Integrate flags with Runtime Logs

On your dashboard, the Logs tab displays your runtime logs. It can also display any feature flags your application evaluated while handling requests.

To make the runtime logs aware of your feature flag call reportValue(name, value) with the flag name and value to be reported. Each call to reportValue will show up as a distinct entry, even when the same key is used:

import { reportValue } from '@vercel/flags';
 
// force dynamic mode so the flag actually gets reported,
// otherwise the route would be static
export const dynamic = 'force-dynamic';
 
export async function GET() {
  reportValue('summer-sale', false);
  return Response.json({ ok: true });
}

The following limits apply to reported values:

• Keys are truncated to 256 characters
• Values are truncated to 256 characters
• Reported values must be JSON serializable or they will be ignored