Sessions - Provide more options to control session creation

[Angelodaniel]

Problem Statement

Observation - Session instrumentation handler does start sessions for each new URL state
Problem - webviews use URL to pass information between native app and webview, this triggers a lot of “fake” sessions and consumes unnecessary data.

Link to source:

sentry-javascript/packages/browser/src/integrations/browsersession.ts

Lines 30 to 35 in ba390df

	addHistoryInstrumentationHandler(({ from, to }) => {
	// Don't create an additional session for the initial route or if the location did not change
	if (from !== undefined && from !== to) {
	startSession({ ignoreDuration: true });
	captureSession();
	}

Solution Brainstorm

This integration should support configuration options similar to how breadcrumbsIntegration works. The integration could accept options like:

interface BrowserSessionOptions { 
  // Disable automatic session creation on URL changes
  trackUrlChanges?: boolean;    
  // Or provide a callback to determine if session should be created 
  shouldCreateSession?: (from: string, to: string) => boolean;
}

Additional Context

Currently it's only possible to disable session tracking completely.

Priority

_{React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.}

[linear]

JS-1526

[JPeer264]

@Angelodaniel I was just talking with @Lms24 about this and thought about having an option called mode which changes the way how we start sessions. This option could look like this:

  /**
   * Controls how sessions are created.
   *
   * - `'single'`: Creates a single session per page load. URL changes are ignored.
   *   Use this for webviews or when you want one session per "visit".
   *
   * - `'navigation'`: Creates a new session on each URL change (default).
   *   Use this for SPAs where each navigation should be tracked as a separate session.
   *
   * @default 'navigation'
   */
  mode?: SessionMode;

This means that mode: 'single' should then be the option to solve this issue. Would that make sense for this use case?

[Angelodaniel]

I've asked @arturluik to chime in! he'll check internally and respond 👍

[arturluik]

The proposed solution partially covers it 🤔

Let's imagine a scenario where SPA applications that work with React Router still want to measure sessions for each route change. Maybe adding sessionMode: 'single' and exposing startSession() to enable custom session start implementations would be more scalable?

For examples something together with useLocation() could work

function SomeComponent() {
  let location = useLocation()

  React.useEffect(() => {
      startSession({ ignoreDuration: true }); 
      captureSession(); 
  }, [location]);

  return (
    // ...
  );
}

EDIT: Mybad, @sentry/core already exposes startSession(), sessionMode: 'single' could theoretically work :) Leaving it up to the maintainers to judge whether this reasoning behind that flag is easy enough for customer to understand

An alternative could be to make the session start as part of the Sentry's React Router integration, so consumers don't need to think about it and rely on statndard implementation :) (Start sessio only when route actually changes)