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> Discover all available pages from the documentation index: https://mastra.ai/llms.txt

# Mastra server

Mastra compiles your application into a standalone Node.js server that can run on any platform supporting Node.js, Bun, or Deno.

> **Tip:** This guide covers deploying the standalone server generated by `mastra build`. If you need to integrate Mastra into an existing Express or Hono application, see [Server Adapters](https://mastra.ai/docs/server/server-adapters) instead.

## Building your application

Run the build command from your project root:

```bash
mastra build
```

This creates a `.mastra` directory containing your production-ready server. Read the [`mastra build`](https://mastra.ai/reference/cli/mastra) reference for all available flags.

## Build output

After building, Mastra creates the following structure:

```text
.mastra/
├── .build/                # Intermediate build artifacts (module maps, analysis)
└── output/
    ├── index.mjs          # Server entry point
    ├── mastra.mjs         # Your bundled Mastra configuration
    ├── tools.mjs          # Aggregated tool exports
    ├── tools/             # Individual tool bundles
    ├── package.json       # Production dependencies
    ├── node_modules/      # Installed dependencies
    ├── .npmrc             # Copied from your project (if present)
    ├── public/            # Static assets (if src/mastra/public exists)
    └── playground/        # Studio UI (if --studio flag used)
```

The `output` directory is self-contained. You can copy it to any server and run it directly.

## Running the server

Start the server using the Mastra CLI:

```bash
mastra start
```

Or run directly with Node.js:

```bash
node .mastra/output/index.mjs
```

The `mastra start` command provides additional features:

- Loads environment variables from `.env.production` and `.env`
- Provides helpful error messages for missing modules
- Handles process signals for graceful shutdown

Read the [`mastra start`](https://mastra.ai/reference/cli/mastra) reference for all available flags.

## Build configuration

### Build-time configuration

Mastra reads the `bundler`, `deployer`, and `server` options while it builds your application. Keep those options as direct properties of the object passed to `new Mastra()` so the build can extract them.

The following entry-file shape works:

```typescript
import { Mastra } from '@mastra/core/mastra'

export const mastra = new Mastra({
  bundler: {
    externals: ['sharp'],
  },
  server: {
    port: 4111,
  },
})
```

The value of each option can come from a variable, import, or function call. The option itself must remain a direct property. Don't hide build-time options behind a factory call or an object spread:

```typescript
const options = {
  bundler: {
    externals: ['sharp'],
  },
}

// These patterns prevent Mastra from extracting `bundler` during the build.
export const mastra = new Mastra(createMastraOptions())
export const otherMastra = new Mastra({ ...options })
```

When Mastra can't extract an option, it uses the default build behavior for that option. See the [configuration reference](https://mastra.ai/reference/configuration) for the available `bundler`, `deployer`, and `server` settings.

### Public folder

If a `public` folder exists in your Mastra directory (`src/mastra/public`), its contents are copied to the output directory during build. These files are served as static assets by the server.

### Mastra configuration

The build process respects configuration in your Mastra instance. For server behavior like CORS, timeouts, and middleware, see [server overview](https://mastra.ai/docs/server/overview). For all available options, see the [configuration reference](https://mastra.ai/reference/configuration).

## Build process

The build follows these steps:

1. **Locates entry file**: Finds `index.ts` or `index.js` in your Mastra directory.
2. **Discovers tools**: Scans for tool files matching `{mastraDir}/tools/**/*.{js,ts}`, excluding test files.
3. **Analyzes dependencies**: Determines which packages to bundle vs. install externally.
4. **Bundles code**: Uses Rollup with tree-shaking and optional source maps.
5. **Generates server**: Creates a Hono-based HTTP server as `index.mjs`.
6. **Installs dependencies**: Runs `npm install` in the output directory.
7. **Copies assets**: Copies `public` folder and `.npmrc` if present.

## Environment variables

| Variable             | Description                                                                 |
| -------------------- | --------------------------------------------------------------------------- |
| `PORT`               | Server port (default: `4111`)                                               |
| `MASTRA_STUDIO_PATH` | Path to Studio build directory (default: `./playground`)                    |
| `MASTRA_SKIP_DOTENV` | Skip loading `.env` files when set                                          |
| `NODE_OPTIONS`       | Node.js options (e.g., `--max-old-space-size=4096` for build memory issues) |

## Server endpoints

The built server exposes endpoints for health checks, agents, workflows, and more:

| Endpoint                | Description                                                            |
| ----------------------- | ---------------------------------------------------------------------- |
| `GET /health`           | Health check endpoint, returns `200 OK`                                |
| `GET /api/openapi.json` | OpenAPI specification (if `server.build.openAPIDocs` is enabled).      |
| `GET /swagger-ui`       | Interactive API documentation (if `server.build.swaggerUI` is enabled) |

This list isn't exhaustive. To view all endpoints, run `mastra dev` and visit `http://localhost:4111/swagger-ui`.

To add your own endpoints, see [Custom API Routes](https://mastra.ai/docs/server/custom-api-routes).

## Graceful shutdown and rolling deploys

By default, the generated server handles `SIGINT` and `SIGTERM`. It stops accepting connections, waits up to [`server.drainTimeout`](https://mastra.ai/reference/configuration) for active requests and streams, then runs `mastra.shutdown()`. Shutdown gives in-flight workflow runs (including durable agent runs) the same drain window to finish before workers and pub/sub subscriptions are torn down. The drain timeout defaults to 5 seconds. A second signal terminates the process immediately. See [`server.handleShutdownSignals`](https://mastra.ai/reference/configuration) if you need to manage signals yourself.

Increase `drainTimeout` when your hosting platform's termination grace period can accommodate longer turns. The HTTP drain and the workflow drain run one after the other, so keep enough time for both plus shutdown cleanup.

If you call `mastra.shutdown()` yourself, pass `drainTimeout` to control how long it waits for in-flight workflow runs:

```typescript
await mastra.shutdown({ drainTimeout: 30_000 })
```

```typescript
import { Mastra } from '@mastra/core/mastra'

export const mastra = new Mastra({
  server: {
    drainTimeout: 240_000,
  },
})
```

A plain `agent.stream()` call can't resume after its server process exits. If a stream ends without its expected terminal event, treat the turn as interrupted and let the client retry or reconcile it. Use [durable agents](https://mastra.ai/docs/harness/durable-agents) when turns must survive process replacement. [Crash recovery](https://mastra.ai/docs/harness/durable-agents) requires shared persistent run storage and idempotent tools. Replaying missed events after a restart also requires a shared persistent cache such as Redis because the default event cache is in-memory. Multi-replica recovery doesn't yet use a distributed lease.

## Troubleshooting

### Memory errors during build

If you encounter `JavaScript heap out of memory` errors:

```bash
NODE_OPTIONS="--max-old-space-size=4096" mastra build
```

## Related

- [Server Overview](https://mastra.ai/docs/server/overview): Configure server behavior, middleware, and authentication
- [Server Adapters](https://mastra.ai/docs/server/server-adapters): Use Express or Hono instead of `mastra build`
- [Custom API Routes](https://mastra.ai/docs/server/custom-api-routes): Add custom HTTP endpoints
- [Durable Agents](https://mastra.ai/docs/harness/durable-agents): Persist agent runs so they survive process restarts
- [Configuration Reference](https://mastra.ai/reference/configuration): Full configuration options