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Reference: Fastify adapter | Server

docs/src/content/en/reference/server/fastify-adapter.mdx

2025-12-183.6 KB
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import Steps from "@site/src/components/Steps"; import StepItem from "@site/src/components/StepItem"; import PropertiesTable from "@site/src/components/PropertiesTable";

Fastify adapter

The @mastra/fastify package provides a server adapter for running Mastra with Fastify.

:::info

For general adapter concepts (constructor options, initialization flow, etc.), see Server Adapters.

:::

Installation

Install the Fastify adapter and Fastify framework:

bash
npm install @mastra/fastify@latest fastify

Usage example

typescript
import Fastify from 'fastify'
import { MastraServer } from '@mastra/fastify'
import { mastra } from './mastra'

const app = Fastify({ logger: true })
const server = new MastraServer({ app, mastra })

await server.init()

app.listen({ port: 3000 }, (err, address) => {
  if (err) {
    console.error(err)
    process.exit(1)
  }
  console.log(`Server running on ${address}`)
})

Constructor parameters

<PropertiesTable content={[ { name: 'app', type: 'FastifyInstance', description: 'Fastify app instance', isOptional: false, }, { name: 'mastra', type: 'Mastra', description: 'Mastra instance', isOptional: false, }, { name: 'prefix', type: 'string', description: 'Route path prefix (e.g., /api/v2)', isOptional: true, defaultValue: "''", }, { name: 'openapiPath', type: 'string', description: 'Path to serve OpenAPI spec (e.g., /openapi.json)', isOptional: true, defaultValue: "''", }, { name: 'bodyLimitOptions', type: 'BodyLimitOptions', typeDescription: '{ maxSize: number, onError: (error: unknown) => unknown }', description: 'Request body size limits', isOptional: true, }, { name: 'streamOptions', type: 'StreamOptions', typeDescription: '{ redact?: boolean }', description: 'Stream redaction config. When true (default), redacts sensitive data (system prompts, tool definitions, API keys) from stream chunks before sending to clients.', isOptional: true, defaultValue: '{ redact: true }', }, { name: 'customRouteAuthConfig', type: 'Map<string, boolean>', description: 'Per-route auth overrides. Keys are METHOD:PATH (e.g., GET:/api/health). Value false makes route public, true requires auth.', isOptional: true, }, { name: 'tools', type: 'ToolsInput', typeDescription: 'Record<string, ToolAction | VercelTool>', description: 'Available tools for the server', isOptional: true, }, { name: 'taskStore', type: 'InMemoryTaskStore', description: 'Task store for A2A (Agent-to-Agent) operations', isOptional: true, }, { name: 'mcpOptions', type: 'MCPOptions', typeDescription: '{ serverless?: boolean, sessionIdGenerator?: () => string }', description: 'MCP transport options. Set serverless: true for stateless environments like Cloudflare Workers or Vercel Edge.', isOptional: true, }, ]} />

Manual initialization

For custom middleware ordering, call each method separately instead of init(). See manual initialization for details.

Examples