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What is the Sidecar?

The Sidecar uses SSE (Server-Sent Events) to forward events to the Spotlight overlay. It is a standalone server that can be deployed on the same machine as the Spotlight overlay or on a different machine.

It receives POST requests on /stream from the Sentry SDKs or any other source and forwards them to the Spotlight overlay via SSE.

By default the Sidecar listens on port 8969 and the Spotlight overlay connects to it on http://localhost:8969/stream.

The url can be configured via the sidecar config variable in the Spotlight overlay see Configuration.

Also in the Sentry SDKs the URL can be configured via the spotlight option, for example in the Python SDK:

import sentry_sdk

Spotlight provides a number of convenience utilities to run the Sidecar, and in some cases it will run automatically with an integration (suchy as in Astro).

NPX Run the Sidecar with Node.
Vite Run the Sidecar as a Vite plugin.
Webpack Run the Sidecar as a Webpack plugin.
Docker Run the Sidecar via a Docker image.