Vercel

This topic explains how to send logs from Vercel to LaunchDarkly observability features. If you deploy your applications on Vercel, you can configure a log drain to automatically forward your server-side logs to LaunchDarkly. This includes build logs, serverless function logs, edge function logs, and static access logs. Once configured, these logs appear in the Logs page of the LaunchDarkly user interface.

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Prerequisites

Before you configure the Vercel log drain, you must:

• Have a Vercel account with at least one project
• Have LaunchDarkly observability enabled for your project
• Know your LaunchDarkly client-side ID

To find your client-side ID:

1. In the LaunchDarkly UI, click the project dropdown to open the project menu.
2. Select Project settings.
3. Click Environments.
4. Find the environment you want to use and copy the Client-side ID value.

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Configure the Vercel log drain

You can configure the log drain directly in the Vercel dashboard. To configure the Vercel log drain:

1. In Vercel, navigate to your team or account Settings.
2. Click Log Drains in the sidebar.
3. Click Add Log Drain.
4. Select the Projects and Environments you want to collect logs from.
5. Select Sources to specify which types of logs to send. You can choose from:
   • Build logs
   • Edge function logs
   • Lambda (serverless function) logs
   • Static access logs
6. Select NDJSON for Delivery format.

8. Click Add Custom Headers.
9. Add a header with the name x-highlight-project and set the value to your LaunchDarkly client-side ID.
10. Click Verify to test the connection.
11. Click Create Log Drain to save the configuration.

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Verify that logs are being received

After you configure the log drain, Vercel begins forwarding logs to LaunchDarkly. To verify that your logs are being received:

1. Open the Telemetry section and navigate to the Logs list.
2. Search for logs with source:vercel or from your Vercel-deployed services.

It may take a few minutes for logs to appear after you first configure the log drain.

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Search attributes

Logs from Vercel include the following attributes that you can use when searching:

Attribute	Description
vercel.source	The source of the log, such as lambda, edge, build, or static.
vercel.projectId	The Vercel project ID.
vercel.deploymentId	The Vercel deployment ID.
vercel.host	The hostname that served the request.
vercel.path	The request path.
vercel.statusCode	The HTTP status code of the response.

To learn more about searching for logs, read Search specification.

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Filtering logs

You can configure ingestion filters to control which logs from Vercel are stored in LaunchDarkly. This is useful for excluding noisy logs or limiting ingestion to stay within your observability quotas. To learn more, read Filters.