> ## Documentation Index
> Fetch the complete documentation index at: https://unkey.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Environments

> Configure isolated deployment environments in Unkey to separate production traffic from preview and staging builds with scoped settings.

<Info>
  Unkey Deploy is in public beta. To try it, open the product switcher in the
  top-left of the dashboard and select **Deploy**. During beta, deployed
  resources are free. We're eager for feedback, so let us know what you think
  on [Discord](https://unkey.com/discord), [X](https://x.com/unkeydev), or
  email [support@unkey.com](mailto:support@unkey.com).
</Info>

An environment is an isolated deployment target within an [app](/platform/apps/overview). Each environment has its own deployments, [variables](/platform/variables/overview), [custom domains](/networking/domains), and [Sentinel policies](/platform/sentinel/overview).

## Production and preview

Every app gets two environments:

| Environment    | Purpose                                                                  |
| -------------- | ------------------------------------------------------------------------ |
| **Production** | Serves live traffic. Runs three Sentinel replicas for high availability. |
| **Preview**    | For testing branches before merging. Runs one Sentinel replica.          |

Unkey creates both environments automatically when you create a project. You don't need to set them up manually.

<Note>
  Custom environments beyond production and preview are not yet available.
</Note>

## Branch mapping

When you connect a [GitHub repository](/build-and-deploy/github), Unkey maps branches to environments:

* Pushes to the default branch (typically `main`) deploy to **production**.
* Pushes to any other branch deploy to **preview**.

Each push creates a new [deployment](/build-and-deploy/deployments) in the corresponding environment.

## Environment-scoped configuration

Configuration is scoped per environment, so production and preview can differ:

* **Variables**: Different database URLs, API keys, and feature flags for each environment
* **Custom domains**: Production might use `api.acme.com` while preview uses auto-generated domains
* **Regions and instances**: Run production in multiple regions with higher instance counts, and preview in a single region
* **Sentinel policies**: Apply stricter rate limits or authentication rules in production

## Sticky domains

Each environment has a sticky domain that always points to the latest deployment in that environment:

```text theme={"theme":"kanagawa-wave"}
<project>-<app>-<environment>-<workspace>.unkey.app
```

When a new deployment reaches the Ready state, the environment domain updates automatically. You don't need to reconfigure DNS or update your clients.

Production environments also get a live domain without the environment name:

```text theme={"theme":"kanagawa-wave"}
<project>-<app>-<workspace>.unkey.app
```

See [Wildcard domains](/networking/wildcard-domains) for the full domain naming pattern.

## Deployments per environment

An environment can have many deployments, but only one is active at a time.

In production, when a new deployment goes live, the previous one transitions to standby after 30 minutes. Standby deployments are available for [rollbacks](/build-and-deploy/rollbacks).

In preview environments, deployments stay running as long as they receive traffic. Idle preview deployments (zero requests for six hours) are automatically archived to free up resources.

## Next steps

<CardGroup cols={2}>
  <Card title="Variables" icon="key" href="/platform/variables/overview">
    Configure environment-specific variables
  </Card>

  <Card title="Custom domains" icon="globe" href="/networking/domains">
    Serve your app from your own domain
  </Card>
</CardGroup>