# Preview server (/docs/core/git/preview-server)



# Preview server [#preview-server]

The live preview needs your docs dev server running. Atlas can start and stop that server for you, show its logs, and tell you whether it is up, so you do not have to keep a separate terminal open.

<ThemeImage name="preview-server" alt="The preview server view" />

## Starting and stopping [#starting-and-stopping]

Atlas runs the command set by `previewCommand` in [atlas.json](/docs/core/getting-started/the-workspace), which is `bun run dev` for the Coolify docs. Start it from the preview server view, and stop or restart it whenever you need.

Once it is reachable, the [editor preview](/docs/core/editing/editor) switches to a live iframe of the real rendered pages.

## Live logs [#live-logs]

The view streams the server's output, so when a build error or warning appears, you see it right away instead of digging through a terminal.

## Status [#status]

Atlas tracks the server's state and labels it clearly:

* **Online** means Atlas started the server and it is responding.
* **Online (external)** means the server is responding, but something other than Atlas started it, like a terminal you already had open.
* **Starting** means it is booting up.
* **Offline** means nothing is responding yet.

<Callout type="info">
  The "online (external)" state is handy: if you already run `bun run dev` in a terminal, Atlas notices and uses it for the live preview instead of starting a second one.
</Callout>

## Configuration [#configuration]

The **Configuration** tab, next to the server view, controls how Atlas runs your dev server. Every setting here is also a field in [atlas.json](/docs/core/getting-started/the-workspace), so you can edit it on the page or in the file directly.

<ThemeImage name="preview-server-configuration" alt="The preview server configuration tab" />

* **Command** (`previewCommand`): the command Atlas runs to start the server, like `bun run dev`.
* **URL** (`previewUrl`): the address Atlas opens for the live preview and checks for reachability.
* **Health check path** (`previewHealthPath`): an optional path, like `/health`, that Atlas requests to decide whether the server is really up. Leave it blank to just check the URL.
* **Auto-start** (`previewAutoStart`): start the preview server automatically when Atlas launches, so the live preview is ready without a click.
* **Auto-restart** (`previewAutoRestart`): bring the server back up automatically if it crashes.
* **Environment variables** (`previewEnv`): extra variables passed to the preview command, for any config your dev server needs.

<Callout type="info">
  Turn on **auto-start** if you always want the live preview ready, and **auto-restart** if your dev server is prone to falling over. With both on, Atlas keeps the preview running without you thinking about it.
</Callout>

## Next steps [#next-steps]

<Cards>
  <Card title="Track issues" href="/docs/core/github/issues" />

  <Card title="Set up your workspace" href="/docs/core/getting-started/the-workspace" />
</Cards>