

Looks good!

yoannmoinet

Added some comments.
Nothing too bad.

yoannmoinet · 2026-01-30T16:30:15Z

packages/tests/src/e2e/sourceCodeContext/project/index.html

+        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+        <link rel="icon" type="image/svg+xml" sizes="21x21" href="data:image/svg+xml," />
+        <title>Source Code Context Test</title>
+        <script src="https://www.datadoghq-browser-agent.com/us1/v6/datadog-rum.js" type="text/javascript"></script>


Is this the Browser SDK?
Not a fan of having a live resource in the tests.
Would the auto injection work instead?

See my other comment about the plugin's setup.

Yes, I see. I realize I need to make the architecture clearer 🙂
Here’s my reasoning, happy to challenge it.

I want the tests for this plugin to stay isolated and not depend on another plugin. That’s why I didn’t rely on the SDK injection plugin and instead CDN SDK directly. If you prefer I can use the npm SDK setup?

For the e2e assertions, I used beforeSend to capture RUM events instead of intercepting network requests like in other tests. My concern is that compression will soon become mandatory for RUM, beforeSend avoids that complexity

I see, the isolation part makes total sense.

Could we maybe use nock to intercept this request, and direct it to the locally installed SDK? The project already has a dependency on it.

It's really only about the network call.

I understand. I updated the code to use the browser SDK from NPM.
I also removed some tests, following the discussion with Bastien: #255 (comment)

packages/tests/src/e2e/sourceCodeContext/sourceCodeContext.spec.ts

yoannmoinet · 2026-01-30T20:01:02Z

packages/tests/src/e2e/sourceCodeContext/sourceCodeContext.spec.ts

+                (globalThis as any).DD_RUM.init({
+                    clientToken: '<CLIENT_TOKEN>',
+                    applicationId: '<APP_ID>',
+                    enableExperimentalFeatures: ['source_code_context'],
+                    beforeSend: (event: any) => {
+                        (globalThis as any).rum_events.push(event);
+                        return true;
+                    },
+                });


If you do the SDK injection, I guess this will need to be updated as well, since you will most likely pass these options to the plugin configuration (except the beforeSend one).

Can this one be added post initialisation?

For now, you can pass beforeSend only in the init API. If the injection does not support it, I can’t use it.

If needed, you could probably check the events by using the extension callback __ddBrowserSdkExtensionCallback

I’d rather avoid a dependency on the internal __ddBrowserSdkExtensionCallback API. It’s more likely to break, even in minor releases. Maybe, it's just me being overcautious 😄

No such things as internal when exposed globally...

BeltranBulbarellaDD

LGTM

bcaudan · 2026-02-02T14:04:44Z

packages/plugins/rum/src/types.ts


+export type SourceCodeContextOptions = {
+    service: string;
+    version?: string;


❓ question: ‏is there a use case that we want to explicitly support with omitting version?

What if you want to enrich the event with the owner (service) but don’t care about the version or unminification?
Do you think we should enforce the version to prepare customers for the unminification use case?

bcaudan · 2026-02-02T14:16:49Z

packages/tests/src/e2e/sourceCodeContext/sourceCodeContext.spec.ts

+                (globalThis as any).DD_RUM.init({
+                    clientToken: '<CLIENT_TOKEN>',
+                    applicationId: '<APP_ID>',
+                    enableExperimentalFeatures: ['source_code_context'],
+                    beforeSend: (event: any) => {
+                        (globalThis as any).rum_events.push(event);
+                        return true;
+                    },
+                });


If needed, you could probably check the events by using the extension callback __ddBrowserSdkExtensionCallback

bcaudan · 2026-02-02T14:22:15Z

packages/tests/src/e2e/sourceCodeContext/sourceCodeContext.spec.ts

+            expect(chunkAction).toMatchObject({ version: SERVICE_VERSION, service: SERVICE_NAME });
+        });
+
+        test('Should enrich RUM fetch resources with source code context (service/version)', async ({


💭 thought: ‏It is great to have integrations tests, not sure if we need to have the whole combinatory of cases though, especially in this repo.
If we add more events with source code context, I'd rather only have to update the browser-sdk repository.

As discussed, I’ll keep only one test on event enrichment and move all combinations to the browser-sdk repo for easier maintenance.

yoannmoinet · 2026-02-02T20:46:17Z

packages/tests/package.json

        "typecheck": "tsc --noEmit"
    },
    "dependencies": {
+        "@datadog/browser-rum": "6.26.0",


Can you use the same version already imported in the repo, or update all the other versions to fit that one.

amortemousque force-pushed the aymeric/rum-microfrontend branch 2 times, most recently from f38fce4 to 761d68d Compare December 18, 2025 09:28

yoannmoinet reviewed Dec 18, 2025

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amortemousque mentioned this pull request Jan 13, 2026

⚗️[MFE] Source code context event enrichment DataDog/browser-sdk#3926

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amortemousque force-pushed the aymeric/rum-microfrontend branch from 761d68d to da7caff Compare January 28, 2026 14:43

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amortemousque closed this Jan 29, 2026

amortemousque force-pushed the aymeric/rum-microfrontend branch from da7caff to 405d4b4 Compare January 29, 2026 14:54

amortemousque reopened this Jan 29, 2026

amortemousque marked this pull request as ready for review January 29, 2026 14:55

Add source code context injection

536f84d

amortemousque force-pushed the aymeric/rum-microfrontend branch from 70018c9 to 536f84d Compare January 29, 2026 15:38

Make @DataDog/rum-browser of packages/plugins/rum

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yoannmoinet reviewed Jan 30, 2026

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Remove debug logs

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BeltranBulbarellaDD approved these changes Feb 2, 2026

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bcaudan reviewed Feb 2, 2026

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Simplify test + use npm browser SDK version

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yoannmoinet reviewed Feb 2, 2026

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[RUM-13448] Add source code context injection for microfrontend #255

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[RUM-13448] Add source code context injection for microfrontend #255

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amortemousque commented Dec 18, 2025 •

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