web: add `WindowLoad` OpenTelemetry auto instrumentation

Created by: valerybugakov

Context

Adds auto instrumentation of the window load event based on Web Performance API navigation entries.

1. Listens to the first Web Performance navigation entries update.
2. Creates the WINDOW_LOAD span capturing timings from FETCH_START till LOAD_EVENT_END.
3. Adds performance navigation events to the WINDOW_LOAD span.
4. Adds performance paint events to the WINDOW_LOAD span.
5. Creates nested spans for all resources loaded before the LOAD_EVENT_END.

Implementation

The implementation is based on the OpenTelemetry Instrumentation Document Load. The implementation is forked because of various issues blocking the integration with other auto instrumentations.

• RUM integration
• Fetch integration

The implementation is experimental. The plan is to pilot this span structure along with code helpers created for this instrumentation to see if we want to change them based on use-cases we encounter instrumenting other parts of the application like the Blob view.

Traces

ConsoleBatchSpanExporter

Honeycomb

Trace example

Resources

• The Navigation Timing API documentation
• The Navigation Timing spec processing model
• Resource Timing spec processing model

Test plan

1. ENABLE_OPEN_TELEMETRY=true sg start web-standalone.
2. Open web application.
3. See the windowLoad span in the console.

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.